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Access Broadband over Power Line Systems

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Released: October 24, 2011

Federal Communications Commission

FCC 11-160

Before the

Federal Communications Commission

Washington, D.C. 20554

In the Matter of
)
)

Amendment of Part 15 regarding new requirements )
ET Docket No. 04-37
and measurement guidelines for Access Broadband )
over Power Line Systems
)
)

Carrier Current Systems, including Broadband over )
ET Docket No. 03-104
Power Line Systems
)
)

SECOND REPORT AND ORDER

Adopted: October 20, 2011

Released: October 24, 2011

By the Commission:

TABLE OF CONTENTS

Heading
Paragraph #
I.
INTRODUCTION .................................................................................................................................. 1
II. BACKGROUND .................................................................................................................................... 4
III. DISCUSSION....................................................................................................................................... 14
A. The Potential for Harmful Interference ................................................................................... 21
B. Measurement Distance Extrapolation Issues........................................................................... 58
C. The Access BPL Database..................................................................................................... 101
IV. PROCEDURAL MATTERS.............................................................................................................. 102
V. ORDERING CLAUSES..................................................................................................................... 105
APPENDICES
APPENDIX A - Parties Submitting Comments
APPENDIX B Final Regulatory Flexibility Analysis
APPENDIX C Final Rules
APPENDIX D Measurement Guidelines for Broadband Over Power Line (BPL) Devices or Current
Systems (CCS) and Certification Requirements For Access BPL Devices
APPENDIX E Extrapolated Emission Maximum Allowable Levels Using Slant-Range Method with
Various Power Line Heights
APPENDIX F List of Additional Materials Included in the Record

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I.

INTRODUCTION

1. In this Second Report and Order (Second Order), we fundamentally affirm our rules for
Access Broadband over Power Line (Access BPL) systems. We also make certain minor
modifications to improve and clarify the rules. These rules provide an appropriate balance between
the dual objectives of providing for Access BPL technology that has potential applications for
broadband and Smart Grid while protecting incumbent radio services against harmful interference.1
2. The Commission adopted rules for Access BPL systems in 20042 and affirmed those
rules in 2006.3 The BPL rules were challenged by the national association for amateur radio,
formally known as the American Radio Relay League (ARRL) in the United States Court of Appeals
for the District of Columbia in ARRL v. FCC.4 In ARRL v. FCC, the court directed the Commission
to: 1) make part of the rulemaking record unredacted versions of several staff technical studies which
the Commission considered in promulgating the rules, 2) provide a reasonable opportunity for public
comment on those studies, and 3) provide a reasoned explanation of its choice of the extrapolation
factor5 for use in measuring radiated emissions from Access BPL systems. In response, the
Commission issued a Request for Further Comment and Further Notice of Proposed Rulemaking in
this proceeding (RFC/FNPRM).6 In the RFC/FNPRM, the Commission took its first step in
responding to the directives of the court in ARRL v. FCC and also took that opportunity to review the
Access BPL extrapolation factor and propose certain changes to the BPL technical rules that appeared
appropriate in view of new information and further consideration of this matter. In this Second
Order, we complete our action addressing the court's concerns and our proposals in the RFC/FNPRM.
We find that the information submitted in response to the RFC/FNPRM does not warrant any changes
to the emissions standards or the extrapolation factor. We are, however, making several refinements
to our Access BPL rules. In particular, we are: 1) modifying the rules to increase the required notch
filtering capability for systems operating below 30 MHz from 20 dB to 25 dB; 2) establishing a new
alternative procedure for determining site-specific extrapolation factors generally as described in the


1 A "smart grid" electricity network includes an intelligent monitoring system that keeps track of all electricity
flowing in the system from suppliers to consumers providing real-time or near-real-time load information to permit
improved transmission management. It also can utilize two-way digital technology to control appliances at
consumers' homes to reduce peaks and even out demand, to save energy, to reduce cost, and to increase reliability
and transparency.
2 Report and Order in ET Docket Nos. 04-37, 03-104 (Amendment of Part 15 Regarding New Requirements and
Measurement Guidelines for Access Broadband Over Power Line Systems, Carrier Current Systems)
, 19 FCC Rcd
21265 (2004) (BPL Order).
3 Memorandum Opinion and Order in ET Docket Nos. 04-37, 03-104 (Amendment of Part 15 Regarding New
Requirements and Measurement Guidelines for Access Broadband Over Power Line Systems; Carrier Current
Systems, including Broadband over Power Line Systems)
, 21 FCC Rcd 9308 (2006) (BPL Reconsideration Order).
4 American Radio Relay League, Incorporated, v. Federal Communications Commission (ARRL v. FCC) 524 F.3d
227 (D.C. Cir. 2008).
5 Because the field strength of radiated emissions decreases with increasing distance from the emitter due to
propagation loss, an "extrapolation" factor is used to adjust the measurement results to account for the difference in
attenuation, when measurements are made at a distance other than the specified distance in the rules.
6 Request for Further Comment and Further Notice of Proposed Rulemaking in ET Dockets No. 04-37 and 03-104
(Amendment of Part 15 Regarding New Requirements and Measurement Guidelines for Access Broadband Over
Power Line Systems; Carrier Current Systems, including Broadband over Power Line Systems)
, 24 FCC Rcd 9669
(2009) (RFC/FNPRM).
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RFC/FNPRM, and 3) adopting a definition for the "slant-range distance" used in the BPL
measurement guidelines to further clarify its application.7 We find that the benefits of the above
changes to the rules outweigh their regulatory costs, as discussed herein.
3. Throughout this proceeding and in its appeal to the court, the ARRL has argued that more
restrictive technical standards are needed to protect the amateur radio service from interference
caused by leakage of radiofrequency (RF) emissions from Access BPL systems. We initially crafted
rules for BPL systems that were based on our existing emission standards for carrier current
communications systems narrow-band devices that couple RF energy onto power line wiring for
communication purposes with a number of additional requirements to promote avoidance and
resolution of harmful interference to licensed services that might occur in the context of BPL
operations.8 We subsequently affirmed those rules in response to petitions for reconsideration by
various parties, including ARRL.9 In this process, we have specifically rejected as unnecessary
repeated requests by ARRL for tighter emissions controls on Access BPL operations. In response to
the court's direction, we provided opportunity in the RFC/FNPRM for interested parties to address the
BPL technical rules and the information developed by our staff that we considered in establishing
those rules, explained our rationale for the extrapolation factor used in measuring BPL emissions,
expressed our tentative satisfaction with the extrapolation factor adopted, while soliciting comment
on whether another value would be more appropriate, and proposed a procedure for determining
site-specific extrapolation factors. Herein, we complete our response to issues raised under the
court's directive.

II.

BACKGROUND

4. In the BPL Order, the Commission adopted rules to regulate the operation of Access BPL
systems as unlicensed, unintentional radiators.10 These BPL systems, which are a form of carrier
current system,11 deliver high speed Internet and other broadband services over the utilities'
medium-voltage delivery power lines to homes and businesses; electric utility companies also use
Access BPL devices to monitor and manage various elements of their electric power distribution
operations as part of "Smart Grid" applications. In adopting the rules for these devices and systems,
the Commission observed that BPL could provide a means to expedite the availability of broadband
Internet service to consumers and businesses in rural and other underserved areas, introduce
additional competition to existing broadband services, promote continued U.S. leadership in


7 Because Access BPL devices are mounted on overhead power lines and the measurement antenna is at a lower
distance closer to the ground, the actual distance from the power line to the measurement antenna is greater than the
horizontal distance from the pole on which the BPL device is mounted to the measurement antenna. The correct
distance for measurement is therefore the "slant range" diagonal distance measured from the center of the
measurement antenna to the nearest point of the overhead power line carrying the Access BPL signal being
measured.
8 BPL Order, 19 FCC Rcd 21265 (2004).
9 BPL Reconsideration Order, 21 FCC Rcd 9308 (2006).
10 An unintentional radiator is defined in the rules as a device that intentionally generates radio frequency energy for
use within the device, or that sends radio frequency signals by conduction to associated equipment via connecting
wiring, but which is not intended to emit RF energy by radiation or induction. See 47 C.F.R. 15.3(z). The Access
BPL regulations are set forth in Sections 15.601-15.615 of the Commission's rules, 47 C.F.R. 15.601-15.615.
11 Carrier current systems transmit radio frequency energy by conduction over electric power lines, see 47 C.F.R.
15.3(f). These systems have been operating successfully as unlicensed campus radio stations in the AM Broadcast
band for over fifty years in the United States at many universities.
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broadband technology, and bring important benefits to the American public.12 At the same time, it
recognized the need to ensure that BPL operations do not cause harmful interference to licensed radio
services.13 Accordingly, the Commission established technical standards, operating restrictions and
measurement guidelines for Access BPL to minimize instances of interference to licensed services
and to facilitate resolution of such interference where it might occur.14 These provisions for
managing interference include: 1) application of the existing emission limits for carrier current
systems in Section 15.109(e) to Access BPL;15 2) requirements that Access BPL devices employ
adaptive interference mitigation techniques to promote avoidance and resolution of harmful
interference; 3) requirements that Access BPL system operators provide information on the areas
where their systems are installed and other technical parameters in a central data base that is
accessible by the public; and 4) specific measurement guidelines and certification requirements for
both Access BPL and other carrier current systems to ensure accurate and repeatable evaluations of
emissions from Access BPL and all other carrier current systems. The rules also include specific
provisions (not relevant here) for certain critical Federal Government and other services in the form
of coordination requirements, exclusion zones and excluded frequency bands.16 The Commission did
not find that the amateur radio service warrants additional protections particular to that service; rather,
it concluded that the general Part 15 rules and the additional specific provisions being adopted for
Access BPL operations are sufficient to protect amateur operations.
5. Following the issuance of the BPL Order, ARRL filed a Freedom of Information Act
(FOIA) request, seeking disclosure of Commission studies of emissions generated by Access BPL
systems. In response to that request, the Commission released five staff presentations in redacted
form and added them to the record in December 2004. ARRL, among others, sought reconsideration
of the BPL Order on February 7, 2005.17 The Commission on reconsideration amended its rules in
part but generally denied ARRL's petition, making one clarification.18 It reiterated the need to ensure
that BPL operations do not cause harmful interference to licensed radio services and recognized that
the substantial benefits of this technology might not be realized if BPL devices were to cause
interference to licensed services and other important radio operations.19
6. Subsequently, ARRL challenged the Commission's Access BPL decisions in the United
States Court of Appeals for the District of Columbia. In its petition for judicial review, ARRL
challenged the Access BPL rules on four grounds, alleging that: 1) the Commission ignored
long-standing precedent by authorizing the operation of unlicensed devices that could interfere with
licensed services and by no longer requiring that operators cease using the unlicensed devices if they
actually cause interference; 2) the Commission did not adequately consider an alternative proposal for


12 BPL Order at 21266 and 21271.
13 Id. at 21266.
14 See 47 C.F.R. 15.601-15.615.
15 See 47 C.F.R. 15.109(e) and 15.209; these limits are codified for Access BPL systems at Section 15.611(b).
16 See 47 C.F.R. 15.615(e)-(f).
17 See ARRL Petition for Reconsideration (filed Feb. 7, 2005 in ET Docket 04-37). See also, ARRL Petition for
Issuance of Further Notice of Proposed Rule Making and for Amendments of Regulations (filed Oct. 18, 2005) in
ET Docket No. 04-37.
18 On reconsideration, the Commission clarified rule section 47 C.F.R. 15.611(c)(1), as requested by ARRL. BPL
Reconsideration Order
at 9320 and 9338.
19 BPL Order at 21266.
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reducing harmful interference that would have limited Access BPL systems to the frequency band
between 30 MHz and 50 MHz, rather than between 1.7 MHz and 80 MHz; 3) the Commission
violated the Administrative Procedure Act (APA) by failing to disclose in unredacted form certain
technical studies prepared by the Commission's engineers that were relied upon in adopting the
rules;20 and 4) the empirical evidence does not support the Commission's decision to retain the
existing 40 dB per decade (40 dB/decade) extrapolation factor to measure Access BPL radiated
emissions at frequencies below 30 MHz, which contain several bands used by amateur licensees.21
7. The court denied in part and granted in part ARRL's petition and remanded the rules to
the Commission for further action.22 It found unpersuasive ARRL's arguments with respect to the
first two points. However, the court found that the Commission failed to satisfy the notice and
comment requirements of the APA by redacting staff studies which it considered in promulgating the
rules and by failing to make a reasoned explanation for its choice of the extrapolation factor for
measuring Access BPL emissions. The court therefore directed the Commission to make the
unredacted staff studies part of the rulemaking record and provide an opportunity for notice and
comment.23 With respect to the extrapolation factor, the court found that the Commission has not
adequately explained its decision and directed the Commission to "either provide a reasoned
justification for retaining an extrapolation factor of 40 dB/decade for Access BPL systems sufficient
to indicate that it has grappled with the 2005 studies [which ARRL submitted in ex parte comments
supporting its petition for reconsideration from the 2004 Order], or adopt another factor and provide a
reasoned explanation for it."24 The court did not suspend the Commission's Access BPL rules
pending further actions by the Commission and the rules have remained in effect.25
8. As directed by the court, the Commission placed into the record of the above proceeding
unredacted versions of five technical staff presentations26 that it had previously submitted in redacted


20 In pertinent part, the APA requires administrative agencies to publish "notice" of "either the terms or substance of
the proposed rule or a description of the subjects and issues involved," in order to "give interested persons an
opportunity to participate in the rule making through submission of written data, views, or arguments," and then,
"[a]fter consideration of the relevant matter presented, the agency shall incorporate in the rules adopted a concise
general statement of their basis and purpose." 5 U.S.C. 553(b), (c). In order to provide sufficient notice, the
agency must disclose any technical studies and staff reports on which it relies. ARRL v. FCC, 524 F.3d at 236,
citing, e.g., NARUC v. FCC, 737 F.2d 1095, 1121 (D.C.Cir.1984).
21 See ARRL v. FCC, at 233. "Decade," a 10 to 1 range, refers to the ratio of the specified measurement distance to
the actual measurement distance. An extrapolation factor of 20 dB per decade treats field strength emissions as if
they attenuate at a rate inversely proportional to the distance from the emitter (1/R), whereas an extrapolation factor
of 40 dB per decade treats emissions as if they attenuate at a rate inversely proportional to the square of the distance
from the emitter (1/R2). If the extrapolation factor is 20 dB per decade instead of 40 dB per decade, the correction
factor would be significantly smaller, thus resulting in lower permitted values for the transmitted emission levels at
the same distance from the emitter. See 47 C.F.R. 15.31(f)(1) and (2).
22 Id., at 231.
23 Id., at 240.
24 Id., at 241.
25 Id.
26 We note that the use of the term "study" or "report" used for these informal presentations of scientifically
collected data, staff notes and observations may imply a greater degree of completion, finality, consideration and
conclusion than is the case here. These presentations of information, impressions, and ideas were just that,
informal presentations by staff engineers to other staff engineers and OET managers. A "study" or "report"
prepared as information or for consideration would normally be in a formal written format for publication and
(continued....)
5

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form.27 The staff presentations included information regarding measured emissions from various
experimental Access BPL systems at locations in Pennsylvania, Maryland, New York, and North
Carolina, that were used to familiarize the Commission and its staff with this new technology.28 These
presentations were considered in the decision-making process along with studies submitted by
commenters such as ARRL and the National Telecommunications and Information Administration
(NTIA). The first two presentations, included in a single file entitled BPL Measurements in Allentown,
PA
, contain data collected on the Amperion BPL system and on the Main.Net BPL system, both in
Allentown, PA.29 The third presentation, Emissions Measurements on CURRENT Technologies Medium
Voltage BPL System
, contains data collected on the CURRENT Technologies (CURRENT) BPL system
in Potomac, MD.30 The fourth presentation, BPL Summary After Briarcliff Manor, NY Test, contains data
collected on the Ambient BPL system in Briarcliff, NY, and some staff observations.31 The fifth
presentation, BPL Emission Test Near Raleigh, NC, contains data collected on the Amperion/Progress
Energy BPL system in Raleigh, NC.32 The Commission observed that the redacted pages mostly contain
information regarding specific test notes and test set-up recommendations with respect to the BPL
systems at the various test sites,33 certain requests from third parties,34 and preliminary and partial data
(Continued from previous page)


reviewed and vetted by agency staff and management, which was not the case in these instances. No formal peer
review was conducted. Thus, while there is much useful scientific information in those presentations that was
considered in our BPL decisions, other content therein is more properly viewed as discussion materials and options
rather than settled conclusions. Accordingly, we will hereinafter refer to these documents as presentations to
differentiate them from the more formal and considered findings of a study or report.
27 See Letter dated April 29, 2009 to ARRL from Julius Knapp, Chief, Office of Engineering and Technology.
28 Two presentations measured emissions from systems marketed by two specific Access BPL manufacturers
(Amperion and Main.Net BPL systems in Allentown, Pennsylvania), and three others measured location-specific
emissions in pilot Access BPL areas in Maryland (CURRENT Technologies BPL system in Potomac), New York
(Ambient BPL system in Briarcliff Manor) and North Carolina (Amperion/Progress Energy BPL system in Raleigh.)
ARRL v. FCC, supra at 237.
29 BPL Measurements in Allentown, PA at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215595,
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215596, and
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215597.
30 Emissions Measurements on CURRENT Technologies Medium Voltage BPL System, at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215597 and
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215598.
31 BPL Summary After Briarcliff Manor, NY Test, at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215598 and
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215599.
32 BPL Emission Test Near Raleigh, NC , at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215599 and
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520215600.
33 BPL Measurements in Allentown, PA, slide 6, labeled "Conclusions Regarding Amperion" and slide 7, labeled
"Recommendations for Amperion"; Emissions Measurements on CURRENT Technologies Medium Voltage BPL
System,
slide 36, labeled "Recommended Future FCC Tests (to understand technology)".
34 BPL Measurements in Allentown, PA, slide 48, labeled "Conclusions Regarding Main.Net" and slide 52, labeled
"Other Issues".
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with respect to the noise floor35 and attenuation rate of the signal strength downline at the test sites36 as
well as the opinions of one staff member as to whether BPL systems are point-source systems37 and that
staff member's opinion on possible ways to treat these systems.38 In the RFC/FNPRM, the Commission
requested comment on the information in those unredacted presentations as it pertains to its BPL
decisions.
9. On July 17, 2009, concurrent with its release of the RFC/FNPRM, the Commission also
placed into the record some additional materials that contain preliminary staff research and
educational information (preliminary research materials) and were not previously available therein
and invited comment on those materials. These materials consist of several working papers and video
files that were used in preparing the staff presentations and for staff education. The Commission
stated that these are materials that it would not routinely, and in this case did not previously, place in
the record. However, the Commission indicated that it now believes it is important to make available
all potentially relevant research and information materials in order to fully and most efficaciously
conclude its examination of the BPL issues. A list of these additional materials is provided in
Appendix F.
10. The Commission also provided an explanation of its reasons for selecting 40 dB/decade as
the measurement distance extrapolation factor for frequencies below 30 MHz. The Commission further
explained why it believes the studies and technical proposal submitted earlier by ARRL do not provide
convincing information that it should use an extrapolation factor that is different from that which it
adopted.39 The Commission also noted the existence of more recent studies that verify the correctness of
its determination, although it did not rely on those studies as ex post facto rationale or justification for its
decision.
11. Consistent with the opportunity provided by the court's remand and its stated intention in the
BPL Order to review the decision on the extrapolation factor if new information becomes available, the
Commission also indicated in the RFC/FNPRM that it would re-examine the current extrapolation factor
in light of the recently issued technical studies addressing the attenuation of BPL emissions with distance
and the efforts by the Institute of Electrical and Electronics Engineers (IEEE) to develop BPL
measurement standards. The Commission stated that as the several studies now available show and as it
has observed previously, there can be considerable variability in the attenuation of emissions from BPL
systems across individual measurement sites that is not captured in the use of a uniform 40 dB/decade


35 BPL Summary After Briarcliff Manor, NY Test, slide 9, labeled "Raleigh Received Levels at 23.2 MHz from One
Overhead Injector" and slide 13, labeled "NTIA Results"; BPL Emission Test Near Raleigh, NC, slide 16, labeled
"Test Description for Mobile Radio Measurements" and slide 23, labeled "Notch Depth".
36 BPL Measurements in Allentown, PA, slide 40, labeled "Summary of Relative Average Levels".
37 BPL Measurements in Allentown, PA, slide 3, labeled "Major Conclusions", slide 17, labeled "Under-Line Field
Strength vs. Distance Down Line" and slide 50, labeled "Conclusions Regarding Access BPL"; BPL Summary After
Briarcliff Manor, NY Test
, slide 17, labeled "New Information Arguing for Caution on HF BPL"; Emissions
Measurements on CURRENT Technologies Medium Voltage BPL System,
slide 35, labeled "Conclusions".
38 BPL Summary After Briarcliff Manor, NY Test, slide 13, labeled "NTIA Results", slide 16, labeled "Skywave
(<30 MHz)", slide 19, labeled "HF Issues and Options", slide 20, labeled "Low VHF Options", and slide 21, labeled
"BPL Spectrum Tradeoffs and Proposals".
39 This explanation of the insufficiencies of the OFCOM studies and of ARRL proposal for a sliding scale
extrapolation factor responded to the Court's directive in ARRL v. FCC that the Commission provide a reasoned
justification for retaining an extrapolation factor of 40 dB/decade for Access BPL systems sufficient to indicate that
it has grappled with the . . . [empirical data] ..."; see RFC/FNPRM at 9679-9680.
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standard. To address this variability, it requested comment on whether it should amend the BPL rules to
1) adjust the extrapolation factor downward to 30 dB or some other fixed value and, 2) as an alternative,
also allow use of a special procedure for determining site-specific BPL extrapolation values using in situ
measurements. The in situ procedure it proposed was based on a concept that was under consideration at
that time by the IEEE working group on power line communications technology electromagnetic
compatibility (EMC) in its draft standard P1775/D2.40
12. In addition, the Commission clarified that parties testing BPL equipment and systems for
compliance with emissions limits in the rules may measure at the standard 30-meter distance rather than
the shorter distances recommended in the BPL measurement guidelines. It requested comments on the
unredacted staff presentations, its selection of an extrapolation factor for BPL systems based on the
slant-range method and the explanation provided therein, and its proposal to allow use of site-specific
extrapolation factors as an alternative to the standard extrapolation factor. The Commission stated that in
the interim, as justified therein, it would continue to apply the extrapolation factor as adopted in the BPL
Order
.
13. Thirty parties submitted comments and nine parties submitted replies in response to the
RFC/FNPRM.41 ARRL submitted a detailed presentation requesting rule changes to further protect the
amateur radio service from harmful interference from Access BPL operations while permitting BPL
systems to operate in the 3 MHz to 80 MHz range without significant constraint. It specifically asks that
we achieve these objectives by requiring that BPL systems employ 1) full-time notching (frequency
avoidance) of all amateur frequency allocations and 2) notch depths of 35 dB below the standard BPL
emissions limit.42 Nine of the commenting parties are parties with interests in the Access BPL industry
who oppose ARRL's requested rule changes or provide other responses to its submissions. The
remaining parties are individual amateur radio licensees who generally support ARRL's position.

III.

DISCUSSION

14. In this proceeding, we have established a regime of rules for Access BPL systems that will
provide a robust environment for the development and deployment of this important new technology
option for delivery of broadband internet/data services while at the same time minimizing the potential for
interference to licensed services caused by leakage from power lines of the RF energy used by BPL
transmissions. As we observed in the BPL Order, there is some potential for increased harmful
interference from BPL operations, particularly in locations within a short distance of the power lines used
by this technology.43 Consistent with our responsibilities for managing the interference potential of
devices which can interfere with radio under Section 302 of the Communications Act, we have developed


40 IEEE incorporated the in situ concept for deriving distance extrapolation from its earlier draft into
IEEE 1775-2010 IEEE Standard for Power Line Communication Equipment Electromagnetic Compatibility
(EMC) Requirements, Testing and Measurement Methods
, published on Jan 7, 2011.
41 A list of the parties submitting comments and/or replies is provided in Appendix A.
42 On Nov 30, 2011, ARRL also submitted ex parte comments (November 2010 ex parte comments) reiterating its
requests, with information from an ITU-R Report published in 2009 (ITU-R Report SM.2158 Impact of Power Line
Telecommunications Systems on Radiocommunications Systems operating in the LF, MF, HF and VHF bands below
80 MHz
), an ITU-T Recommendation published in 2009 (ITU-T G.9960 Unified High-speed Wire-line based Home
Networking Transceivers Foundation
), an OFCOM Report on The Likelihood and Extent of Radio Frequency
Interference from In-Home PLT Devices
dated Jun 21, 2010, and an IEEE Standard published in 2010 (IEEE
P1901-2010 Standard for BPL Networks: Medium Access Control and Physical Layer Specifications) that it
contends supports its position.
43 BPL Order at 21276.
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a set of rules for BPL devices and systems that attempts to minimize instances of interference while
allowing BPL systems to operate in a viable manner to serve the needs of the American public.44 In this
regard, we have stated and continue to hold that, on balance, the benefits of Access BPL for bringing
broadband services to the public are sufficiently important and significant so as to outweigh the limited
increase in potential for harmful interference that may arise. We also agreed with NTIA that while some
cases of harmful interference may be possible from Access BPL emissions at levels at or below the
Part 15 limits, the potential benefits of Access BPL service warrant acceptance of a negligible risk of
harmful interference that can be managed and corrected as needed on a case-by-case basis.45
15. To minimize the potential for harmful interference, facilitate its resolution where it may
occur, and address cases where its possible occurrence could impact critical services, we adopted
additional regulatory measures beyond the emissions limits in the Part 15 rules. These additional
measures generally require Access BPL operators to reduce emissions or avoid operation on certain
frequencies or in certain locations in order to protect licensed services, to use equipment that can alter its
operation by changing frequencies to eliminate harmful interference, to provide information that will
assist the public in identifying locations where Access BPL operations are present and provide notice to
radio users before commencing local BPL operations in a publicly accessible database. In this manner,
the Access BPL rules provide an effective means for limiting harmful interference and ensuring that any
instances of harmful interference that may occur can be quickly identified and resolved. As we
emphasized in the BPL Order, Access BPL systems will continue to be treated as unlicensed Part 15
devices and as such will be subject to the conditions in Section 15.5(b) of the rules that they not cause
harmful interference and that they cease operation if they do cause such interference, as required by our
rules.46 As discussed below, upon examination of the information and comments received in response to
the RFC/FNPRM, we continue to believe that these measures are adequate and appropriate for managing
the potential for harmful interference to all licensed radio services that operate on the bands used
internally by BPL systems, including the amateur radio service.
16. The requests for comment, explanation of rationale, and proposals presented in the
RFC/FNPRM were all raised to address further ARRL's concerns about the potential for BPL operations
to cause interference to licensed services, and specifically to amateur radio operations. The record
submitted in response to the RFC/FNPRM essentially consists of 1) a lengthy presentation by ARRL of
the reasons and arguments as to why it believes the information in the unredacted presentations and the
preliminary materials released in July 2009 show our rules for protection against BPL interference and the
extrapolation factor are based on incorrect or inappropriate analysis, technical explanations supporting its
positions, and requests for rule changes that it contends would "adequately protect" the amateur service;
2) statements from amateur licensees supporting ARRL's positions; 3) submissions from representatives
of the BPL industry opposing ARRL's positions on interference potential and rule changes and 4)
comments on our proposals for modifying the extrapolation factor and establishing a procedure for
determining site-specific extrapolation factors. Inasmuch as ARRL is the principal proponent of changes
to the BPL rules for interference protection and the extrapolation factor, and the principle respondent with
regard to the information in the unredacted studies and preliminary materials released in July 2009, we
focus the discussion on those subjects on its submissions and arguments.


44 47 U.S.C. 302. Section 302 states in relevant part that "[t]he Commission may, consistent with the public
interest, convenience, and necessity, make reasonable regulations (1) governing the interference potential of devices
which in their operation are capable of emitting radio frequency energy by radiation, conduction, or other means in
sufficient degree to cause harmful interference to radio communications ...."
45 NTIA comments filed June 4, 2004 in ET Docket Nos. 03-104 and 04-37, 19 FCC Rcd 3335 (2004), at
http://webapp01.fcc.gov/ecfs/document/view?id=6516212885, summary at iv.
46 47 C.F.R. 15.5(b).
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17. In its comments, ARRL argues in technical detail that BPL emissions propagate much
farther than our assessment indicates and that BPL operations therefore pose a much greater threat of
interference than that estimated by our analysis. It also asserts that the redacted portions of the staff
presentations reveal information that BPL operations cause absolutely preclusive interference and that the
Commission knew this information and ignored it.47 ARRL essentially contends that the amateur service
should be afforded protection against any possibility of interference occurring from BPL operations and
demands that BPL operations not be allowed on frequencies allocated to the amateur service.48 The
commenting parties representing BPL interests oppose ARRL's demands and support maintaining our
current rules. For example, CURRENT submits that "the record as a whole could plausibly have justified
a range of regulatory responses...and that the Commission's approach in the BPL Order enabling BPL
to go forward subject to unprecedented notching and shut-down requirements, as well as the 40
dB/decade extrapolation factor all come well within that range." It argues that nothing in the new
materials calls those positions into question.49
18. We are not persuaded by ARRL's newest technical submissions, including the
reports/standards referenced in its November 2010 and June 2011 ex parte comments, or its assertions
regarding the information in the unredacted presentations and in the additional information we recently
introduced into the record in July 2009 that our assessment of the interference potential from BPL
operations was incorrect or inappropriate, or that modifications to the BPL emissions limits and other
technical rules to provide additional protection for the amateur service are warranted. While there is
much valuable and valid information and analysis in ARRL's technical presentations, there are additional
considerations that previously led us to draw different conclusions and still lead us to maintain those
conclusions now.
19. With regard to the redacted portions of the staff presentations and the preliminary
information from early staff work that was released in July 2009, we were, of course, aware of that
content and we were also aware of other considerations and facts that bear on the various BPL technical
issues. Notwithstanding ARRL's apparent belief that the full content of the staff presentations should
have led us to the conclusion it prefers, we found, and continue to find, differently with respect to the
regulatory measures that are needed to protect the amateur service from interference from BPL
operations. The presentations in those informally conducted experiments were part of our initial internal
investigation of BPL and, while there is value in them, they are not the sole source of our information on
BPL performance. In this regard, we considered all of the available information on BPL systems and
their performance, submissions in the comments and other publicly available information. We also
observe that some of the staff presentations on which ARRL focuses were of experimental systems that
used early implementations of BPL equipment, developed before the BPL Order, that do not appear to
have complied with the new rules; additionally, information on other system implementations,
particularly our work with the Manassas, VA system, showed different performance characteristics than
the systems ARRL criticized. In some cases, ARRL simply (and incorrectly) draws different conclusions
from those presentations than we do. Also, the assessments and recommendations in the redacted
portions of the presentations merely reflect the views of the Laboratory engineers who performed the
testing and analysis; they do not necessarily reflect the consensus view of other engineers, the
management of the Laboratory or of OET. Indeed, individual views are often conflicting, but are
encouraged in the interest of producing vigorous debate to lead to a thoroughly considered
recommendation and decision.


47 ARRL comments, summary at 1.
48 Id. at 1.
49 CURRENT comments at 3.
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20. In the two sections of the discussion that follows, we address the potential for interference
and the measurement distance extrapolation factor, examining ARRL's arguments on each of the issues it
raises on those subjects and the responses of others in the comments. These issues concern: 1) the
potential for interference from Access BPL emissions to amateur communications, including the rate at
which the level of BPL emissions decline with distance from a power line as informed by the unredacted
technical presentations and preliminary materials released in July 2009; 2) the level of notching necessary
to protect amateur radio operations and whether to make notching mandatory on all amateur frequencies;
3) the technical considerations underlying the proper, i.e., "correct", value of the extrapolation factor used
to adjust emissions measurements made at distances less than 30 meters and other aspects of the BPL
measurement procedure and our request for comment on whether to reduce the extrapolation factor; and
4) establishing a procedure for determining site-specific extrapolation factors.

A.

The Potential for Harmful Interference

21. Overview. In the BPL Order, the Commission, with concurrence from NTIA,50 concluded
that the current emission limits will restrict Access BPL systems to low emitted field strength levels in
comparison to the signals of licensed radio operations. It found that the effect of these limits will be to
constrain the harmful interference potential of these systems to relatively short distances from the power
lines that carry the BPL signals. The Commission also recognized that some radio operations in the
bands being used for Access BPL, such as those of amateur radio licensees, may occur at distances
sufficiently close to power lines as to make harmful interference a possibility. The Commission stated
that it believed those situations can be addressed through interference avoidance techniques by the Access
BPL provider such as frequency band selection, notching, or judicious device placement, and it adopted
rules to facilitate such solutions.51
22. The Commission agreed with ARRL that Access BPL on overhead lines is not a traditional
point-source emitter, but not with its argument that Access BPL devices would cause power lines to act as
miles of transmission lines all radiating RF energy along their full length. In this regard, the Commission
observed that the Part 15 emission limits for carrier current systems have proven very effective at
controlling interference from such systems. Also, it indicated that the design and configuration of Access
BPL systems would be inconsistent with the development of cumulative emission effects for nearby
receivers. The Commission further concluded that because the BPL emissions level decreases
significantly with distance perpendicular from the line, the potential for interference also decays rapidly
with distance from the line.52
23. Notwithstanding the above considerations, the Commission recognized that Access BPL
systems present concerns for licensed users in the high frequency (HF) and lower portions of the very
high frequency (VHF) bands, given the propagation characteristics of RF signals in the range of
frequencies being used for these systems, the diversity of users of these frequencies, and the fact that
Access BPL devices could be installed at many locations in an area.53 While it concluded that there is


50 NTIA undertook a significant effort to both study Access BPL technology, including its operating characteristics
and interference potential, and to make specific recommendations to the Commission for policies to encourage its
implementation and to manage its interference potential in this proceeding. The Commission staff worked closely
with NTIA on this matter and the policy decisions and rules adopted for Access BPL reflect this cooperation and
embody many of NTIA's recommendations. BPL Order supra at 21266.
51 BPL Order at 21282.
52 Id., at 21282-21283.
53 The HF band covers frequencies from 3 to 30 MHz. The VHF band covers frequencies from 30 MHz to 300
MHz.
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little likelihood that harmful interference would occur from Access BPL operations at the signal levels
allowed under the current Part 15 emission limits, it acknowledged that such interference could occur in
limited situations despite the intentions of BPL operators. To address this interference potential, the
Commission required BPL operators to comply with additional interference mitigation techniques. It
stated that such steps should be taken particularly in those cases where the occurrence of interference
would affect critical services54 or where interference could be anticipated to occur. The interference
mitigation measures for critical services include exclusion from operating on certain frequency bands and
exclusion from operation in certain areas.55 For all services, the interference mitigation provisions require
that BPL system operators have the ability to remotely cease operation or apply frequency avoidance
(notching) on bands where licensed services are receiving interference. BPL operators were required to
be able to notch their operations on affected bands to a level 20 dB below the Part 15 emissions limit for
frequencies below 30 MHz (i.e., 1/100th of the emissions limits for other unlicensed unintentional
radiators).56
24. In the BPL Reconsideration Order, the Commission affirmed its selection of 20 dB below
the Part 15 emissions limit as the minimum notching capability for frequencies below 30 MHz.57 It also
revised the rules to specify that where an Access BPL operator implements such notching, the operator
need not provide further protection to mobile operations, nor will the operator be required to resolve
complaints of harmful interference to mobile operations by taking steps over and above implementing the
"notch." The Commission found that, while this level may be above the noise floor, reception of signals
in mobile operating conditions is generally not reliable at levels at or below that level and thus does not
warrant protection.
25. Comments/Discussion. In its comments, ARRL argues that recently released documents and
materials graphically and aurally reveal that Access BPL causes preclusive interference over very large
areas when such systems operate under current rules.58 It contends that, without substantial technical
limits that are not in the current BPL rules, Access BPL is incompatible with normal licensed amateur
radio communications. It asserts that all of the Commission's 2003 and 2004 presentations, including
both the unredacted presentations and the preliminary research materials released in July 2009, directly
controvert the conclusions that the Commission reached in the BPL Order and in the BPL
Reconsideration Order
and show that Access BPL has a significant harmful interference potential to
normal residential amateur radio operation.59 In this regard, it states that the presentations show that the


54 Some of these critical services include national defense, maritime distress and safety, aeronautical navigation and
communications, emergency response, and radioastronomy that provide important safety of life and research
services. See BPL Order at 21287.
55 For these services, ex post facto interference mitigation would not avoid potentially catastrophic results.
56 47 C.F.R. 15.611(c)(1)(i).
57 BPL Reconsideration Order at 9319-9320. The Commission observed that when extrapolated to values for the
typical distance of a mobile antenna from roadside power lines (approximately 6 meters horizontal distance and 8.5
meters vertical distance, for a slant range of 10.4 meters) and adjusted for the typical quasi-peak-to-average ratio of
4 dB for Access BPL devices operating at high duty factor, the Part 15 limit corresponds to a root-mean squared
(RMS) field strength of 44 dBV/m for frequencies at or below 30 MHz. A 20 dB reduction would limit emissions
to 24 dBV/m. BPL Reconsideration Order at 9318. See 47 C.F.R. 15.209(a).
58 ARRL comments, summary at 1.
59 ARRL also submits that the unredacted versions of the Commission's presentations contain numerous anomalies
and that it is not clear that the Commission has released the entirety of any of the presentations, because there are
gaps in the slide numbers. In his April 28, 2009 response to ARRL's FOIA request, OET Chief Julius Knapp
addressed this situation as follows: "Note that certain slide numbers and dates appear to be out of sequence, due to
(continued....)
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rules currently permit operation of BPL systems whose interference potential to amateur high-frequency
operation from Access BPL is essentially 100 percent at substantial distances from the power lines.60 In
support of its argument that there is significant potential for interference, ARRL submits technical
analyses describing why it believes the appropriate extrapolation factor for Access BPL emissions, which
is a function of the rate at which emissions attenuate with distance, should be 20 dB/decade rather than
the 40 dB/decade that has traditionally been used to extrapolate measurements of carrier current systems
for frequencies below 30 MHz to determine compliance with the Commission's emissions limits. To
avoid this interference, ARRL requests that the rules be amended to require mandatory notching of all
amateur frequency bands at notch depths of at least 35 dB below the level permitted under the Part 15
emissions limits (i.e., 1/5000th of the emissions limits for other unlicensed unintentional radiators).61 On
the other hand, the Utilities Telecom Council (UTC) contends that "the portions of the staff presentations
that were previously redacted are largely opinions that make observations, explain `caveats' in the data,
and provide options for the Commission to take."62 CURRENT states that "on the whole, the preliminary
data released in July 2009 have no significant effect on the Commission's earlier conclusions."63
26. In its November 2010 ex parte comments, ARRL reiterates its request for a requirement for
full-time mandatory notching of all amateur bands at a 35-dB notch depth, contending that this provision
can be implemented as part of the rules without any adverse impact on the BPL industry. In this regard, it
claims that the 35-dB notching capability is already a standard that is voluntarily in effect in most existing
BPL system architectures and deployments.64 ARRL cites a variety of recently published domestic and
international standards/reports that specify a 35-dB notching capability.65 However, in a May 2011 ex
parte
submission responding to this filing by the ARRL, UTC argues that contrary to ARRL's claims,
35-dB notching is not required by industry standards and requests that the Commission not impose such a
requirement because it would adversely impact BPL performance.66 It further states that one of the
standards referenced by ARRL, the IEEE P1901-2010, only refers to 35-dB notching with respect to one
type of BPL technology, wavelet OFDM.67 UTC asserts that wavelet OFDM technology's capability to
achieve notch depths of 35 dB is not representative of the performance of BPL systems in general. It
therefore argues that it would be misleading to suggest that 35-dB notching is required at all, much less
for BPL technologies in general. UTC further submits that a deeper notch depth generally requires wider
notch width, which means less bandwidth and lower speeds in terms of performance.68 UTC states that
(Continued from previous page)


repeat printing of files to generate unredacted versions of pages previously redacted." We would also point out that
these are not presentations that were intended for release and they underwent various revisions and modifications.
The versions provided in the record are the last drafts of those presentations and thus can be considered as the
"final" versions.
60 ARRL comments at 9, footnote 7.
61 Id. at 10.
62 UPLC comments at 2.
63 CURRENT comments at 2.
64 ARRL November 2010 ex parte comments at para. 3. As part of its comments, ARRL includes an Exhibit A
titled Rationale for Fixed 35-dB Notches for the Amateur Bands in Access and In-Premise Broadband over Power
Line (BPL) Regulations
, in which it outlines the electromagnetic compatibility (EMC) practices and standards that
the BPL industry has generally implemented to mitigate interference problems to the amateur radio service.
65 See footnote 42, supra.
66 See UTC ex parte comments (filed May 4, 2011) at 1.
67 IEEE P1901-2010, Standard for BPL Networks: Medium Access Control and Physical Layer Specifications.
68 Id. at 2.
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for these reasons the Commission should continue the current rules, rather than impose 35-dB notching.
27. In a June 2011 ex parte rebuttal to UTC's May 2011 submission, ARRL argues that UTC's
claims are in error because they are based on a selective interpretation and misstatement of the content of
the standards discussed and of the content of other sources that ARRL described.69 With respect to
industry standards, ARRL states that it reported on the notching required in a number of industry
standards, not just IEEE Standard 1901, and also reported on information published by or provided to
ARRL by BPL manufacturers, and on numerous measurements of BPL systems made by ARRL,
members of the BPL industry, regulators and other parties. It submits that in these sources, notch depth
was described or measured at depths ranging from 30 to over 40 dB. It agrees that some of those
standards and other sources cited in its November 2010 filing do not specifically mandate 35-dB
notching, and that in some of the sources it cited the stated notch is instead informative, and
demonstrative of the capability of the state of the art.70 ARRL submits that whether 35 dB is chosen for
the Commission's regulations, or 30 dB or 40 dB, is a secondary issue. It contends that the critical point
is that the state of the art of BPL system notching is far better than the 10- or 20-dB notching mandated in
the current BPL rules and that higher numbers on the order of 35 dB are achievable and can be
implemented without adverse impact on the technology, and that full time, mandatory notching with
substantially higher notch depths than are currently required by the Commission's rules are critical to
interference avoidance.
28. In response to UTC's statement that the 35-db notching described in IEEE Standard
1901-2010 applies only to wavelet OFDM BPL technology, ARRL states that UTC fails to note that this
standard applies to two BPL technologies, wavelet OFDM and FFT OFDM (HomePlug) and argues that
UTC hides the fact that the standard's requirements for FFT OFDM (HomePlug) BPL are very specific,
and normative, mandating a 30 dB spectral mask depth and normatively describing a "North America"
mask that includes the frequencies for the US Amateur bands.71 ARRL also disagrees with UTC that a
deeper notch depth affects the performance of BPL systems. In this regard, the ARRL submits the
findings of a study of In-House (in-building) BPL equipment by the European Telecommunications
Standards Institute (ETSI) that indicates that with notching, the overall trend is for a slight reduction in
data rate that is not harmful.72 ARRL further argues that the Republic of Korea has developed rules
requiring that the Amateur and aeronautical and marine safety bands be permanently notched and that
BPL systems are being successfully deployed in that country.73
29. We disagree with ARRL that the recently released materials show interference potential
from Access BPL systems to be significantly greater than that which we anticipated in the BPL Order,
that such interference will be preclusive of amateur operations over large areas, or that the current rules


69 ARRL ex parte comments filed Jun 24, 2011 (June 2011 ex parte comments).
70 See the list of sources cited by ARRL in footnote 42, supra.
71 ARRL June 2011 ex parte comments at p. 3-4. HomePlug is an industry standard for In-House BPL devices. See
http://www.homeplug.org/home/.
72 ARRL June 2011 ex parte comments at p. 9. ARRL cites ETSI technical report, ETSI TR102-616, PLT Report
from PlugTests 2007 on Coexistence between PLT and Short-wave Radio Broadcast; Test Cases and Results,
in
which test results on in-building BPL devices show 1) the loss of data was not substantial; 2) in some cases,
notching spectrum that is being affected by strong interference improved the data rate; 3) there is no consistency to
the degree to which notching affects the data rate (in either direction) relative to other factors such as conductor
losses and the physical architecture of the premise carrying the BPL signal; and 4) the data rate available to the end
user is affected by other factors (primarily the physical architecture of the local wiring carrying the BPL signal).
73 ARRL June 2011 ex parte comments at p. 10-11.
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are not adequate to resolve any interference that might occur. Rather, ARRL's in-depth focus on that
material is in some aspects consistent with our own assessments, in other aspects incorrect, and,
importantly, in many aspects does not account for the real world conditions affecting the propagation of
RF emissions at HF frequencies. While ARRL provides significant information on the standard
engineering principles concerning the attenuation rate of emissions from line emitters, it is mistaken as to
how the attenuation rate should be viewed for purposes of measuring BPL emissions. In this regard, we
again conclude that 40 dB/decade is a best estimate of the expected attenuation rate/extrapolation factor in
the conditions in which measurements are made under the Access BPL measurement guidelines. We find
no information in the comments or the newly submitted information in ARRL's November 2010 and June
2011 ex parte submissions that would warrant modification of the Access BPL rules to require notching
of all amateur bands at notch depths of at least 35 dB, or otherwise provide additional protection for the
amateur service. However, in reviewing the requirement that Access BPL systems be capable of reducing
their emissions by 20 dB in a given frequency band and current developments in BPL equipment, we now
find that it would be appropriate to increase this required "notching" capability by 5 dB, to 25 dB for BPL
systems operating below 30 MHz. We respond to the comments with respect to each of these sets of
materials sequentially below.
1.

Unredacted Staff Presentations and Newly Submitted Materials

30. In its comments, ARRL argues that the unredacted staff presentations show that:
1) Access BPL is not a point-source emitter; it is a distributive system that has significant
interference potential over a wide area at significant distances from (and along) the power line
carrying BPL signals. It contends that the Commission's measurements show that there is
virtually no signal decay along the power line 230 meters from the coupler.
2) The proper distance extrapolation factor for assumed signal decay with distance from the
power line is much closer to 20 dB/decade of distance (20 log R) than to the 40 dB/decade of
distance (40 log R) adopted by the Commission for frequencies below 30 MHz.
3) Access BPL has a considerably higher interference potential to licensed radio services than the
Commission concluded in the BPL Order if operated at the maximum radiated emission levels
permitted by the Commission's Part 15 rules (and the BPL rules adopted in the BPL Order).
Specifically, interference to licensed mobile radio receivers is very likely for very long distances
along a power line. The presentations also show that systems operating at the Part 15 emission
limits will be at least 25-35 dB stronger than the median values of man-made noise at 30-meters
distance. Extrapolating this to a mobile antenna closer to the lines results in an even higher noise
level.
4) The Commission erred in concluding that mobile Amateur stations would be protected from
interference if, in response to an interference complaint, the BPL operator reduced the BPL
radiated emission level from the offending portion(s) of the BPL system by 20 dB below the
maximum radiated emission level permitted for Part 15 devices generally. That remedy falls far
short of reducing BPL noise to the level of ambient noise in residential environments found by
Commission's technical staff, and falls far short of reducing BPL wideband noise levels to the
point that mobile communications can be conducted in areas substantial distances from the power
line.
5) Measurement of BPL radiated emissions should be done at heights not lower than in the same
horizontal plane as the overhead power line.
31. First, we agree with ARRL that a BPL system does not behave as a point-source emitter.
Neither, however, can it be analyzed as a line emitter. Analysis and prediction of RF propagation in the
HF frequency region is extremely complex and difficult, and particularly at locations close to the ground,
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as the Commission, ARRL and many other commenters have acknowledged throughout this proceeding.74
Our intent in the BPL Order was not to say that power lines are point-source radiators, but rather simply
that the interference potential lessens with distance down the line from the coupler -- though this occurs
at rates that can vary significantly with power line topology.
32. ARRL points out that one of the video files in the staff materials released by the
Commission in July 2009 shows interference to mobile reception of signals in the amateur 20-meter band
(14.0-14.35 MHz). Specifically, it states that the video of the Briarcliff Manor system recorded on
August 17, 2004 (Briarcliff Video #5) shows in a graphic, compelling manner the severe and constant
interference caused by the BPL system to amateur reception over huge geographic areas which obviously
precluded essentially all Amateur HF communications in the area. It submits that no objective observer
of this video could possibly conclude that the level of BPL radiated emissions permitted by the
Commission's Part 15 rules is acceptable. ARRL is correct that the interference that is apparent on
Briarcliff Video #5 is not acceptable and would not be permissible under either our Part 15 rules or the
system operator's experimental license.75 However, while interference can occur from BPL operations
along a stretch of power lines as shown in that and other videos in the preliminary materials released in
July 2009, we did not and do not find this example to substantiate a need for more restrictive rules on
BPL systems. First, it does not appear that any of the mitigating features that are required in the rules had


74 Access BPL systems operating on overhead power lines do not act as point sources. The operation of these
systems depends on injecting BPL-modulated radio-frequency (RF) energy that travels down the power lines for
detection by subsequent BPL devices. The BPL RF current and voltage carried by the power lines cause RF
emissions from the power lines -- not just from the BPL couplers. The ARRL correctly notes that in some cases
BPL emissions may exhibit relatively little decay 0.5 mile downline from the coupler, though in other cases the
decay can be much more rapid, e.g., as shown on slide 8 of BPL Summary After Briarcliff Manor, NY Test. In
general, one would expect those RF emissions to gradually diminish with distance downline from the coupler as
energy is lost to resistance in the power line conductors and correspondingly to emissions from the power lines. In
addition to this gradual decay with distance downline, a more abrupt drop in RF energy on the power line is
expected to occur when the power line splits between two branches, e.g., continuing down the same street in
addition to branching down a side street. Such a branch splits the RF energy between the two branches and also
causes an impedance mismatch that reflects some of the energy back toward the BPL coupler. Both the splitting of
energy between the branches and the reflection of some of the energy back toward the coupler cause an abrupt
reduction in the RF current that continues down the power line away from the coupler. This reduction in current is
accompanied by a reduction in emissions from the portions of the power line beyond the split. In addition, the
energy directed back toward the coupler by reflection causes standing waves, which can cause the emissions from
the power line to alternately increase and decrease at various points along the line. (Connection from an overhead
line to feed an underground cable results in an even larger impedance mismatch and a larger reflection of the
incident RF energy.) Consequently, one can expect that the RF emissions from the power line may alternately
increase and decrease in moving down the power line, but with a gradual overall decline with distance downline
from the coupler and with occasional step-change reductions in emissions caused by impedance mismatches and
branches. These various effects contribute to a net -- but erratic -- reduction in RF signal level on the power line
with distance downline from the coupler. These effects are the cause of both the need for repeaters to boost the level
of BPL signals in order to enable the systems to function properly and the decay in interference potential of BPL
emissions with distance downline.
75 The Briarcliff Manor Access BPL system was operated under an experimental license and therefore not subject to
the Section 15.209 emissions limit. It was, however, subject to a non-interference requirement. See 47 C.F.R.
15.209. We also note that in its reply comments, CURRENT observes that ARRL, on the one hand, in a December
28, 2005 report of its measurements on the Briarcliff test, (http://www.arrl.org/tis/info/HTML/plc/filings/Briarcliff-
Compliant-Engineering-0106.pdf) complains that the system was out-of-compliance with the rules. It submits that
ARRL cannot both complain that a system is out-of-compliance and yet also use interference from that system as
evidence that the rules are inadequate. CURRENT reply comments at 7. We agree and our assessment of the
interference potential of a compliant system and the effectiveness of the Part 15 emissions limit in controlling
interference is not based on the performance of the Briarcliff Manor system.
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been applied to this system.76 In addition, our staff did contact the licensee about interference from that
system several times over the course of its operation and the operator took steps first to cease operation on
the amateur frequencies and then to install new equipment that had notching capability.77 Subsequent
examination of that system by field agents of our Enforcement Bureau found no interference, which
substantiates the effectiveness of our rules when properly observed.78 Also, as indicated by the primary
and secondary title screens of Briarcliff Video #5, the system was notched only in the 20-meter amateur
band, and not in the 15-meter amateur band, for which that video was recorded.79 Thus, we did not and
do not consider the interference that appears in Briarcliff Video #5 to be representative of the
performance of a system operating in accordance with the set of rules we set forth for Access BPL
systems.
33. We also see no merit in ARRL's argument that statements on the same presentation slide
concerning an interference problem from the Phonex carrier current system to ARINC aeronautical
communications and opining that compliant Access BPL "may be worse" should have served as a factor
in our decision on protection for the amateur service. In the BPL Order, we recognized the critical nature
of aeronautical communications and, given the free space propagation path from a power line to an
aircraft, excluded Access BPL systems from operating on frequencies used by that service.80 With respect
to the Phonex case, we also observe that the Phonex system at issue might not have been the source of the
interference with ARINC's communications and its performance therefore cannot be used as an empirical
basis for establishing any benchmarks with respect to the interference potential of BPL systems.81
34. ARRL next observes that another presentation slide in the Briarcliff Manor presentation
recommends that the Commission "impose [a] 5 dB height correction [factor]" on measurements and a
"20 log R extrapolation factor" if it is going to allow BPL on medium voltage (MV) overhead power lines
and should use a 20 dB/decade extrapolation factor for signal decay with distance from the power line.82
It observes that the presentation states that this "reduces interference [from BPL] to fixed stations."
Basing the BPL emissions limits and measurement procedures on an attenuation rate of 1/R, i.e.,
20 dB/decade would, of course, reduce signal levels and thereby provide additional protection to licensed
services against interference. We note that the slide in question does not provide a "recommendation" as
claimed by ARRL, rather, it only presented several options for other staff and management to consider in
its deliberations. Further, as we concluded previously, we do not believe that such additional protection is
needed or warranted, but rather hold that the Part 15 "no interference requirement", the Part 15 emissions
limit for carrier current systems, and the interference mitigation measures we adopted in the BPL Order


76 Note that at the time of all of the testing recorded in the recently released documents, the Commission had not yet
adopted any of the interference mitigation requirements on Access BPL systems, such as dynamic notching and
remote shut-down.
77 See Letter dated February 10, 2005 from Bruce Franca, Deputy Chief, Office of Engineering and Technology, to
Christopher Imlay, ARRL.
78 Id.
79 See also the "Briarcliff Manor BPL Video Files" description in the preliminary materials released in ET Docket
No. 04-37 on July 17, 2009.
80 See BPL Order at 21287.
81 See Memorandum from Joseph Casey, Chief, Spectrum Enforcement Division, Enforcement Bureau, to Bruce
Franca, Deputy Chief, Office of Engineering and Technology, dated January 27, 2004, in ET Docket Nos. 03-104
and 04-37, at http://fjallfoss.fcc.gov/ecfs2/document/view?id=6516083908; see also, comments of Phonex
Broadband Corporation on this subject at http://fjallfoss.fcc.gov/ecfs2/document/view?id=6515683343.
82 ARRL comments at 28; Briarcliff Manor presentation summary at slide 19.
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collectively provide sufficient protection to licensed services from the potential for harmful interference
from Access BPL operations. As discussed below, we also continue to find that the attenuation rate of
emissions from power lines is typically higher than 20 dB/decade and varies with location. At distances
within 30 meters of the power line and when using the slant-range measurement procedure prescribed in
our measurement guidelines, 1/R2, i.e., 40 dB/decade, properly describes the expected attenuation rate at
frequencies below 30 MHz, and variability around that rate is also expected.
35. It is also important to understand, as we discussed in the RFC/FNPRM and ARRL largely
ignores, that RF propagation in the lower frequencies ranges, and particularly at frequencies below 30
MHz, is greatly affected by environmental factors, so that there is significant variability in propagation
from place to place. These include ground absorption and conductivity, terrain, vegetation, and the
presence of structures and other man-made objects, including additional power lines arrayed on
pole/towers in the near-field of emissions from a power line carrying Access BPL transmissions. In some
cases, emissions from BPL systems that are expected to be compliant with the rules will attenuate with
distance at relatively high rates and be well below the Part 15 limits while emissions from other systems,
or even from the same system but at a different location, will attenuate at a relatively lower rate and
exceed the Part 15 limits. We are aware of these variabilities in this complex operating environment and
to account for it, we adopted the additional provisions for mitigating harmful interference that are set
forth in the rules. In addition, recognizing this variability, we did not base our assessment of interference
potential on any standard performance factor, such as an attenuation rate by itself, but rather on the
successful past performance of our existing standards and the availability of suitable approaches for
managing the potential for harmful interference and correcting any harmful interference that may occur.
36. We have also fully considered the issue of how to measure Access BPL emissions, including
whether a 5 dB correction factor was needed for Access BPL measurements below 30 MHz. In the BPL
Order
, we concluded that the existing measurement procedure that provides for measurement of the
magnetic field at 1-meter height with no correction factor was appropriate for measurements in that
frequency region.83 There is no additional information in the presentation summaries that leads us to find
that this decision should be changed.
37. ARRL points out that slide 20 of the Briarcliff Manor presentation listed options of notching
or mandatory advance coordination for protection of low-VHF public safety channels and that the


83 See BPL Order at 21303-21310. In its May 2004 comments in this proceeding addressing the Commission's
proposed measurement guidelines later adopted, ARRL supported a measurement height of 1 meter with the use of a
loop antenna to measure magnetic fields, stating that "ARRL has done antenna modeling that shows that the
magnetic field will typically vary approximately 3 dB with height..." See ARRL comments filed May 3, 2004,
Exhibit D at page 28, at http://webapp01.fcc.gov/ecfs2/document/view?id=6516182983. According to this
submission, the maximum value is found at power line heights of 18 meters above ground, a height much higher
than typical power line heights of 10-12 meters. For example, Figure 5 of Exhibit D shows only a 1.4 dB difference
in the H-field intensity between a measurement at 1 meter and a measurement at a power line height of 11 meters,
for 14 MHz. Further, ARRL agrees that measurements at such height, or even at typical power line heights of 10-12
meters, are neither practical nor safe. However, in its subsequent reply comments in the same time frame (filed June
2004), ARRL then agreed with NTIA's suggestion for a 5-dB height correction for measurements below 30 MHz
(which NTIA itself later dropped based on subsequent studies, see NTIA supplemental comments filed Sep 24, 2004
at 3). Nonetheless, ARRL did not submit any data to the contrary to rebut its own previous submissions that the
magnetic field does not vary much with height, especially at typical power line heights of 10-12 meters, obviating
any need for a height correction factor for frequencies below 30 MHz. In its ex parte comments filed on January 11,
2010, ARRL again reiterated its demand for a height correction factor, stating that most standards require the use of
a height-scanning antenna mast, but neglected to address that emission measurements below 30 MHz are made with
a loop antenna and that its earlier modeling data and conclusions support the findings from NTIA and from the
Commission that no height correction factor is necessary for frequencies below 30 MHz.
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Commission did not adopt either of those options but instead put in place a notification requirement.84 It
also observes that the same slide listed the 50-54 MHz amateur band that is typically used for both mobile
and fixed operations and the Commission did not acknowledge the interference potential to amateur
operations in that band and offered no remedy for it. In the BPL Order, we determined that public safety
systems, because of the often critical and/or safety-of-life nature of the communications they provide,
merit the additional protection of advanced notice of BPL operations. We stated that an advance
notification would provide a public safety operator with an opportunity to assess whether there are
portions of its geographic area of responsibility about which it should make special arrangements with the
Access BPL operator in order to avoid interference.85 We did not address the frequencies used by the
amateur service on an individual basis, but rather concluded that amateur radio frequencies generally do
not warrant the special protection of frequency exclusion that was afforded frequencies reserved for
international aeronautical and maritime safety operations.86
38. ARRL observes that slide 21 of the Briarcliff Manor presentation predicts the potential for
BPL to cause interference to mobile operations to be "high" to "very high." It further observes that the
same slide has a table indicating that the interference distance to fixed stations would be 62 meters at
2-8 MHz and 400 meters at 8-30 MHz in areas where the noise levels were at the International
Telecommunication Union (ITU) "residential" level.87 It contrasts these statements with our findings in
the BPL Order that the potential of Access BPL systems was "low" and observes that in the case of
mobile communications where a vehicle is close to the power lines, the potential for interference will
indeed be higher. While we again recognize that at some locations (including where nearby antennas are
located above the height of the power line) the attenuation rate of Access BPL emissions will be lower
and at other locations it will be higher, these levels are consistent with our interpretations that the
interference potential is low such that it can be managed adequately with the additional interference
mitigation measures and the "no harmful interference provisions" of Part 15 that are also in our rules.88 In
this regard, the distances from a power line to an amateur fixed receiver will be sufficiently short that if
harmful interference were to occur, the recipient could readily identify its source and request that it be
resolved. We observe that International Broadband Electric Communications, Inc. (IBEC), a major
operator of Access BPL systems, reports (with confirmation by ARRL in its comments) that it has been
communicating with the local amateurs and emergency services in the areas it covers to implement a
successful interference resolution process.89 It states that it has been able to resolve interference
complaints, as they arise, under the framework of the existing Access BPL rules. This information
provides confirmation that the processes and requirements we established, when used in practice, are
adequate to prevent most cases of harmful interference to licensed services, and to resolve quickly any
instances of harmful interference that do occur.
39. Spectrum Notching. The rules provide for mitigation of BPL interference where it may
occur by notching. In the BPL Order and the BPL Reconsideration Order, the Commission found that,
for frequencies below 30 MHz, a 20-dB notch would appropriately address any harmful interference that


84 ARRL comments at 29-30.
85 BPL Order at 21288-21289. Section 15.615(e) requires that notifications of Access BPL operations be provided
to local public safety agencies at least 30 days prior to a system's initial operation.
86 ARRL had requested that the Commission include the amateur HF and VHF allocations with other bands that
NTIA determines require protection from BPL interference. BPL Order at 21289.
87 See Briarcliff Manor presentation summary at slide 21.
88 47 C.F.R. 15.5.
89 IBEC comments at 2; see also ARRL reply comments at 3-4.
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might occur to mobile operations, given both the low signal levels allowed under the Part 15 emission
limits and the fact that a mobile transceiver is generally only in one place for a limited period and can
readily be re-positioned to provide some separation from the Access BPL operation.90
40. In its comments, ARRL argues that slide 13 of the Briarcliff Manor presentation summary
references predictions from the NTIA Phase 1 Study that show that the noise floor would rise by more
than 20 dB at nearly all points, and by 30 dB at most points, along a 340-meter modeled power line. It
also notes that the slide states that in NTIA's measurement activities, NTIA took occasional samples of
noise power along the line with the Access BPL system turned off and found noise levels lower than
predicted by the ITU for residential areas.91 ARRL therefore contends that the 20-dB standard for the
notching requirement is insufficient.92 We initially note that NTIA's sampling of noise power was only at
a very limited number of locations and not sufficient to serve as the basis for a conclusion that the noise
floor is lower than the levels recognized by the ITU.93 Further, as discussed below, there is not sufficient
information in any of the submissions regarding changes in the noise floor to justify a change from our
use of the well-established ITU-recommended levels for the noise floor in different environments.
41. In its November 2010 ex parte submission, ARRL provides additional comments94 that
reference several recent domestic and international industry and governmental reports/standards to
support its request for a 35-dB notch of all the amateur frequency bands. These documents include: 1)
ITU-R Report SM.2158;95 2) ITU-T G.9960;96 3) IEEE P1901-2010;97 and 4) OFCOM Report on In-


90 BPL Order at 21294 and BPL Reconsideration Order at 9318.
91 The ITU's expected noise power levels are set forth in ITU-R Recommendation P.372-10 Radio Noise.
92 ARRL comments at 36.
93 We also note that in the same report, NTIA concludes that "the results for the vehicular mobile receiver predict
that the received BPL signal power near the Earth surface falls off rapidly with distance from the lines. The
distances within which these thresholds were exceeded at fifty percent of locations were modestly smaller at a third
frequency (4 MHz) and much smaller at the fourth frequency (40 MHz). In all land vehicular cases considered,
reductions in S/N were less than 3 dB and 10 dB beyond one-hundred-and-twenty-five meters and fifty-five meters,
respectively." NTIA Report 04-413, "Potential Interference From Broadband Over Power Line (BPL) Systems To
Federal Government Radiocommunications at 1.7 - 80 MHz
," Phase 1 Study, Volume 1, April 2004 (NTIA Phase 1
Study
), at 23.
94 ARRL November 2010 ex parte comments at Exhibit A.
95 See Impact of Power Line Telecommunications Systems on Radiocommunications Systems operating in the LF,
MF, HF and VHF bands below 80 MHz
, International Telecommunications Union (ITU) Report SM.2158, 2009.
This report covers the use of the radio spectrum and associated interference protection requirements of
radiocommunication services operating below 80 MHz with respect to the impact of BPL systems as part of the
International Telecommunications Union studies on the compatibility between radiocommunication systems and
high data rate telecommunication systems using electricity power supply or telephone distribution wiring. See
http://www.itu.int/pub/R-REP-SM.2158/en.
96 See Unified High-speed Wire-line based Home Networking Transceivers Foundation, ITU-T G.9960, 2010.
This ITU Recommendation specifies the system architecture and physical (PHY) layer for wireline-based home
networking transceivers capable of operating over premises wiring including inside telephone wiring, coaxial cable,
and power-line wiring. Transceivers defined by this Recommendation use OFDM-type modulation and are designed
to provide EMC and spectral compatibility with other devices sharing the in-premises wiring. See
http://www.itu.int/rec/T-REC-G.9960-201006-P.
97 See Standard for BPL Networks: Medium Access Control and Physical Layer Specifications, IEEE P1901-2010.
This standard provides specifications for several of the BPL existing OFDM protocols, essentially a multi-carrier
(continued....)
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Home PLT devices.98 All of these documents mandate or recommend notching of the amateur
frequencies.99 ITU-R Report SM.2158 states that the maximum allowable increase in the noise floor100
due to BPL emissions should not exceed 0.5 dB, based on the assumption that the fade margin101 of the
amateur service in long distance communications is less than 1 dB.102 Based on this assumption, ARRL
argues that a notch depth of 34 dB would be required if a 20-dB/decade extrapolation of the FCC
emission limits is used and a notch depth of 43 dB would be needed if the existing extrapolation factor of
40-dB/decade is used.103
42. In re-examining all of the information pertaining to the depth of the notching requirement,
we now find that it would be appropriate to increase the required notching capability to be 5 dB greater
than the 20 dB specification we initially adopted. Previously, we observed that when operating with a
20-dB notch below 30 MHz, the maximum allowed emissions from an Access BPL system is 10 dBV/m
at the Part 15 measurement distance of 30 meters, a level which is at or only modestly above the noise
(Continued from previous page)


technique that spreads data among multiple carriers to allow a more robust operation in a noisy environment. See
http://grouper.ieee.org/groups/1901/.
98 See The Likelihood and Extent of Radio Frequency Interference from In-Home PLT Devices, OFCOM Report,
June 21, 2010. This report focuses on In-House BPL devices in the United Kingdom, concluding that the notching
of international amateur frequencies combined with interference mitigation features such as power control and smart
notching would be sufficient to reduce interference to negligible levels. See ARRL November 2010 ex parte
comments at Exhibit G.
99 Concerning the level of notching needed, the ITU-T 9960 Recommendation specifies 30 dB notching of In-House
BPL systems for compatibility with amateur radio services. The OFCOM Report, which focuses exclusively on In-
House BPL devices, indicates that although smart notching capabilities (between 30 and 40 dB) are already part of
the product roadmaps of the BPL vendors that were consulted as part of the study, it is recommended that where
possible the introduction of these features be formalized. The IEEE P1901-2010 Standard provides for 35-dB
notching for both In-House and Access BPL devices. The ITU-R Report SM.2158 does not specifically recommend
a particular notch depth with respect to compatibility with amateur radio services, but states that "the maximum
allowable increase in the total noise floor due to [BPL] emissions should be 0.5 dB." ITU-R Report SM.2158 at p.
35.
100 ITU-R Report SM.2158 at p.36-37. The noise floor figures are derived from Recommendation ITU-R P.372-10
(2010) Radio Noise. See http://www.itu.int/rec/R-REC-P.372/en. In its June 2011 ex parte comments, ARRL also
mentioned ITU Recommendation SM.1879 that refers to the SM.2158 report with respect to the increase in the noise
floor.
101 "Fade margin" refers to the amount by which a received signal level may be reduced without causing system
performance to fall below a specified threshold value.
102 ITU-R SM.2158 at p. 35.
103 See ARRL November 2010 ex parte at Exhibit A, p. 29. ARRL also includes in this ex parte additional Exhibits
B through G that show operation of BPL systems with 35-dB notching and certain other information relating to its
position that BPL poses a threat of interference to amateur operations. Exhibit B is a copy of a joint report issued in
2001 by HomePlug and ARRL with respect to the cooperative tests and development of the HomePlug standard for
In House BPL which incorporated 30 dB notches in amateur bands. Exhibit C is a copy of a news article released in
2006 discussing a demonstration at ARRL's headquarters of the notching efforts made by Spanish BPL chip
manufacturer DS2 to avoid interference to amateur radio services. Exhibit D is a description of errors found in the
BPL database maintained by UPLC, which ARRL has also identified in its comments (filed Sep 23, 2009). Exhibit
E is a report commissioned by IBEC in 2004 to show that spectrum notches for the Amateur bands were
implemented at an IBEC deployment in Cullman, AL. Exhibit F is a test report made by the Albermarle Amateur
Radio Club in 2004 on another IBEC BPL system in Nelson County, VA, showing test results on spectrum notches
in various amateur bands. Finally, Exhibit G reproduces an OFCOM report dated Jun 21, 2010 that studied the
interference potential of In House BPL devices on radio services in the HF and VHF frequencies in the U.K.
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floor in the HF bands at most locations.104 That is, our intention was that Access BPL emissions in a
notched bandwidth would not be significantly greater than the background noise at the distances normally
used for protection against harmful interference from Part 15 unlicensed devices. We also evaluated the
potential for interference at closer distances that can occur when conducting mobile communications
while traveling adjacent to roadside power lines. We observed that when extrapolated to values for the
typical closest distance of a mobile antenna in motion from roadside power lines (approximately 6 meters
horizontal distance and 8.5 meters vertical distance, for a slant range of 10.4 meters) and adjusted for the
typical quasi-peak to average ratio of 4 dB for BPL devices operating at high duty factor, the Part 15 limit
corresponds to a root-mean-squared (RMS) field strength of 44 dBV/m for frequencies at or below
30 MHz. A 20 dB reduction would limit emissions to 24 dBV/m. We concluded that given the high
variability of the noise floor at HF frequencies, where increases of as much as 20 dB or more are
common, mobile reception of relatively weak signals under 24 dBV/m is generally intermittent and not
reliable because both the received signal and the ambient noise levels vary up and down (the received
signal and noise energy levels generally do not rise and fall together) as the vehicle moves.
43. In carefully reviewing the record on this issue, we acknowledge ARRL's point that the
modeling in the NTIA Phase 1 Study predicts that Access BPL emissions on frequencies below 30 MHz
that are at the Part 15 limit would raise the mobile radio noise floor at 15 MHz and 25 MHz by 30 dB in
59% of residential locations.105 After a 20-dB notch, the BPL remaining emissions would still produce a
noise floor increase of about 10 dB for mobile operations in residential locations at those frequencies. As
we observed in the BPL Reconsideration Order, there is considerable variability around the median noise
level, such that increases of as much as 20 dB are common and reduce the reliability of signals at the
margin of expected reception.106 While we continue to believe that the significant variability in
background noise levels limits the reliability of HF signals below 30 MHz such that BPL emissions at a
level of 24 dBV/m should not generally be considered harmful interference, we also understand that the
20 dB value for noise increases due to diurnal and seasonal factors is the maximum expected effect and
that in many cases the daily variability in the noise floor levels will be somewhat less. We have no
specific information on the distribution of the diurnal and seasonal variability of noise floor levels;
however, we believe that an increase of 5 dB in the required notching capability, or half the 10-dB current
margin of BPL emissions affecting mobile reception above the residential noise floor, according to
NTIA's estimates as supported by ARRL, would take a more conservative approach and provide


104 BPL Order on Reconsideration at 9319-9320. The nominal noise floor in the HF band, as recognized by the
International Telecommunications Union, varies with frequency and population/commercial density (values are
provided for business, residential, rural, and rural quiet areas). For reception with a short vertical monopole, the
ITU median noise levels are 10 dBV/m, 5 dBV/m, 0 dBV/m, and -7dBV/m in business, residential, rural, and
rural quiet areas, respectively, in a 9-kHz bandwidth at 30 MHz (at lower frequencies the ITU median noise levels
increase on a sliding scale). The Part 15 radiated emission limit for Access BPL and other carrier current systems is
30 dBV/m quasi-peak in a 9 kHz bandwidth at 30 meters for frequencies at or below 30 MHz, see 47 C.F.R.
15.611(a).
105 NTIA Phase 1 Study, Volume I, Table 6-3. These predictions assume that mobile operations occur at a distance
of 15 meters horizontal distance from the power lines. The increase in the noise floor is different at different
frequencies below 30 MHz. For example, the same table in the NTIA Phase 1 Study shows that a 30 dB noise floor
increase at 4 MHz only occurs in 6% of residential locations.
106 See e.g., comments of NTIA in response to the BPL Notice of Proposed Rule Making (filed Sep 8, 2004), in
which it states that "[p]ower line noise resulting from ingress of ambient radio noise can vary by upwards of 20 dB
throughout the day and seasonally, especially at frequencies below 12 MHz." NTIA comments at 9. In addition, the
ITU-R Rec. P.372-9 information on the values of decile deviations of man-made noise, showing combined
variability with location and time of 19.4 dB, 16.4 dB and 16 dB in business, residential and rural environments,
respectively. See ITU-R Recommendation P.372-9 (2007), Radio Noise, Table 2, at p. 15.
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protection for amateur mobile operations in more instances, while continuing to recognize the variability
in emissions that limit the service to mobile amateur receivers.107 Given our understanding supported by
the assertions in the record that most BPL operators are already using notches of at least 25 dB, we would
expect the cost imposed by this requirement to be minimal or nil. We find that the benefits of providing
additional protection for licensed services outweigh any potential additional costs to BPL providers. Such
benefits include a more integrated environment where BPL devices may share spectrum with licensed
users, with lesser concerns for potential harmful interference. BPL devices bring expanded benefits to
electric utility companies by allowing them to monitor, and thereby more effectively manage their electric
power distribution operations.108 BPL also brings "last-mile" delivery of broadband services to some
rural and underserved areas.109
44. With respect to the new information in ARRL's November 2010 ex parte submission, we
first are not persuaded that a 0.5 dB increase in the noise floor as used in the ITU-R Report SM.2158 is a
reasonable assumption for the numerous reasons we stated above with respect to the significant variability
in background noise levels at HF frequencies.110 Further, it appears that the 0.5 dB number was used in
the ITU Report without any discussion, analysis or other explicit rationale. We further note that in its
June 2011 ex parte submission, ARRL mentions that ITU-R Recommendation SM.1879,111 which refers
to the above report, does recommend that stations operating in the Amateur Service be protected to a level
such that noise at the protected station is not increased by more than 0.5 dB.112 Although ARRL provided
calculations to relate the 0.5 dB increase in the noise floor with the Part 15 limits to arrive at its requested
35-dB notch number, it again did not provide a rationale for using a 0.5 dB increase in the noise floor as
the protection criterion at HF frequencies. With the exception of ITU-R Report SM.2158, the
reports/standards submitted by ARRL in its November 2010 ex parte comments do not include any
analysis that shows that 35 dB or some other figure is the proper level of notching needed to protect
amateur operations, but rather simply state as their recommendations/requirements a notching depth that
existing BPL equipment can meet. We also recognize the ARRL's observation in its June 2011 ex parte
submission that in the IEEE P1901-2010 standard there is a normative requirement for a 30-dB notch
depth for the FFT OFDM (HomePlug) technology.113 While this voluntary industry standard is
apparently being used by manufacturers of HomePlug In-House BPL equipment, it is more stringent than


107 In our previous decisions, we have assumed that mobile operations occur at a distance of 6 meters horizontal
distance from the power lines. Following the analysis set forth in the BPL Reconsideration Order, at the shorter
6-meters distance, a 5-dB increase in an Access BPL notch will leave a margin of approximately 15 dB above the
residential background noise level.
108 See IBEC Smart Grid solutions at http://www.ibec.net/services.php; Amperion Smart Grid solutions at
http://www.amperion.com/solutions.php.
109 See IBEC High Speed Internet services to rural Americal at http://www.ibec.net/services.php.
110 We note that ITU-R Recommendations are not binding on the Commission. Amendment of Parts 2 and 25 of the
Commission's Rules to Permit Operation of NGSO FSS Systems Co
- Frequency with GSO and Terrestrial Systems
in the Ku
- Band Frequency Range, Memorandum Opinion and Order and Second Report and Order, ET Docket No.
98-206, 17 FCC Rcd 9614, 9631 (para. 41) (2002) ("[R]ecommendations resulting from ITU-R deliberations are not
necessarily binding for purely domestic allocation decisions . . . ."). See also Revision of Part 15 of the
Commission's Rules Regarding Ultra-Wideband Transmission Systems, Third Memorandum Opinion and Order
, ET
Docket No. 98-153, 25 FCC Rcd 11390, 11393 n.16 (2010).
111 See ITU-R Recommendation SM.1879, The impact of Power Line High Data Rate Telecommunication Systems
on Radiocommunication Systems below 30 MHz.

112 ARRL June 2011 ex parte comments at p. 4.
113 Id., at p. 3-4.
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is necessary for our regulatory purposes as discussed above and in any case does not apply to the Access
BPL applications at issue herein. We also do not find persuasive ARRL's argument that deeper notching
can be implemented without adverse impact on the data rates of BPL technology. In this regard, the
testing on which ARRL bases this claim was on In-House rather than Access BPL equipment and in any
case our principal concern is with imposing regulation that is more restrictive than necessary rather than
simply minimizing the impact that such regulation might have on some aspect of BPL equipment or its
operation. While we duly note the Republic of Korea's decision to require permanent notching of the
amateur bands, the relevance of that determination by that country's regulatory body at that time to our
present consideration is not readily apparent, and ARRL provides no information regarding either the
radio environment or the regulatory objectives and standards that informed that decision by which we
might consider how those considerations might affect our own decision making.
45. We recognize that one of the documents referenced by ARRL, IEEE P1901-2010, is an
industry standard for both Access and In-House BPL equipment authored by nearly a hundred entities that
include BPL service and equipment providers and that this standard describes a 35-dB spectrum notching
for compatibility with amateur radio services that can be supported by a type of BPL technology known
as wavelet OFDM, as elucidated by UTC.114 Further, as ARRL submits, its scrutiny of systems listed in
the BPL database indicates that existing BPL systems in the U.S. are generally notching the entirety of the
HF amateur allocations, using equipment capable of notch depths of at least 35 dB.115 Thus, it appears
that many BPL systems now in operation may be voluntarily observing the notch depth and band
avoidances that ARRL is requesting. While those industry practices are consistent with the ARRL's
goals in this matter, we nonetheless find they are more stringent than are justified from a regulatory
standpoint.116 In this regard, we do not find that an increase in the required notching capability to a level
above 25 dB is needed to protect against interference to amateur or any other licensed services. To
require that all systems adhere to a de facto industry 35-dB notching standard would unnecessarily
constrain BPL operators, as stated by UTC, and equipment manufacturers who might choose to design for
a different level of operation that would comply with the notching level we have determined will provide
adequate protection.117 Further, to require that all of the amateur bands be notched would unnecessarily
restrict BPL operations in areas/locations where no amateur operations are present that could receive
interference.
46. As indicated above, we see no statistically-valid support for ARRL's position that the
ambient noise levels have become so low as to contradict our conclusion here that a 25-dB notch is
generally sufficient to protect licensed services.118 Further, for fixed stations, if a 25-dB notch is not
sufficient to resolve observed harmful interference or other steps to resolve the interference are not
successful, under Section 15.5(c) of the rules, the operator is then, upon notification by a representative of


114 ARRL November 2010 ex parte comments at Exhibit A at 14 and UTC ex parte comments (filed May 4, 2011) at
2.
115 ARRL November 2010 ex parte comments at para. 8 and Exhibit A.
116 See discussion in para.42, supra.
117 UTC ex parte comments (filed May 4, 2011) at 2.
118 We disagree with ARRL that the single measurement by our staff of a noise level below 0 dBV/m shows that
noise levels are typically below the ITU residential noise floor. One observation is not a sufficient sample to
statistically support any conclusion(s). See also, ARRL reply comments in which it agreed that the FCC Lab finding
is not sufficient justification [that the noise floor has decreased], and that the ITU-recommend noise floor levels are
indeed reasonable and typical and that even other competent bodies such as the North Atlantic Treaty Organization
(NATO) believe that these ITU noise floor numbers are still valid today. ARRL reply comments at 8 and its Exhibit
A at 7.
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the Commission, required to cease operation until the interference is corrected. In such cases, the
interference might perhaps be resolved by using new equipment that includes a filter with a notch
capability greater than 25 dB. We believe, however, that the new 25-dB notching requirement will be
sufficient to resolve the great majority of cases of harmful interference that might occur and therefore do
not see a need to require that Access BPL systems routinely use equipment with greater notching
capability.
47. In changing the notching level to 25 dB, we are aware that Access BPL operators have
already installed equipment with 20-dB notching capability in compliance with the rules and that there is
some inventory of equipment built to that standard which has not yet been installed. While we believe
that the greater level of protection provided by our rule change is prudent in the long term, we have not
observed any cases to date where the notching afforded by existing equipment has not been adequate to
resolve interference. Accordingly, given the limited number of devices already deployed and
manufactured, we will not require their replacement or prohibit their installation for replacement or in
new constructions. In order to afford manufacturers time to redesign their equipment to comply with the
new, more conservative 25-dB notching requirement, we will allow an 18-month period from the date this
action is published in the Federal Register before the requirement becomes effective.
48. In its reply comments, ARRL submits that IBEC did not resolve interference complaints to
amateur fixed stations by doing what the existing BPL rules require, other than compliance with the
general Part 15 requirement to correct any harmful interference.119 It states that instead, IBEC has
avoided or resolved the interference by doing two of the things that ARRL has requested as modifications
to the existing BPL rules: 1) IBEC avoided the use of Amateur bands in its installations, and 2) it has used
state-of-the-art notch depths of 35 dB. We observe that avoiding a frequency band where interference
could occur is certainly an option that is contemplated under the rules. Using a notching capability with
attenuation of greater than that required in the rules where needed is also consistent with the general
requirement in Part 15 rules that a device not cause harmful interference. We do not, however, find the
fact that equipment which can provide 35-dB notching capability is now available and IBEC's choice to
use such equipment to be indicative that we should require that level of notching capability in all
instances. Rather, while the rules will now require a notching capability of at least 25 dB, that level of
attenuation will only be deemed sufficient for resolving harmful interference in the case of mobile
operations; the system operator is still responsible for resolving harmful interference to fixed operations if
the 25-dB notch capability is used and the interference remains. Under the notching rules we are
adopting, a BPL system operator has the flexibility to install a notching capability greater than 25 dB or to
implement other measures for resolving harmful interference in cases where the 25-dB notch is not
sufficient. In this regard, IBEC did, in fact, take the steps required under Section 15.611(c) of the rules
it configured its systems to be capable of remotely reducing power by 35 dB and adjusting operating
frequencies to avoid site-specific, local use of the same frequencies by licensed radio operations.120 A
different operator might have chosen an alternative approach for complying with this rule.
2.

Preliminary Documents released in July 2009

49. In its comments, ARRL addresses the three additional staff PowerPoint presentations that
were placed into the record on July 22, 2009 (three additional presentations).121 It contends that these


119 Reply comments of ARRL at 3.
120 47 C.F.R. 15.611(c).
121 These presentations, as listed in Appendix F, are "Field Strength Measurements Relative to ARRL Concerns
Regarding BPL," October 16, 2003; "Broadband Over Power Line (BPL) Test Results and Considerations,"
December 3, 2003; and "BPL Emission Tests in Briarcliff Manor, NY," August 17-19, 2004.
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presentations are "most relevant" to the determination of the actual interference potential of BPL to
licensed radio services, the proper radiated emission level for BPL systems at HF, the proper distance
extrapolation factor for signal decay, and the necessity of full-time notching of all Amateur Radio
allocations by BPL systems in order to avoid interference.122 ARRL argues that, in the aggregate, these
presentations show that the Commission's assumptions in the BPL Order with respect to the interference
potential of BPL to the amateur service, both fixed and mobile stations, were wrong.123
50. ARRL first states that the three additional presentations collectively show that radiated noise
from overhead power lines carrying Access BPL signals increases significantly above the ambient noise
level when measured at ground level.124 It alleges that the BPL Order improperly focused on mitigating
interference to licensed services after the fact, rather than on preventing interference from BPL to licensed
services ex ante.125 ARRL contends that the Amateur Service is uniquely adversely affected by BPL
interference and that the probability of harmful interference to amateur communications is virtually 100
percent in residential areas where there are overhead MV power lines. ARRL asserts that practical
experience with BPL interference indicates that the information in the three staff presentations was
absolutely correct: interference is not practically resolved post hoc, and BPL has a far higher likelihood
of interference to the amateur service than other Part 15 devices, which are qualitatively different. It
demands that the rules be revised in view of these facts just now coming to light.126
51. Notwithstanding ARRL's contentions, we did consider the information in these
presentations in the BPL Order and in the formulation of our rules for regulating interference from Access
BPL emissions. There are no new facts, information, or interpretations in these presentations or in
ARRL's comments that are inconsistent with our previously stated understandings and findings. These
presentations, as well as other information in this proceeding, show that Access BPL operations can raise
the RF noise level to levels above the noise floor such that they can cause interference to amateur
operations in the close vicinity of power lines on which the BPL signals are carried. As the presentations
show, the area of interference is essentially limited to distances close to and along the power lines.127
While some interference is possible at locations close to the power line, we believe that in the great
majority of locations, interference will not occur to radio services because either propagation conditions
limit the range of the Access BPL emissions or there is no licensed amateur station present and operating
on the frequencies on which such emissions appear. We see no need to require an Access BPL operator
to reduce emissions below the Part 15 limits where there is no potential for interference. In addition, we
have required that a database of Access BPL systems be established to allow amateur operators to identify
BPL operations in their area before the systems commence operation so that they have an opportunity to
alert the BPL operator of their presence before the system is activated.128 We address specific points in
ARRL's arguments in the following paragraphs.
52. ARRL argues that the three additional presentations released in July 2009 show that in


122 ARRL comments at 39.
123 Id. at 45.
124 Id. at 46.
125 Id. at 45.
126 ARRL comments at p. 45-46.
127 See for example, "BPL Emission Tests in Briarcliff Manor, NY," slide 23 "distance away from the power line,
which exhibits a rapid drop-off with distance."
128 The requirements for the Access BPL database are set forth in Section 15.615(a) of the rules, 47 C.F.R.
15.615(a).
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recent years, the ambient noise levels have decreased below the rural noise levels recognized by the ITU
and that this reduction in the noise floor results in a greater potential for interference to amateur
communications.129 In particular, it observes that the first presentation, "Field Strength Measurements
Relative to ARRL Concerns Regarding BPL," indicates that, according to a December 2001 report by
NTIA (2001 NTIA Report), ambient noise levels measured at 137 MHz in the VHF band have decreased
by 10 dB since the ITU noise models were adopted.130 ARRL submits that this indicates that the actual
residential noise floor is now 4 dB below the ITU rural curve. It also points to a (single) measurement by
the staff at the FCC Laboratory of noise levels in the MF and HF bands used by the amateurs that showed
the ambient noise to be 5-8 dB below the ITU rural curve.131 It points to slides 11 and 12 of the above
presentation and argues that with this reduction in the noise floor, BPL emissions can now be the source
of a 25-35 dB increase from the noise floor at 30 meters from the power lines and that this will have a
major impact on some amateurs.
53. IBEC states that to provide another data point on background noise levels, it made
observations of the background noise level over the frequency range 2-30 MHz at two locations chosen at
random, one residential and the other business.132 IBEC's quasi-peak measurements at these locations
show business noise levels 10 dB higher and residential noise levels 20 dB higher than the ITU levels.
IBEC does, however, also acknowledge that further investigation is needed to describe the noise
environment today.133
54. The presentations and measurements mentioned in the comments and in the three additional
presentations do not provide a basis for any general conclusions regarding changes in the noise floor.134
The study in the 2001 NTIA Report only looked at VHF frequencies 137 MHz and above and this report is
therefore not directly relevant to the noise levels on the medium frequencies (MF) or HF frequencies
30 MHz and below that are at issue here.135 We therefore continue to believe that our reliance on the
current noise levels recognized by the ITU is appropriate and that in this regard, the potential for
interference from BPL emissions remains the same as we considered in the BPL Order. We acknowledge
that a compliant BPL system will increase the noise floor within a relatively short distance of the power
lines (typically ranging from less than 15 meters to 400 meters, depending on frequency, type of receive


129 A lower noise floor would allow amateurs to receive signals at lower levels.
130 ARRL comments at 39; see also NTIA Report No. 02-0390, "Man-Made Noise Power Measurements at VHF
and UHF Frequencies," Robert J. Achatz and Roger A. Dalke, December 2001 (2001 NTIA Report) at 33; see also
"Field Strength Measurements Relative to ARRL Concerns Regarding BPL" at slide 6.
131 ARRL also notes that the noise measurements were made at a representative height for amateur radio antennas
(10 meters high and 30 meters from the antenna).
132 IBEC comments at 4-5.
133 In its reply comments, ARRL argues that IBEC's measurements of the noise floor are flawed, because it appears
that IBEC was measuring the noise level of its EMC instrumentation, not the actual noise floor. ARRL reply
comments at 6-7.
134 We further note that ARRL argued at length in its comments that the Commission had proof [from the result on
these slides] that the noise floor has decreased and thus the amateur service would be subject to higher levels of
interference in this lower noise floor environment. ARRL comments at p. 42. However, in its reply comments filed
subsequently, ARRL agreed that the FCC Lab finding is not sufficient justification [that the noise floor has
decreased], and that the ITU-recommend noise floor levels are indeed reasonable and typical and that even other
competent bodies such as the North Atlantic Treaty Organization (NATO) believe that these ITU noise floor
numbers are still valid today. ARRL reply comments at 8 and its Exhibit A at 7.
135 The medium frequency (MF) region covers frequencies from 300 kHz to 3 MHz.
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station and location-specific behavior of the BPL operation), and have determined that this increase is
acceptable so long as the system's operation does not cause harmful interference.136 Under the rules, the
Access BPL operator is required to take steps, including using frequency notching or band avoidance as
necessary (which amounts to shutting down operations in the affected band), to avoid any such harmful
interference that might occur, and/or resolve it if it does occur.
55. ARRL next observes that slide 3 of the "Broadband Over Power Line (BPL) Test Results
and Considerations" presentation contains statements that "resolving interference complaints will be
difficult/impractical;" and that Part 15 radiated limits were "[a]dequate for most devices, but not for
BPL."137 ARRL states that the difference, as noted in the presentation, is that BPL has a broad
bandwidth; it has high emissions over that wide bandwidth; it is exempt from conducted limits except in
the AM broadcast band; it is in close proximity to neighboring residential antennas, including those used
to receive amateur signals; there are no intervening walls to attenuate interference; and the radiators have
a large spatial extent. It submits that these differences were each noted by ARRL in its comments in this
proceeding before the BPL Order, but that the Commission claimed it believed otherwise. Contrary to
ARRL's claim, we did, indeed, recognize all those factors (and others) and considered them in
formulating our requirements for Access BPL systems that are in addition to those applied to carrier
current systems.138 We are, and were, aware that amateur receive sites are typically located outdoors in
relatively close proximity to power lines and that BPL emissions are likely to be present over all or large
portions of the amateur bands. These considerations, as well as similar considerations with respect to
other services, led us to require that Access BPL operators be capable of remotely managing their
facilities to reduce or eliminate emissions in locations where interference might occur and to require
establishment of a database of BPL operations so that licensed radio users could contact the local BPL
operator if interference were to occur. We also disagree that resolving complaints from BPL systems is
particularly difficult or impractical, in that BPL emissions often create a very distinctive audio tone or
pattern of broadband noise burst that is easily recognized and interference from a BPL system can be
conclusively identified by simply having the system cease operation for a brief period of time on the
affected frequencies.139


136 The amount of increase in the noise floor diminishes rapidly with distance from the power lines, but depends on
a number of other factors as well. The impact of an increase in the noise floor will be greatest for sensitive receivers
with antennas located well above the ground in locations with low ambient noise. Noise increases would be smaller
if the receiver operates at a frequency at which the local BPL emissions are significantly below the emission limit or
if ambient noise levels are higher -- as might be expected in a business environment or where higher levels of RF
noise are present from other sources. Noise increases would be larger if the receiver operates in a region with
ambient noise levels typical of rural or quiet rural areas. We note generally that the consensus in the technical
community is that the noise floor has been steadily increasing due to the ever growing proliferation of electronic and
electrical equipment that are all capable of generating man-made radio noise. See for example, Radiated and
Conducted EMI Emissions in Switch Mode Power Supplies (SMPS): Sources, Causes and Predictions
, by Nagrial,
M.H. and Hellany, A. IEEE INMIC 2001, Technology for the 21st Century Proceedings IEEE International, p. 54-
61, at http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=995314; and Indoor Noise Conditions in the FM
Broadcast Band
, by Johnston, S. National Association of Broadcasters (NAB) Engineering Conference 2010 at
http://m.core-apps.com/2010NAB/events/51f39223ab6d2bfd89cd88a156bd8b9b.
137 ARRL comments at 41.
138 BPL Order at 21275-21276.
139 We also note that non-OFDM BPL systems and some OFDM BPL systems have been observed to sound like
pulsed broadband noise, which may not be aurally distinctive from the surrounding white noise. However, a system
using a noise-like modulation method would appear to create noise-like common power line emissions and could be
readily evaluated as a possible source of any interference by briefly switching the signal off or activating the
system's notching capability on the frequencies on which the interference was occurring.
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56. ARRL raises issues with regard to the presentation "BPL Emission Tests in Briarcliff
Manor, NY," arguing that the notches on amateur radio bands in that system were inadequate and that in
one case a notched BPL device was filled in by noise from another device operating 0.7 miles away. It
further observes that, as shown on slides 19 and 22 of that presentation, BPL audibility in a mobile
receiver quickly ends when roads depart from the power lines but could be heard along the lines up to
1.7 miles from the nearest in-band BPL device.140 ARRL argues that this information shows that
localized notching of the amateur bands is not effective in resolving interference. However, it is quite
plain from other information on slide 13 of this presentation that the notching feature implemented in the
early models of BPL equipment used in the Briarcliff Manor experiment were not functioning properly.
We therefore do not consider this information to be a representative example of the performance potential
of the notching capabilities of BPL systems. Our staff has also made other observations of notched BPL
signals, for example at the Manassas, VA system, where notching capability as required under the rules
was implemented and was very successful in eliminating interference.141
57. We also note that throughout this proceeding and as new equipment that allows BPL
operators to better manage their frequency use at specific locations has become available, we have
observed BPL operators taking active steps to locate and avoid interference to amateur operators.142
Given that identification and resolution of harmful interference can involve expenditures of staff time and
resources for Access BPL providers and possibly the temporary disruption of service to their subscribers,
these providers have a strong incentive to take a priori steps to ensure that they avoid causing interference
to the local radio services, including amateurs. Notwithstanding the occasional interference that was
found by amateurs from the trial systems that were operated during the early phases of BPL development
such as those examined in the staff presentations (and which, in some cases, were operating with
emissions levels that were found to exceed the Part 15 limits by amounts ranging from 1 to 4 dB), we
have observed, as described by IBEC and CURRENT in their comments, that Access BPL operators are
taking effective steps as contemplated in the BPL Order to avoid interference to amateur and other
licensed services, including working with local amateur operators.143 Moreover, our own internal records
on enforcement matters show only one complaint of interference from Access BPL to fixed licensed
operations; that complaint was submitted recently and is under investigation at this time.144 In summary,
we therefore see no new information or reasoning in ARRL's submissions or other information regarding
the three additional staff presentations in the preliminary materials released in July 2009 that would
warrant changing the current rules and, specifically, we see no need to further restrict the operations of


140 ARRL comments at 45.
141 See Letter dated March 2, 2007 from the Commission's Enforcement Bureau to various parties, including Chris
Imlay, General Counsel of ARRL.
142 For example, ARRL reports that BPL manufacturers have [voluntarily] implemented notching of the amateur
bands in all of the installed systems. It further indicates that ARRL technical staff has evaluated five different
installations using second-generation BPL equipment with 35-dB notch depth applied to the amateur bands and
found this to be a successful model to prevent interference problems. ARRL comments at 10, footnote 9. We view
these efforts by the BPL industry as an important demonstration of their willingness and commitment to cooperate in
avoiding interference to the amateur service under the flexible rules adopted in the BPL Order.
143 CURRENT comments at 2-3.
144 See Re: Interference Complaint: IBEC Access Broadband Over Power Line Systems from ARRL to Kathryn
Berthot, Chief, FCC Spectrum Enforcement Division, and Julius Knapp, Chief, FCC Office of Engineering and
Technology (filed Dec 29, 2010). The BPL system database (http://www.bpldatabase.org/), which is operated
jointly by the United Power Line Council and the Utilities Telecom Council pursuant to the requirement in Section
15.615(a) of the rules (47 C.F.R. 15.615(a) shows that BPL systems are currently operating in more than 125 zip
codes across the United States.
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BPL systems to protect licensed services.

B.

Measurement Distance Extrapolation Issues

1.

The Extrapolation Factor

58. Overview. In the BPL Order, the Commission set forth guidelines for measurement of
the emissions from Access BPL systems.145 These guidelines, inter alia, specify that emissions from
Access BPL devices operating below 30 MHz are to be measured for compliance with the radiated
emissions limits in Section 15.209 of the rules.146 Those limits are based on measurements made at
30-meters horizontal (lateral) distance from the device under test.147 However, for practical reasons
associated with measurement in the field, the Access BPL measurement guidelines recommend that
measurements should normally be performed at a horizontal separation distance of 10 meters from the
overhead power line, and they also indicate that measurements can be performed at 3 meters if
necessary because of ambient emissions, safety or practical considerations.148 The field strength of
radiated emissions does, however, decrease with increasing distance from the emitter due to
propagation loss. Because of this attenuation with distance, the field strength of emissions from a
device measured at the 3-meter or 10-meter distances specified in the guidelines will generally be
higher than those measured at the 30-meter distance on which the emission standard is based. In
order to apply the emissions standard consistently, the measurement results must be adjusted to
account for distance attenuation when measurements are made at a distance other than 30 meters.
59. The Commission specified distance extrapolation factors to convert the BPL emissions
measurements for frequencies below and above 30 MHz to appropriate values for tests made at the
3-meter and 10-meter distances recommended in the BPL measurement guidelines. For BPL
operations on frequencies below 30 MHz, the frequency range at issue here, some commenters in the
initial phase of this proceeding, including ARRL, recommended the use of an extrapolation factor of
20 dB/decade, while others recommended an extrapolation factor of 40 dB/decade.149 The
Commission concluded in the BPL Order that "[g]iven the lack of conclusive experimental data
pending large scale Access BPL deployments," it would "continue the use of the existing Part 15
distance extrapolation factors" specified in the rules, i.e., 40 dB/decade for frequencies below 30
MHz and 20 dB/decade for frequencies at or above 30 MHz, but with the distance measured as the
slant-range distance from the overhead power line to the center of the measurement antenna rather
than horizontal (lateral) distance from the nearest point of the overhead power line carrying the BPL
signals to the center of the measurement antenna, as illustrated in Figure 1 of Appendix C, infra. This
is the horizontal (lateral) distance between the center of the measurement antenna and the vertical
projection of the overhead power line carrying the BPL signals down to the height of the
measurement antenna when measurements are taken at a point that is perpendicular to the power
lines.150 It further stated that "if new information became available that alternative emission


145 See Guidelines in Appendix C of the BPL Order, at 21339-21343.
146 See 47 C.F.R. 15.611 and 47 C.F.R. 15.209.
147 See 47 C.F.R. 15.31(f).
148 The common concurrence of power lines and roadways means that the specified distance to conduct
measurements will often occur in those roadways on obviously unsafe places, or inside privately-owned properties.
149 BPL Order at 21310.
150 Id. The slant-range distance is the diagonal distance from the center of the measurement loop antenna, which is to
be at 1 meter above ground level, to the overhead power line to which the BPL device is coupled, typically several
meters above ground. The slant-range method reflects the actual measurement distance from the measurement
antenna to the BPL-carrying power line whereas the horizontal distance method used with other Part 15 devices in
(continued....)
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limit/distance standards or extrapolation factors would be more appropriate," it would revisit this
issue at another time.151
60. ARRL filed a petition for reconsideration of the Commission's decision in the BPL
Order to use 40 dB/decade as the extrapolation factor for frequencies below 30 MHz.152 In support of
its argument that an extrapolation factor of 20 dB/decade should be used, ARRL also submitted,
through ex parte comments, reports on three studies conducted by the United Kingdom's Office of
Communications (OFCOM) and a standard by the Special International Committee on Radio
Interference (CISPR) regarding emission measurements for BPL systems and a proposal for a sliding
scale extrapolation factor based on a 1996 CISPR standard.153 The first OFCOM study, "OFCOM,
Ascom PLT Measurements in Winchester (May 11, 2005)
" (Winchester Study) reported
measurements of an underground Access BPL trial system in Winchester, United Kingdom.154 In that
study, OFCOM concluded that the electromagnetic field attenuates at a rate between 20 dB and
25 dB/decade at this BPL installation. The second OFCOM study, "OFCOM, DS2 PLT
Measurements in Crieff (May 11, 2005)
" (Crieff DS2 Study) reported measurements of an Access
BPL trial system in Crieff, United Kingdom. That study concentrated only on the benefits of
programmable notches in the equipment and did not provide any data on distance extrapolation.155
The third OFCOM study, "OFCOM, Amperion PLT Measurements in Crieff (May 11, 2005)" (Crieff
Amperion Study) reported measurements of an overhead, pole-mounted Access BPL trial system,
also in Crieff, United Kingdom.156 In the Crieff Amperion Study, OFCOM concluded that the
emitted field attenuates at a rate of 28 dB/decade.
61. Subsequent to the filing of the report on the Crieff Amperion Study into the record of
(Continued from previous page)


this case is less than the actual distance to the emitter. See illustration of slant-range distance in Appendix C, infra.
For example, if the measurement antenna is located 10 meters horizontal distance from the nearest point directly
under the overhead power line carrying the BPL signal, at a height of 1 meter, and the power line is 11 meters above
the ground, the slant range distance from the antenna to the power line is 14.14 meters. As such, because the slant
range distance is longer than the horizontal distance to the nearest point directly under the overhead power line
carrying the BPL signal (in this example, approximately 140% of the horizontal distance), the permissible emission
levels at the measurement distance are reduced when this method is used. Therefore, even though we apply the
general emission limits in Part 15 to Access BPL devices, these devices are not allowed to emit as much as other
Part 15 devices that must be measured in situ and that radiate primarily from a height much greater than 1 meter, due
to the application of slant-range distance to calculate the extrapolated emission level. This is another example of the
more conservative regulation placed on Access BPL devices as part of the BPL framework the Commission adopted
in 2004.
151 BPL Order at 21310.
152 See ARRL Petition for Reconsideration (filed Feb. 7, 2005 in ET Docket 04-37); see also, ARRL Petition for
Issuance of Further Notice of Proposed Rule Making and for Amendments of Regulations (filed Oct. 18, 2005) in
ET Docket No. 04-37.
153 See ARRL ex parte Citation of Additional Authority comments (ARRL ex parte comments), filed July 8, 2005 in
ET Docket 04-37, at http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6518006426.
154 OFCOM, Ascom PLT Measurements in Winchester (May 11, 2005) at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6518006428. Note that the FCC
recommends making measurements no closer than 10 meters from the power line for safety reasons.
155 OFCOM, DS2 PLT Measurements in Crieff (May 11, 2005) at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6518006429.
156 OFCOM, Amperion PLT Measurements in Crieff (May 11, 2005) at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6518006427.
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this proceeding, Amperion submitted comments stating that this report "reflects information that is
inappropriate for the public domain, especially the way it is inaccurately represented."157 Amperion
argued that there are "discrepancies in the report," which it attributes to "[OFCOM's] unfamiliarity
with the equipment and the hurried nature in which the testing was conducted." These discrepancies
include that 1) OFCOM operated the BPL equipment at its maximum power levels, which was above
the much lower level used for normal operations, without explaining that in the report, and 2) the
system was not configured to comply with the Commission's limits.158
62. ARRL's proposal for a sliding scale extrapolation factor referenced a 1996 CISPR
Standard.159 That standard, which was published in 1996 well before Access BPL was developed,
evaluates radio noise generated by high-voltage converter power stations and similar high-voltage
installations and discusses methods on how to reduce radio noise from inherent power line
components, such as mercury arc and thyristor valves. ARRL pointed to a graph in the standard
which shows calculated values of the field strength attenuation of emissions from a vertical electrical
dipole antenna as a function of the distance on a horizontal plane for different frequencies.160 Based
on this graph, ARRL proposed a formula which effectively constitutes a sliding-scale calculation for
an extrapolation factor that varies with frequencies.161
63. On reconsideration, the Commission found the OFCOM studies and the CISPR standard
unpersuasive in that there was no "new" or convincing information not already known, and affirmed
its decision to use the existing Part 15 distance extrapolation factor of 40 dB/decade attenuation rate
in the measurements of BPL emissions on frequencies below 30 MHz.162
64. In ARRL v. FCC, supra, the court found that the Commission did not offer a reasoned
explanation for its dismissal of empirical data that was submitted ex parte by ARRL, i.e., the three
OFCOM studies and additional ARRL analysis intended to suggest that an extrapolation factor of
20 dB/decade may be more appropriate for Access BPL.163 The court ordered the Commission either
to "provide a reasoned justification for retaining an extrapolation factor of 40 dB/decade for Access
BPL systems sufficient to indicate that it has grappled with the 2005 studies, or adopt another factor
and provide a reasoned explanation for it."164
65. The Commission acted to respond to the court's directive in the RFC/FNPRM. Therein,


157 See Amperion comments (filed May 20, 2005 in ET Docket 04-37) at
http://fccweb01w/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6517611850, at 2-3.
158 We note that operating the BPL equipment at maximum or typical power levels does not affect the determination
of the attenuation characteristics of the signal.
159 Radio Interference Characteristics of Overhead Power Lines and High-Voltage Equipment Part 2: Methods of
Measurement and Procedure for Determining Limits,
CISPR 18-2, Amendment 2, (1996), (CISPR 18-2) at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6518006430.
160 ARRL ex parte comments at 6. See also, CISPR 18-2 at 20.
161 The formula ARRL recommended to the Commission to calculate extrapolation is as follows: Distance at 30
meters = distance at slant range 20 log (30/slant range) 20 log (15/frequency in Megahertz). ARRL ex parte
comments at 6.
162 See BPL Reconsideration Order at 9318.
163 ARRL v. FCC at 241.
164 Id., at 242. The court did not separately address ARRL's contention that the Commission failed to consider a
sliding scale extrapolation factor, assuming that it was properly before the Commission on reconsideration. Id.
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it provided a more detailed explanation of its reasons for selecting 40 dB/decade as the extrapolation
factor for frequencies below 30 MHz and in particular why it does not believe that the studies and
technical proposal submitted earlier by ARRL provide convincing information that it should use an
extrapolation factor that is different from (and, specifically, less than) 40 dB/decade as required in the
second element of the court's directive in ARRL v. FCC.165 In summary of that explanation, the
Commission stated that:
1) There were no significant studies that examined the very large number of measurements
that would be needed to address the different site characteristics that affect the attenuation of
emissions below 30 MHz;
2) The studies submitted by ARRL in its 2005 ex parte provided only anecdotal information
on two different types of installations (overhead and underground) from two single sites and
also had certain methodological shortcomings; and
3) With respect to its proposal for a sliding scale extrapolation factor, ARRL did not provide
an explanation as to how its formula was derived or how to use it to determine the
extrapolation factor, nor did it provide a rationale for selecting such a formula or information
as to the relationship between the performance of emissions from BPL technology and the
specifications for reduction of power line noise adopted in the standard.
66. In the RFC/FNPRM, the Commission also observed that since its adoption of the BPL
Reconsideration Order, reports had become available on two new technical studies addressing
attenuation of BPL emissions with distance, one by NTIA in October 2007 that described a second
phase of its simulation study on the potential for interference from Access BPL systems (NTIA Phase
2 Study
) and the other by the Federal Republic of Brazil (Brazil Study) in June 2008 that presented the
results of a measurement study of BPL emissions.166 In addition, it noted that the IEEE working
group on power line communications technology electromagnetic compatibility was working on a
standard for EMC testing and measurements methodology for BPL equipment and installations (IEEE
P1775/D2) that included a provision for determining extrapolation (distance correction) factors on a
site-by-site basis using in situ measurements as part of its work on that standard.167
67. In view of these new studies and consistent with its stated intention in the BPL Order to
revisit the extrapolation factor if new information became available and the opportunity provided by
the Court's remand of the extrapolation factor, the Commission decided to conduct further


165 See RFC/FNPRM at 9679-9680. The Commission's explanation of its consideration of the OFCOM reports in
the RFC/FNPRM responded to the court's directive that the Commission explain that it had "grappled with the
empirical data" in those reports. That explanation describes the rationale underlying its succinct conclusion in the
Reconsideration Order that those reports provided no new information that would provide a convincing argument
for modifying the extrapolation factor. BPL Reconsideration Order at 9317-18. In paragraphs 71-91 below, we
revisit our decision on the extrapolation factor. We maintain our finding that 40dB/decade is the appropriate value
for this distance adjustment and provide additional analysis and rationale for our decision and address the arguments
of the amateurs for selection of a more conservative value.
166 See RFC/FNPRM at 9680-9681; see also Potential Interference From Broadband Over Power Line (BPL)
Systems to Federal Government Radiocommunications at 1.7 80 MHz, Phase 2 Study
, Volume I, National
Telecommunications and Information Administration (NTIA) Report 08-450, October 2007 ("NTIA Phase 2
Study"
), at http://www.ntia.doc.gov/osmhome/reports/2007/bpl2007.html; and Federal Republic of Brazil, Radio
Interference Tests from Broadband Power Line Communication Systems
, ITU Radio Communication Group WP-
1A, Document 1A-32-E, June 9, 2008 ("Brazil Study") at
http://fjallfoss.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6520190420. Both of these studies
have been added to the record of this proceeding.
167 IEEE 1775-2010 was published on Jan 7, 2011. See para. 11 and footnote 40, supra.
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rulemaking to review its decision on the extrapolation factor.168 It requested that interested parties
submit additional comment and information on the BPL extrapolation factor and specifically asked
that such comment and information address 1) the three studies and proposal for a sliding scale
extrapolation factor submitted previously by ARRL as part of its ex parte filing of July 8, 2005 in this
proceeding, 2) the NTIA Phase 2 and Brazil studies with respect to their findings on the extrapolation
factor for BPL systems, and (3) the existing slant-range method as it pertains to the effective field
attenuation rate in a horizontal distance context. The Commission further requested submission of
any other new empirical studies or information that may provide information regarding the BPL
distance attenuation extrapolation factor. The Commission stated that its goal in this review is to
provide BPL measurement procedures that will adequately ensure compliance with the Section
15.209 emissions standard for emissions at or below 30 MHz without placing unfair or undue
compliance burdens on equipment manufacturers and users. In conducting this review, the
Commission indicated that initially it continued to believe the existing 40 dB/decade extrapolation
factor, in conjunction with the slant-range distance method, was reasonable and appropriate for
adjusting measurements of BPL emissions on frequencies below 30 MHz.
68. As discussed above, the Commission also recognized that there is considerable
variability around the 40 dB/decade value at different sites. The result of this variability is that the
actual attenuation at some sites could be less than 40 dB/decade and using the current extrapolation
factor at such sites could produce an adjusted measurement that would be less than the level that
would be measured at the standard 30-meter measurement distance specified in Section 15.209. The
Commission therefore requested comment on whether it would be desirable to modify the value of the
BPL extrapolation factor to be 30 dB/decade or some other value.169 It observed that extrapolated
emission levels based on a 30 dB/decade extrapolation factor when applied to slant distance would be
comparable to the extrapolated emission levels based on a 20 dB/decade extrapolation factor applied
to horizontal (lateral) distance.170 Recognizing that reliance on a 30 dB/decade extrapolation factor
could increase the compliance burden for BPL equipment and systems that are tested at locations
where the attenuation rate is in fact in the range of 40 dB/decade or greater, the Commission clarified
that in all cases, measurements of Access BPL equipment and systems will be allowed to be made at
the 30-meters distance specified in Section 15.209 and that where possible, the Commission's staff
will make measurements at this distance when testing for compliance.171
69. In its comments, ARRL argues that the Commission's "attempt in the Further Notice to
justify the 40 dB/decade extrapolation factor adopted in the Access BPL Order and affirmed in the
[BPL] Reconsideration Order is insufficient."172 It contends that the explanation provided in the
RFC/FNPRM relies on calculations premised on flawed scientific methodology and disregards
empirical measurements. Representatives of the Access BPL industry support maintaining the
40 dB/decade standard. In this regard, Ambient states that the continued use of the 40 dB/decade
distance provides the most accurate extrapolation value, within a round-off resolution of 5 dB/decade,


168 RFC/FNPRM at 9680-9681.
169 Id. at 9679, 9682-9683.
170 This is true for measurement distances greater than 12 meters laterally from the pole. At measurement distances
less than 12 meters, the extrapolated emission levels based on the proposed 30 dB factor applied to slant distance are
much more stringent than extrapolated levels based on a 20 dB factor applied to horizontal distance. See Figure 3 in
Appendix D of the RFC/FNPRM at 9693.
171 See RFC/FNPRM at 9682-9683.
172 ARRL comments at 17-18. Individual amateur radio operators submitting comments indicate that they support
ARRL's position on these matters.
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for compliance measurements in typical overhead BPL geometries.173 Arkados Group, Inc.
(Arkados), the HomePlug Powerline Alliance (HomePlug) and Intellon Corporation (Intellon) argue
that prompt case-by-case resolution of any actual interference complaints is the preferable solution to
the issues underlying ARRL's objections, rather than adopting an "overly exclusive" new rule that
could stunt the growth of new innovative technologies that hold great promise for broadband and
smart grid applications.174 IBEC submits that it has not experienced any issues with licensed services
that could not be addressed within the framework of the existing BPL rules.175
70. ARRL and several representatives of the Access BPL industry oppose our proposal to
modify the extrapolation factor to be 30 dB/decade, albeit it for differing reasons.176 While ARRL
contends that a 30 dB/decade factor would be too lenient, Arkados and HomePlug contend that making
the regulatory environment even more restrictive without strong justification would have severe
implications for the government's initiative to provide cleaner and greener energy.177 SPiDCOM
Technologies, S.A. (SPiDCOM) submits that a reduced extrapolation factor would directly reduce the
performance of all BPL devices such that it would be difficult if not impossible to provide a marketable
product for Access BPL, SmartGrid BPL and In-home BPL markets.178 No new empirical studies of the
attenuation rate of emissions from power lines on frequencies below 30 MHz were submitted into the
record of this proceeding.179
71. Discussion. After consideration of the most recent information and comments on this matter
and further deliberation on all of the studies and information in the record, as described above, we are
retaining the 40 dB/decade extrapolation factor for frequencies below 30 MHz. As discussed further
below, there are several reasons that lead us to this conclusion. Initially, we observe that the 40
dB/decade extrapolation for frequencies below 30 MHz has served successfully in our program to control
emissions from radio frequency devices for many years. We also observe that, while ARRL contends that
20 dB is the only scientifically correct and valid value for an extrapolation factor, the studies and
information before us show considerable differences in extrapolation factors under various powerline
system configurations and usage conditions. We conclude that there is no single "correct" value for an
extrapolation for RF emissions from power lines, and instead find that the compelling and reasonable


173 Ambient reply comments at 1. Ambient also submits 416 pages of simulation data showing that the extrapolation
factor varies from 34 to 47 dB/decade for frequencies from 5 to 30 MHz. Id. at 4.
174 Arkados reply comments at 2, HomePlug reply comments at 2; Intellon reply comments at 2.
175 IBEC comments at 2.
176 SPiDCOM comments at 2, UPLC comments at 6.
177 Arkados comments at 2, HomePlug comments at 3.
178 SPidCOM comments at 2.
179 On Jan 11, 2010, ARRL submitted in ex parte a draft field test report by the Communications Research Centre,
Canada that describes measurements of radiated emissions from In-House BPL devices: Measurements of EM
Radiation from In-House Power Line Telecommunications (PLT) Devices Operating in a Residential Environment,
Communications Research Centre, Canada, Field Test Report, Draft 2.3, March 24, 2009. The draft indicates that
this report was conducted to determine the extent of potential interference of these devices to broadcast services
operating in residential environments. The report noted that the study found an average of 18.2 dB/decade
attenuation rate from the side of the house to locations outside the house for the In-House BPL devices tested.
However, the report does not present a theoretical discussion or other analysis of the physical properties of the
electrical wiring and its layout in the homes tested that would be expected to produce this result. Inasmuch as this
draft report describes measurements of emissions from In-house BPL systems, it is not relevant to the discussion of
Access BPL systems due to the physical differences in the operating configurations of the two types of systems.
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solution is to use the existing Part 15 extrapolation factor that both has a scientific basis and has stood the
test of time for a wide variety of devices and systems. We also note that, as discussed below, using the
slant range method in performing measurements has the effect of reducing the extrapolation factor to
approximately 20 dB. We consider too, that the extrapolation factor used with BPL measurements is only
one element in a comprehensive set of rules that are designed and intended to minimize the risk of
harmful interference from BPL operations and to put in place appropriate measures to eliminate such
interference if it should occur. In that context, the rules require that harmful interference be corrected
under any circumstances. Measurements for examination of compliance are important, to be sure, but
interference must be corrected even if measurements indicate that the BPL operations at the site are
compliant. While ARRL asserts that an extrapolation factor that is too lax will lead to widespread
instances of harmful interference that should be corrected ex ante as opposed to ex post, we have seen
little evidence of harmful interference being caused under the rules as adopted with a 40-dB extrapolation
factor.
72. In addition, we note that there is no support from any of the commenting parties that
modifying the extrapolation factor to 30 dB/decade in order to take a more conservative approach that
would compensate for the variability in the attenuation rate would provide a more appropriate
extrapolation factor. We therefore are not adopting that change. To provide clarity for those conducting
measurements for compliance of Access BPL equipment and systems with the Section 15.209 emissions
standards, we are specifying the extrapolated values of compliant emissions levels at 3-meter and
10-meter horizontal (lateral) distance from the nearest point of the overhead power line carrying the BPL
signals for typical heights of medium voltage power lines in the BPL measurement guidelines.180 We are
also adopting our proposal for a new method for determination of site specific extrapolation factors in
measurements of emissions from BPL systems.
73. Looking more closely at this issue, we find that ARRL has not provided convincing
information that the value of the measurement distance extrapolation factor for Access BPL should be
reduced from 40 dB/decade to 20 dB/decade or some other number close to that value. While ARRL
offers detailed and lengthy submissions of information on propagation of RF energy below 30 MHz and
critiques of the studies, analyses and information provided by others, including this Commission, that
information does not provide any new insights on radio propagation that would alter our decision.
Moreover, its arguments for a 40 dB/decade standard do not account for two key factors that affect the
significant attenuation of RF energy in this region of the spectrum: factors in the emissions process (such
as ground effects and the presence of multiple power lines and their position on the pole) and the
significant variability in attenuation rate across different installation sites.181
74. With regard to the OFCOM studies, ARRL maintains that if a single extrapolation number is
to be specified in the Commission's rules, the OFCOM Winchester Study establishes that extrapolation
should be 20 dB/decade in the spectrum region from 10 to 30 meters. However, ARRL concedes that at
lower frequencies, the extrapolation factor could be specified at a higher level, if the Commission wishes
to use a frequency/distance based formula.182 CURRENT argues on the other hand that "Figure 19 of the
OFCOM Winchester report shows that over the frequencies of 1.5 to 9 MHz, the extrapolation is
consistently greater than 30 dB/decade" and "the data at 3 and 10 meters show an extrapolation rate closer
to 35-40 dB/decade." CURRENT also contends that "[a]ll of these data are suspect [because] the


180 The revised measurement guidelines are set forth in Appendix D below.
181 The ARRL's presentation of its modeling of a 1000-meter line emitter does show results for emissions at 1 meter
height, and those results show that losses from the ground do increase the decay rate, see ARRL comments,
Appendix C at 15.
182 ARRL reply comments at 19.
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researchers conducting the study used a BPL-equipped substation adjacent to an open tract, and took their
measurements in the open space; [further], a close look at the published map shows a low-voltage line
running exactly parallel to the measurement path; that line appears to be carrying BPL signals and could
well have contaminated the measurements of emissions from the power line that was the subject of the
test."183 It further submits that none of the studies that ostensibly bear on the extrapolation question, i.e.,
OFCOM Winchester, OFCOM Crieff, Brazil Study, NTIA Phase 2 Study, and CISPR 18 unambiguously
point to a specific value that the Commission could adopt. As we discussed in the RFC/FNPRM, the
OFCOM Winchester study at best provides only anecdotal information that, not withstanding its
methodological shortcomings, is not sufficient to describe the very large number of measurements that
would be needed to address the general case in which different site characteristics significantly affect the
attenuation of emissions below 30 MHz.
75. ARRL next argues that during the period in which the Commission adopted and affirmed the
40 dB/decade standard, the Commission had evidence that 40 dB/decade is not the correct extrapolation
factor. In this regard, ARRL points to slide #19 of the Briarcliff Manor presentation which
"recommended" that the Commission should, if it intended to permit BPL on overhead MV power lines,
adopt a height correction factor and a "20 log R extrapolation factor."184 It contends that there is no
reference to this "FCC-Laboratory" recommendation" anywhere in the RFC/FNPRM, or heretofore by the
Commission whatsoever. ARRL also asserts that "instead, the Commission attempts in the RFC/FNPRM
to justify its decision for retaining the 40 dB/decade factor by citing studies that were not even in
existence at the time of the BPL Reconsideration Order."185 We find these arguments to be unpersuasive.
First, it is important to recognize that there is no "FCC-laboratory recommendation" as characterized by
ARRL. The Commission is under no obligation to discuss in a rulemaking proceeding every staff
observation or opinion provided during the course of internal deliberations. We observe that the 20
dB/decade extrapolation factor was part of one of three options presented on slide #19. The presentation
offered no specific analysis or measurement data supporting this extrapolation factor. Rather, as specified
on the slide, the authors offered it as a way to postpone and/or reduce the interference potential of BPL
systems. Additionally, as noted by Arkados and HomePlug, none of the five FCC staff presentations
actually examined the path loss extrapolation factor, but rather, they examined other technical issues such
as the effect of the distance down the power line, differences in radiated field strength due to the detector
that was employed, effect of measurement receiver antenna height, audible interference and antenna
polarization.186 We therefore did not, (and still do not) consider that the information on which the
provided option on slide #19 was based to be sufficient or compelling such that it should override or
supersede other information that we also considered in the extrapolation factor decision. As UTC


183 CURRENT comments at 6. Because OFCOM made its measurements for the purpose of showing the distance
attenuation of BPL signals of the particular BPL signal source under test away from the power line carrying that
BPL emitter, if there are other power lines also carrying BPL signals nearby, the test data may not be valid as the
measurements may have been made at a point closer to, or overlapping with, another BPL signal source.
184 See Briarcliff Manor presentation at slide #19.
185 ARRL comments at 48.
186 Arkados comments at 4; HomePlug comments at 4. Arkados, HomePlug and Intellon report that a recent study
by the Communications Research Center, Canada, found that the path loss coefficient to be 36 dB per decade at 37.8
MHz, with a shadowing standard deviation of 3.39 dB. Arkados comments at 8; HomePlug comments at 8; Intellon
comments at 7. The study they reference is: Jeffrey A. Pugh , Robert J. C. Bultitude and Philip J. Vigeron, Path
Loss Measurements With Low Antennas For Segmented Wideband Communications at VHF
, October 23-25, 2006,
Communications Research Center, Ottawa, available at
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4086379. Inasmuch as this study measures propagation at
37.8 MHz, which is above the MF and HF bands, it findings are not relevant to our decision on an extrapolation
factor for frequencies below 30 MHz.
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observes, the staff presentations merely included a 20 dB/decade extrapolation factor as one option
among many for regulating BPL operations in the HF bands; the presentations did not find that a 20-dB
extrapolation factor represented the actual rate of decay, nor did they contain any underlying information
or analysis that would support such a finding.187 Further, with respect to ARRL's assertions regarding our
use of new studies in the RFC/FNPRM as ex post facto evidence, it apparently overlooks our quite
specific statement therein188 that our decision to adopt the 40 dB/decade standard was based on
information available at the time of the decision, not newly available information.189
76. With regard to the new studies identified in the RFC/FNPRM, ARRL contends that the
major flaw in the NTIA Phase 2 Study is that the modeling used does not fully account for the way that
field strength decays at angles other than 90 degrees. ARRL further argues that with respect to height, the
report errs in its attempted justification of the 5 dB height correction above 30 MHz but not below, and it
justifies 40 dB/decade by disregarding 20 percent of the data points.190 On the other hand, CURRENT
quotes the NTIA Phase 2 Study as stating: "[a]t or above 10 MHz, the simulation results show good
agreement between the rate that field strength decays and the [40 dB/decade] distance extrapolation rate
in the Part 15 rules."191 HomePlug also agrees that the NTIA Phase 2 Study clearly demonstrates that the
40 dB/decade extrapolation factor is the correct value at or above 10 MHz, and much closer below 10
MHz than figures used in the studies submitted by ARRL.192 We observe that NTIA's modeling in its
Phase 2 Study indicates that the field along a complex power line model is highly varied, with areas of
greater and lesser field strength produced by cancellation and reinforcement effects.193 However, there
are some regularities, including field strength maxima at multiples of wavelengths along the power line,
which is the reason why we adopted the requirement for measurements at multiple points along the power
lines in our BPL measurement guidelines. In addition, as discussed above, ARRL's own modeling shows
that the magnetic field (measured below 30 MHz) does not vary greatly with height.194 Further, we agree
with NTIA's position that "the 80th percentile values eliminate the localized peaks that are unlikely to be
encountered by a radio receiver randomly located in close proximity to an Access BPL power line."195
Thus, we find that the NTIA Phase 2 Study is not flawed as argued by ARRL.
77. ARRL next contends that the Brazil Study is deficient in that it does not identify the test
equipment used, the model number of the BPL equipment, the location of the testing, and how the BPL
signal was coupled to the power line, making it difficult to evaluate the accuracy of the report.196


187 UPLC reply comments at 4.
188 The Commission specifically stated in the RFC/FNPRM that it did not rely on NTIA's more recent Phase 2
simulation results to justify its earlier decision. RFC/FNPRM at 9678.
189 While our decisions in the BPL Order and BPL Reconsideration Order were not based on the NTIA Phase 2
Study
and the Brazil Study, as affirmed in the RFC/FNPRM, when we reviewed the issue anew therein, it was
entirely appropriate to consider the information from these two studies in explaining our tentative conclusion in
reviewing this matter that the 40 dB/decade standard should be retained.
190 ARRL reply comments at 19-20.
191 CURRENT comments at 6.
192 HomePlug comments at 7.
193 See Figure 4-2 in NTIA Phase 2 Study, at section 4.2.2.
194 See para. 36 and footnote 83, supra.
195 See NTIA Phase 2 Study at Section 2.3.2.
196 Exhibit B to ARRL comments at 2.
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CURRENT states that despite its weaknesses, including unstated set-up conditions (e.g. cable height) and
too few data points, the Brazil Study shows attenuation over distance in excess of 40 dB/decade, and that
to the extent of its reliability, it supports the Commission's decision. IBEC agrees with ARRL that these
results and the network configurations in this study do not resemble those used in North America and
considers them of limited application.197 We recognize these concerns regarding the Brazil Study. In
addition, like the OFCOM studies before it, the Brazil Study would, in the best of circumstances, provide
only anecdotal information on the attenuation rate of BPL emissions as it only conducted measurements
at a single location, rather than the very large number of sites that would be needed to develop a
generalized description of that parameter. As we stated in the RFC/FNPRM, these studies do, however,
provide an indication that BPL emissions tend to attenuate at rates that vary substantially across different
sites, and that those rates can be much higher than the 20 dB/decade suggested by ARRL. In fact, the
Brazil Study, while not individually probative, provides support for a much higher extrapolation factor
than the similarly insubstantial OFCOM studies provided by ARRL.
78. ARRL states that it also provided a number of modeled studies showing that 40 dB/decade is
not the correct factor to apply below 30 MHz.198 It submits that these studies also showed that at angles
upward from radiating power lines, field strength did increase with height and that the correlation
between measurements made at 1 meter in height, 10 meters horizontally from an overhead power line,
and the field strength at 30-meters distance, at upward angles where amateur HF antennas are most likely
to be located, was very close to 20 dB/decade.199 We agree with ARRL that emissions radiating upwards
from overhead power lines are likely to attenuate at lower rates than emissions radiating horizontally and
lower to the ground. In cases where an amateur antenna is located on a tower above the height of the
power lines, as is typical of fixed amateur stations, we would expect that the level of any emissions
received by that antenna might typically be higher than emissions received by a similar antenna located
below the height of the power lines, all other things the same, because the path to the tower-mounted
antenna will be less affected by the ground. However, our Access BPL rules provide for protection of
such antennas by the absolute application of the prohibition against causing harmful interference in
Section 15.5 of the rules.200 Also we would generally expect that if a BPL installer sees a tower-mounted
antenna, the installer would take steps to avoid interference to it before the system commences operation.
In any case, for safety reasons, our rules provide for measurement of Access BPL systems from locations
relatively close to the ground, where attenuation rates are likely to be higher, rather than at heights similar
to power lines.201
79. ARRL argues a number of technical points to support using the free-space (or near
free-space) 20 dB/decade attenuation rate associated with line sources. It provides a technical description
that in the radiating "near-field" region of a large emitter (at distances beyond /2, where is the


197 ARRL comments at 48, IBEC comments at 2.
198 ARRL comments at 49. ARRL does not specifically identify these studies.
199 ARRL comments at 52-54. ARRL also points out that few if any HF antennas are located at the 1 meter height at
which test may be made under the Access BPL measurement guidelines. We further note that while fixed amateur
HF antennas are indeed typically mounted higher than 1 meter, most mobile HF antennas are likely to be mounted
on vehicles at heights of approximately 1-2 meters.
200 47 C.F.R. 15.5.
201 ARRL itself recognizes the wisdom of making measurements close to the ground and generally supports the
Commission's measurement guidelines, including measuring with a loop antenna at frequencies below 30 MHz, as it
states in its May 2004 comment in this proceeding "ARRL understands and accepts the safety reasons that it is not
practical to make measurements in-situ at heights typical of power lines." See ARRL comments May 2004,
Exhibit D at 27, http://webapp01.fcc.gov/ecfs2/document/view?id=6516182983.
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wavelength of the emission)202, 1) the field strength does not decay uniformly with distance; 2) the field
strength does not have a 377-ohm E (electric) to H (magnetic) field relationship; 3) the fields are not
planar but rather follow a cylindrical Bessel function; 4) emissions along the emitter develop standing
waves in which the magnitude of the fields varies up and down with distance; and 5) the average of
varying fields follows a 1/R or 20 dB/decade attenuation rate with distance.203 ARRL also notes that
there are two types of near-field, reactive and radiating, and that in the reactive near-field region often
assumed to be bounded by a distance of /2 from the radiator, the fields do decay more rapidly than in
the far field.204 Again, we agree with ARRL on all of these technical points of well-documented RF
propagation theory. While we did not explain our earlier decisions on Access BPL at the level of detail
that involved mentioning these factors (and do not believe that it is routinely necessary to explain
propagation considerations which are a matter of accepted electromagnetic physics theory), we did
consider them in our decision. In fact, they were an intrinsic element of our deliberations. As a result, we
included provisions in the Access BPL measurement guidelines for testing along the power lines at
specified intervals where emissions would be expected to be highest.205 We also considered that ground
absorption and other environmental effects present near the surface that limit RF propagation typically
result in attenuation of emissions in the MF and HF bands at rates much higher than the 20 dB/decade
free space model, especially at the 1 meter height specified in the Access BPL measurement guidelines.
80. ARRL contends it is illogical to conclude that, if a 20 dB/decade extrapolation is appropriate
at 30.001 MHz, the extrapolation somehow suddenly jumps to 40 dB/decade at 29.999 MHz. It submits
that the sliding scale formula it had suggested in its petition for reconsideration took into account the fact
that some increase in the extrapolation factor was indeed seen in its analyses at 3.5 MHz, so some
adjustment for a 20 dB/decade factor versus frequency decreases to 3 MHz is appropriate. ARRL argues
that while 40 dB/decade may be appropriate in the reactive near field (within a distance of /2), the
arbitrary specification of 40 dB/decade from 3 to 30 MHz is not supported by electromagnetic physics
theory or any accurate engineering in the proceeding to date. While ARRL is correct with regard to the
physics of this issue, as CURRENT observes, "regulation is often a matter of drawing bright lines through
gray lines."206 The Commission commonly uses "bright line" standards in its rules to provide clarity,
simplicity, predictability and ease of applicability.207 The "bright line" difference in the extrapolation
factors for under and over 30 MHz is intended to provide clear guidance in a region of the spectrum
where there is considerable variability in the predictability of results. We continue to believe that the
current "fixed line" or "bright-line" approach for the different extrapolation factors above and below
30 MHz is appropriate for practical and administrative purposes.208


202 The wavelength of an electromagnetic waveform is given by = V/F, where V is the speed of light and F is the
frequency of the waveform. As an example, the wavelength of a 10 MHz signal is about: 3108 / 10106 = 30
meters.
203 ARRL comments at 49-50 and Exhibit C to ARRL comments.
204 Id., at 56.
205 See BPL Order, Appendix C (Measurement Guidelines) at 21340.
206 CURRENT Technologies comments at 11-12.
207 See for example, 47 C.F.R. 15.107 (a), 15.207 (a), or 15.250 (d). In each of these sections, a different limit
applies to each band of frequencies, despite their adjacency.
208 Courts have found that, in complex areas of regulation, an administrative agency often "must create bright lines
to separate prohibited and permissible activity. We defer to this line-drawing provided the interpretation is both
reasonable and consonant with Congress' intent." Beazer East, Inc. v. United States Environmental Protection
Agency, Region III
, 963 F.2d 603, 610 (3rd Cir., 1992).
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81. ARRL next observes that the NTIA 2004 comments the Commission relied on in part in
some decisions made in the BPL Order provided "significant analyses that showed that if a large number
of BPL emitters are deployed, they will raise the worldwide levels of man-made noise."209 It submits that
these analyses all presumed that the field strength of a BPL system is 29.54 dBV/m at 30-meters
distance and that the angles that will be propagated from overhead BPL lines are all upward from the
[power] line, not downward toward the ground. It contends that for the NTIA Phase 1 modeling of sky
wave propagation to have had any merit at all, the test methods used must have determined accurately the
point of maximum emissions above the power lines and they did not. ARRL submits that its analysis of
the NTIA model showed that if a 40 dB/decade extrapolation is used, the test will not accurately reflect
the actual maximum emissions from these systems, i.e., the emissions above the power lines will
attenuate at 20 dB/decade. ARRL is incorrect in its speculative statement that the NTIA model used the
29.54 dBV/m at 30-meters distance value in accounting for upward propagation when it estimated the
impact of BPL emissions on the levels of background man-made noise. While NTIA did not measure
emissions above the power lines, we would not expect its staff to undertake such a hazardous task.
Moreover, measurements above the power lines are not necessary to the estimation method NTIA used.
The NTIA model does appropriately account for higher levels of radiation above the power line in the far-
field gain pattern input calculated from the VOAAREA power line modeling used in the Phase 1 Study.210
Conversely, ARRL does not provide any information to support its assertion that the model used by NTIA
does not properly estimate the attenuation rate of emissions that might contribute to sky wave
propagation. It merely asserts that "ARRL's analysis of the NTIA model showed that if a 40 dB/decade
extrapolation is used, the test will not accurately reflect the actual maximum emissions from these
systems."211
82. We also observe that in its Phase 2 Study, the NTIA estimates that under conditions of low
solar activity that produce the lowest aggregate BPL signal via ionospheric propagation relative to the
local noise floor at any geographic point, approximately 916,000 overhead BPL devices alone could be
deployed before realizing a 1-dB increase in the noise floor.212 NTIA also found that under high solar
activity, more than 1.35 million overhead BPL devices would be required to raise the noise floor by 1
dB.213 However, most Access BPL installations have a combination of overhead and underground
devices, making the number of BPL devices that can be deployed before a 1-dB increase in the noise floor
occurs much higher than the numbers listed above, depending on the particular combination of overhead
and underground BPL devices.214 Further, if BPL exclusive overhead installations reach such numbers,
the Commission could consider whether a change in its rules to account for a change in the noise floor is
appropriate at that time.
83. ARRL's arguments regarding propagation and the extrapolation factor also address the
behavior of RF fields. It again points to provisions in the rules specifying that at frequencies above
30 MHz, 20 dB/decade is used at the measurement extrapolation factor while at frequencies below 30


209 ARRL comments at 52.
210 VOAAREA is one of the software tools in the NTIA/ITS Voice of America Coverage Analysis Program
(VOACAP) HF Propagation Prediction software suite. The same tool was used in all of the NTIA modeling reports
(NTIA Phase 1 Study, NTIA Technical Appendix and NTIA Phase 2 Study). We would, in fact, expect the
attenuation rate to be much less than 40 dB/decade in skyward directions.
211 ARRL comments at 52.
212 See NTIA Phase 2 Study at Section 5.4.1, Figure 5-4.
213 Id., at Figure 5-3.
214 Id.
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MHz 40 dB/decade is used and presumes this difference is because above 30 MHz, measurements are
made in the far field, while below 30 MHz, measurements are made in the near field.215 ARRL submits
that the way that fields vary in the reactive and radiating near field regions differ. It asserts that in the
reactive near field region, bounded by a distance of /2 , field strength decays at a 40 dB/decade rate and
in the radiating near field region beyond that boundary, fields generally develop a standing-wave pattern
that diminishes with distance, but one that, on the whole, varies at a 20 dB/decade rate. It argues that the
inadequacy of the present BPL rules is due to the fact that the rules assume that all areas below 30 MHz
are in the "near field" region without differentiating between reactive and radiating near field phenomena.
It submits that a 40 dB/decade extrapolation factor beyond the reactive near field region is flawed and at
distances of 10 meters or more from the radiating source, all points are outside the reactive near field
boundary for all frequencies above 4.78 MHz.216
84. In its reply comments, CURRENT argues that ARRL rests much of its argument regarding
the reactive and radiating near field propagation characteristics on a logical error.217 It observes that
ARRL supposes two contradictory propositions to be simultaneously true that: 1) Access BPL systems
comprise large radiating systems and 2) the far field region begins very close to the antenna. It submits
that correcting this error yields a much larger extrapolation factor than ARRL acknowledges. In this
regard, CURRENT states that if the first point is true, that is, if BPL-equipped power lines function as
large, distributed antennas, then the near field extends well beyond 30 meters from the line.218 It submits
that in that case, all extrapolation takes place in the near field and the attenuation with distance is much
steeper in the near field than beyond it, so that regardless of what happens farther out, 40 dB/decade is a
conservative estimate in the near field. CURRENT notes that on the other hand, if ARRL's second
proposition is true, that is, if the far field begins very close to the antenna, it follows that the antenna must
be functioning similarly to a point source, in which case the extrapolation factor is close to 40 dB/decade.
85. The arguments of ARRL and CURRENT concerning the technical validity of using
40 dB/decade as the extrapolation factor for measuring emissions on frequencies below 30 MHz
demonstrate the complexity involved in describing and estimating field strengths in the near-field regions
of emissions. ARRL is generally correct in its technical presentation of the theory of such fields, i.e., that
emissions decay in the reactive near field at a rate of 40 dB/decade within a distance of /2 from the
source and then in the radiating near field out to 2D2/ at a rate of 20 dB/decade. The very long lengths of
typical power line segments therefore would not be expected to affect the decay rate of field strengths
relative to reactive near field phenomena and therefore at distances greater than 10 meters all frequencies
above 4.78 MHz will generally be outside the reactive near field boundary. However, ARRL's
description of the behavior of fields also shows that while the attenuation rate in the radiating near field is


215 ARRL comments at 56-58.
216 ARRL notes that for large line radiators, the calculation of the reactive near field distance is more complex, but
states that it can be approximated by assumption of a line source radiator. ARRL submits that for these radiators,
within the region of /2, the fields do not decay at 40 dB/decade as they do for physically small radiators, but
generally decay up close at approximately 20 dB/decade. It states that beyond the reactive near-field region, the
calculated field strength shows a standing wave, but the peaks of that standing wave, or the average of the fields of
the standing wave, decay at a 20 dB/decade rate. ARRL comments at 57.
217 CURRENT reply comments at 10-11.
218 CURRENT observes that the generally accepted boundary beyond which points are not considered as being in
the radiating near field is 2D2/, where is the wavelength of the emission and D is the largest physical dimension
of the radiating element, CURRENT reply comments, Appendix A at i. In the case of a BPL system, 2D2/ will
typically be much farther than the 30 meter reference distance for the BPL emission limit specified in Section
15.209 of the rules (this measure does not properly describe the near field boundary in the case of emitters as long as
power lines, see for example, ARRL reply comments, Appendix A at 7-8.)
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generally on the order of 20 dB/decade (in the free-space or near free-space case), there are standing wave
patterns and other phenomena that make predictions unreliable. In addition, when measuring relatively
close to the ground (at the 1-meter height specified for measurements at frequencies below 30 MHz), the
proximity to and variation of ground features and other conditions cause great variability in signal
levels.219 ARRL recognizes these ground effects, but argues that licensed services should not be protected
only at ground level and that to do this the extrapolation factor should take into account the normally
encountered antenna height of the victim receiver. Given that BPL measurements will be made close to
the ground for the safety and practical reasons indicated above and the propagation characteristics that are
likely to be present in ground environments, we therefore continue to believe that there is justification for
presuming that the expected attenuation rate of measured emissions at frequencies below 30 MHz is
greater than 20 dB/decade. We also agree with ARRL that licensed services should be protected in all
cases and in this regard, the regime of rules we have established for Access BPL systems, as discussed
above, provides that protection.
86. To further support its argument for an extrapolation factor of 20 dB/decade, ARRL submits
a paper analyzing the industry standards for radiated emissions below 30 MHz.220 It states that there are
very few such standards because regulations for most unlicensed devices control conducted emissions
below 30 MHz and radiated emissions above 30 MHz. It argues that all of these standards stipulate that
electric fields or magnetic fields be extrapolated at 20 dB/decade, except in the reactive near-field region,
nominally considered to be bounded by a distance of /2 from the radiating source.221 On the other
hand, HomePlug observes that these standards basically confirm that there are multiple views of what the
extrapolation factor should be, and that it is generally greater than 20 dB/decade in the near field, and
often 40 dB/decade or more on the lower end of the frequency range. HomePlug asserts that in fact, the
various documents mentioned by ARRL demonstrate that there are different standards with multiple
extrapolation factors -- a fact that HomePlug asserts support the current rule.222 IBEC states that use of
the slant-range approach in determining extrapolated values of the emission standard is a fair compromise
that contemplates the geometry of measuring emissions from power lines in close proximity to the
lines.223
87. We observe that none of the standards mentioned by ARRL apply to Access BPL equipment
and the specific environments in which these devices operate, as discussed above.224 In particular, even


219 ARRL comments at 57.
220 ARRL comments at 58 and Exhibit D to ARRL comments.
221 ARRL lists the following standards: 1) ANSI C63.12:1999 American National Standard Recommended Practice
for Electromagnetic Compatibility Limits; 2) Telcordia GR-1989 Electromagnetic Compatibility and Electrical
Safety - Generic Criteria for Network Telecommunications Equipment; 3) CISPR 18-2 1986 Radio interference
characteristics of overhead power lines and high-voltage equipment -- Part 2: Methods of measurement and
procedure for determining limits; 4) CISPR 11 Industrial, scientific and medical equipment -- Radio-frequency
disturbance characteristics -- Limits and methods of measurement; and 5) 47 C.F.R Part 18 Industrial, Scientific and
Medical Equipment (ISM).
222 HomePlug reply comments at 5. For example, although CISPR 11 uses a 20 dB/decade extrapolation factor,
CISPR 18-2 suggests an extrapolation factor of 33 dB/decade for frequencies below 30 MHz.
223 IBEC comments at 5. It also believes that distances measured to determine the slant range should be to the
closest radiating wire on the power pole. The amended rules provide for determination of the slant range distance
from the power line carrying the BPL signals.
224 For example, CISPR 11 and FCC Part 18 are only applicable to ISM equipment. Telcordia GR 1089 is only
applicable to telecommunications systems. ANSI C63.12 is not a standard but merely a recommended practice.
CISPR 18 only evaluates radio noise generated by high-voltage converter power stations and discusses methods on
(continued....)
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though ARRL insists that the CISPR 18 standard does apply to BPL as it would apply to any source of RF
noise,225 we note that CISPR has been working on the subject of an emission standard for BPL as far back
as 2000 under CISPR Subcommittee G. The work to develop a standard specific to BPL has continued in
CISPR Subcommittee I, however, this work has been recently reset to its preliminary stage due to the
complex issues surrounding RF emissions at frequencies below 30 MHz, with signal attenuation being
highly variable depending on the localized environment, as we discussed above.226 Moreover, we find
that the record in this proceeding has established a substantial body of information that supports the use of
40 dB/decade in conjunction with slant-range distance to adjust the emissions level for test results
obtained in accordance with the measurement standards we have adopted for Access BPL.
88. In addition, as we discussed in the RFC/FNPRM, the slant-range distance method in the
Access BPL measurement guidelines works with the 40 dB/decade factor to yield extrapolated emissions
level values that have the effect of imposing a more conservative emissions standard than would be
derived using the horizontal (lateral) distance from the nearest point of the overhead power line carrying
the BPL signals.227 In this regard, at the relatively short distances at which Access BPL emissions are to
be measured, i.e., distances 30 meters or less, applying the slant-range measurement method in the
extrapolation of the measurements effectively reduces the compliant emission levels for BPL systems
with respect to the horizontal distance from the power line. This reduction results because at any given
horizontal distance from the power line, the slant-range distance is longer than the horizontal distance.
The relationship is one of basic plane geometry that occurs due to the height of the power line on which
the BPL signal injector is installed.228 When extrapolated values at 40 dB per decade of slant-range
distance are plotted against the horizontal distance, the effective extrapolated emission level curve more
closely follows the emission level curve based on a 20 dB per decade extrapolation factor at horizontal
(Continued from previous page)


how to reduce radio noise from inherent power line components, such as mercury arc and thyristor valves. Although
CISPR 18-2 discusses the attenuation of noise sources with distance from the power lines, we note that this standard
states (and ARRL points out) that "an attenuation factor of 33 dB/decade is somewhat valid for frequencies between
1.7 MHz and 30 MHz." See CISPR 18-2, Section 2.3.5.1; see also Exhibit D to ARRL comments at 5.
225 See ARRL ex parte comments filed January 11, 2010 at 3.
226 See the work of CISPR Subcommittee I at http://www.iec.ch/cgi-
bin/procgi.pl/www/iecwww.p?wwwlang=E&wwwprog=sea1112.p&committee=CIS%2FI&class=&refno=&type=&
date.
227 The rules for testing Part 15 devices specify that "[t]o the extent practicable, the device under test shall be
measured at the distance specified in the appropriate rule section. The distance specified corresponds to the
horizontal [emphasis added] distance between the measurement antenna and the closest point of the equipment
under test, support equipment or interconnecting cables as determined by the boundary defined by an imaginary
straight line periphery describing a simple geometric configuration enclosing the system containing the equipment
under test." 47 C.F.R. 15.31(f). However, for Access BPL devices operating on overhead power lines, the
Commission adopted the slant range method due to the location of the BPL device on a power pole that is typically
several meters above ground and above the measurement antenna. See Guidelines in Appendix C of BPL Order at
21339-21343 and Figure 1 in Appendix D, infra.
228 The geometric relationship between horizontal and slant distances is that of a right triangle in which the
hypotenuse is equal to the square root of the sum of the squared lengths of the other two sides, i.e., h = (x2 + y2).
For example, using a 40 dB per decade distance extrapolation factor, the maximum permitted emission level at a
horizontal distance of 10 meters from the power line is 48.6 dBV/m. However, for that same horizontal distance of
10 meters, the slant distance is 14.9 meters (assuming the power line is 12 meters in height, thus the measurement
height with the antenna at 1 meter from the ground would be 11 meters) making the maximum permitted emission
level to be only 41.7 dBV/m, a level that is 7 dB more stringent. This means that instead of being able to emit up
to 48.6 dBV/m, an Access BPL device could only emit 41.7 dBV/m, a level 7 dB less than if horizontal distance
as specified for other Part 15 devices was used in the calculation of extrapolated levels. See illustrations and
formulae in Appendix E, infra.
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distances than the emission level curve based on a 40 dB per decade extrapolation factor at horizontal
distances.229 NTIA's modeling results in its Phase 2 Study effectively reflect this observation.230 Also,
given that the Access BPL measurement guidelines require compliance measurements to be taken at 30
meters or less, the effect of the slant-range distance provision is significant at all distances where the
extrapolation factor can be used.231 As shown in Appendix E, infra, the extrapolated Access BPL
emissions level based on the existing 40 dB/decade factor and the slant-range measurement approach is
very close (within a 5 dB range for typical medium-voltage power line heights) to the level that would
result from use of the 20 dB/decade extrapolation factor with the traditional horizontal measurement
distance.232
89. ARRL and several of the commenting parties address our request for comment on whether it
would be desirable to modify the extrapolation factor to be 30 dB/decade or some other value to account
for the considerable variability around the 40 dB/decade expected attenuation value at different sites. Our
intent was that this lower value would apply a more conservative approach that would compensate for
those cases where the actual attenuation is less than 40 dB. In opposing this plan, ARRL asserts that the
Commission is not apparently convinced by its own ex post argument justifying use of 40 dB/decade, as it
immediately thereafter abandoned that argument and proposed instead to adopt an equally unjustified
30 dB/decade extrapolation factor in what appears to be the "King Solomon" approach rather than a real
scientific analysis. ARRL rejects the approach underlying the 30 dB/decade proposal and argues that the
Commission is obligated to adopt a scientifically valid extrapolation standard, which it contends is
20 dB/decade.233 The UTC and CURRENT also oppose such a change, stating that the Commission was
correct to select 40 dB/decade as the distance extrapolation and that we should maintain that value.
UPLC argues that a 30 dB/decade value would be inappropriate and that a reduced value would impose a
significant compliance burden on Access BPL systems.234 CURRENT argues that the Commission's
original selection of 40 dB/decade is well supported by the record and that the mere possibility of other
supportable conclusions, especially if based on other studies, does not warrant a change.235 CURRENT
and the UTC further submit that the now-demonstrable lack of interference reports from CURRENT's


229 See illustration in Figures 1-3 in Appendix E, infra.
230 See NTIA Phase 2 Study, at Section 2.5. NTIA found that "the Commission's modification to the rules for
distance extrapolation [by using slant distance instead of horizontal distance for Access BPL devices] resulted in
good agreement between the extrapolated field strength level and the rate in which field strength decays from the
overhead MV power line."
231 RFC/FNPRM at 21280. Because the slant range distance is dependent on the height of the power line on which
the Access BPL equipment is installed, the extrapolated emission levels vary the most when the horizontal distance
between the center of the measurement antenna and the nearest point directly under the overhead power line
carrying the BPL signal is between 5 meters and 20 meters, with the maximum difference between the slant range
and horizontal approaches at around 10 meters. See illustrations in Exhibit E, infra.
232 Appendix E, infra, shows that for power line heights of 10 meters, the extrapolated emission level using 40
dB/decade in conjunction with slant distance is 4.4 dB less stringent than the use of 20 dB/decade with horizontal
(lateral) distance, when the measurement antenna is placed at a horizontal distance of 10 meters from the nearest
point directly under the overhead power line carrying the BPL signal. For power line heights of 12 meters, the
extrapolated emission level using 40 dB/decade in conjunction with slant distance is 2.7 dB less stringent than the
use of 20 dB/decade with horizontal distance, when the measurement antenna is placed at a horizontal distance of 10
meters from the nearest point directly under the overhead power line carrying the BPL signal.
233 ARRL comments at 59.
234 UPLC comments at 5-6.
235 CURRENT comments at 8.
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extensive operations supports not changing the extrapolation standard.236
90. It is plain from the record that reducing the extrapolation factor to the more conservative
30 dB/decade level to compensate for those situations in which the actual attenuation is less than
40 dB/decade would not satisfy the concerns of any of the parties to this matter or otherwise provide any
benefits that would improve our Access BPL measurement guidelines. Contrary to ARRL's
misapprehension, our consideration of a reduction in the extrapolation factor was not intended as a
"compromise" approach in consideration of the wide variations in the studies and data before us. Rather,
it was a recognition of the uncertainty or inexactness inherent in the information available and the amount
of analysis undertaken at the time, and a signal of our openness in reconsidering the issue in that light.
91. Taking into consideration the above evaluations and all of the additional information before
us now, we believe that the most compelling path points to retaining the 40 dB extrapolation factor. In
this regard, we first observe that we have used this extrapolation value successfully with measurements at
frequencies below 30 MHz in our program to control emissions from radio frequency devices for many
years. This includes not only consumer products, but also industrial, scientific and medical equipment
that may use thousands of watts of power and couple radio noise onto power lines that can radiate for
significant distances. In addition, while ARRL asserts that there is only one scientifically correct and
valid answer of an extrapolation factor of 20 dB, the studies and information before us show considerable
differences in extrapolation factors under various system configurations and usage condition. We
therefore conclude that there is no single "right" value for the extrapolation factor that accurately reflects
environmental conditions in all cases, and instead find that the most appropriate decision is to use the
existing value in the rules that both has a scientific basis and has stood the test of time for a wide variety
of devices and systems. We also consider that, as observed in the discussion above, using the slant range
to perform measurements has the effect of reducing the extrapolation factor to approximately 20 dB. In
addition, the attenuation factors that are typically present when making measurements close to the ground,
as specified in the BPL rules, tend to increase the signal loss above that which occurs from the spreading
of energy in free space propagation. Finally, while one can debate the propriety and scientific validity of
any particular extrapolation factor, we must consider that the extrapolation factor is but one element in the
context of an overall set of rules that are designed to minimize the risk of harmful interference and to put
in place appropriate measures to eliminate such interference if it should occur. Whether the extrapolation
factor is 20 dB or 40 dB or somewhere in between is far less important than the fact that harmful
interference must be corrected under any circumstances. While ARRL asserts that an extrapolation factor
that is too lax will lead to widespread instances of harmful interference that should be corrected ex ante as
opposed to ex post, we have seen little evidence of harmful interference being caused.237 Accordingly, we
are not modifying the extrapolation factor for the emissions standard for frequencies below 30 MHz to
compensate for the variability in the field strength attenuation rate at different locations.
92. We also are reiterating here the clarification we issued in the RFC/FNPRM that
measurements of BPL equipment and systems should be made at the 30-meters distance specified in
Section 15.209 unless circumstances such as high ambient noise levels or geographic limitations are
present, in which case, a 3-meter or 10-meter horizontal distances indicated in the BPL measurement
guidelines may be used.238 We are further clarifying that measurements made at the 30-meter distance


236 CURRENT comments at 8; UPLC comments at 5. We note that CURRENT's operations are mainly above 30
MHz on overhead MV lines.
237 As noted above, the BPL system database shows that BPL systems are currently operating in 125 zip codes
across the United States.
238 No extrapolation of the emissions level is needed for measurements made at the 30-meter distance specified in
the standard.
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specified in the Section 15.209 emissions standard will prevail over measurements made at shorter
distances and that where possible and practical, the Commission's staff will make measurements at this
distance when testing for compliance.239 As indicated above, to provide additional clarity in our
compliance requirements, we are also amending the BPL measurement guidelines to specify the
extrapolated values of the emissions level for compliance at 3-meter and 10-meter horizontal distances
from the nearest point of the overhead power line carrying the BPL signals for typical heights of medium
voltage power lines. These clarifications of the existing rules as well as the adoption of the definition for
slant-range distance would assist the industry in ensuring compliance of BPL systems without imposing
additional regulatory costs.
2.

Site-Specific Extrapolation Factors

93. In the RFC/FNPRM, the Commission proposed to allow parties testing BPL systems for
compliance with the radiated emissions limits to determine distance correction factors on a site-by-site
basis using a new in situ measurement procedure designed specifically for Access BPL.240 This plan,
which was based on a concept under consideration in the IEEE Working Group P1775/D2 effort at that
time and which has been finalized since,241 would allow entities conducting measurements of Access BPL
systems and equipment to determine an extrapolation factor specific to a site by fitting a straight line to
measurements of field strength in dBV/m vs. logarithmic distance in meters from the nearest conductor
carrying BPL emissions, where the extrapolation factor would be taken as the slope of that line.242 The
Commission indicated that the site-specific extrapolation factor would be an alternative to the
extrapolation factor specified in the BPL measurement guidelines and would be replacing the existing
method using only two data points for determining site-specific extrapolation factors currently in the
rules.243 The proposed alternative method would only be applicable to Access BPL devices operating on
frequencies below 30 MHz.
94. Under the proposal in the RFC/FNPRM, entities conducting measurements would determine
an extrapolation factor specific to the site by fitting a straight line to measurements of field strength in
dBV/m vs. logarithmic distance in meters from the nearest conductor carrying BPL emissions, where the
extrapolation factor would be taken as ten times the slope, n, of that line. The slope n any point on the
straight line in V/m would be:


239 CURRENT states that while it has no objection in principle to measurement of BPL emissions at 30 meters, it
does foresee possible problems in practice. In this regard, CURRENT submits that a suitable test site would have to
be removed from power lines (apart from the one under test) by a distance of several times 30 meters. Such a
location will be difficult to find in a built-up environment, so studies may have to take place in rural areas.
CURRENT comments at 11. We agree with this observation and caution parties taking measurements at 30 meters
(and also at closer distances) to take into account the presence of other nearby power lines which may also be
carrying BPL signals or be a source of ambient noise.
240 Section 15.31(f)(2) of the rules currently allows the results of measurements performed at frequencies below 30
MHz to be extrapolated on a site-specific basis, specifying that test results are to be extrapolated to the standard
distance by making measurements at a minimum of two distances on at least one radial to determine the proper
extrapolation factor, see 47 C.F.R. 15.31(f)(2).
241 See IEEE 1775-2010 at Annex A, p. 41-43.
242 See RFC/FNPRM at 9682-9684.
243 Currently, for frequencies below 30 MHz, the rules stipulate that "[w]hen performing measurements at a closer
distance than specified, the results shall be extrapolated to the specified distance by either making measurements at a
minimum of two distances on at least one radial to determine the proper extrapolation factor or by using the square
of an inverse linear distance extrapolation factor (40 dB/decade)." 47 C.F.R. 15.31(f)(2).
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(20logEr 20logE2)/(10logD2 10logDr)
where Er is the measured field strength at distance Dr
The field strength in dBV/m at any distance D along the best straight line fit is estimated from the
value of n as:
20logEr = 20logE2 + n(10logD2 10logDr)
The extrapolation factor would be derived from a best straight line fit determined by a linear least
squares regression calculation from measurements made at four or more lateral distances from the
overhead line, starting at no less than 6 meters from the lateral plane and spaced from each other by at
least 3 meters. If these measurements allow a straight line with a negative slope to be calculated or
drawn with reasonable fit (the minimum regression coefficient of multiple correlation would be 0.9),
the best straight line fit would be used to calculate field strength at the 30-meters standard
measurement distance in the rules according to the equation above. If the four measurements do not
fall near any straight line or negative slope, measurements at a new distance would be added until a
reasonable fit to a straight line is indicated. In addition, measurements that obviously show a "null"
or other "outlier" value would be ignored.244 Parties employing site-specific extrapolation values
would be required to provide a record of the measurements under the above procedure and to submit
those measurements and their derivation of the in situ values with any measurements with compliance
submissions to the Commission.
95. Several commenting parties representing the Access BPL industry support our proposal to
establish a special procedure for determining site-specific extrapolation factors for use in measuring
emissions from BPL systems and equipment. In particular, CURRENT, HomePlug, IBEC, Intellon
Corporation (Intellon) and UTC support allowing BPL systems operators to develop their own in situ
BPL extrapolation factors on a voluntary basis as a means to provide them with flexibility in
demonstrating compliance with the rules.245 IBEC states that in certain cases it may be advantageous to
create special procedures to address unique site-related issues. It submits that these special procedures
should be implemented at the option of the equipment manufacturer, who should also bear the
responsibility for justifying the procedures and ensuring that they meet the requirements and intent of the
rules.
96. ARRL opposes the establishment of a procedure for determining site-specific extrapolation
factors for Access BPL measurements, arguing that our proposal "is flawed and unacceptable, based on
an incomplete IEEE standard which is still under development, and not yet published."246 It further
observes that the IEEE draft standard has been the subject of a number of negative comments in the ballot
process, which must yet be addressed by the IEEE's working group.247 With regard to methodology,
ARRL argues that measurement at only four points (as proposed in the IEEE draft standard) cannot


244 "Outliers" are high and low values that fall well out of the range of typical values.
245 CURRENT comments at 8, HomePlug comments at 4-5, IBEC comments at 3, Intellon reply comments at 5 and
UPLC comments at 7. CURRENT indicates that it supports this proposal so long as the manufacturer also retains
the option of applying the fixed extrapolation factor in the rules.
246 ARRL comments at 18.
247 We note that the IEEE did adopt a standard for determining site-specific extrapolation factors in measuring
emissions from BPL systems (IEEE 1775-2010 Standard, published on Jan 7, 2011) that includes the methodology
proposed in the draft standard. However, we also note that the IEEE EMC Society did not support that standard,
citing deficiencies on procedural and substantive grounds; nonetheless, IEEE 1775-2010 remains a published and
valid standard, sponsored and supported by the Power System Communications Committee of the IEEE Power &
Energy Society and the Standards Committee of the IEEE Communications Society.
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determine the actual extrapolation value, because any attempt to apply any measurement of extrapolation
to the power lines' complex environment is a recipe for inaccuracy and would encourage "cherry picking"
the results. It contends that this would allow those doing the measurements to provide any value of
extrapolation that they want in either direction.248
97. In their reply comments, HomePlug and Intellon submit that contrary to ARRL's position,
the IEEE draft standard on Access BPL site-specific extrapolation values currently is under review by a
large and competent body of experts who have studied and validated the in-situ measurement
procedures.249 They state that even as a draft, this standard represents the most recent collaborative work
to accurately measure radiation specifically from power lines carrying BPL signals.
98. We continue to believe the availability of a site-specific approach for determining values for
extrapolation of measurements of Access BPL emissions on frequencies below 30 MHz is a desirable and
useful alternative to the fixed extrapolation factor. The option to use site-specific values can substantially
alleviate the measurement concerns associated with the standard extrapolation factor and the variability in
attenuation rates that may be observed in the field, and particularly where measurements at a site may
plainly not appear to conform to the 40 dB/decade standard.250 We also recognize ARRL's concerns that
a site-specific option could be abused by careful selection of measurement points. However, we find that
our proposed approach that requires four measurements spaced at least 3 meters apart with provisions for
additional measurements where a straight line with a negative slope is not approximated by the four initial
measurements, is sufficient to develop a reliable indication of the attenuation rate at a site. In particular,
we believe the requirement in this new procedure that the measurements used to develop the extrapolation
value approximate a straight line with a negative slope as determined through the linear least squares
regression method (with a minimum regression coefficient of multiple correlation of 0.9) will adequately
guard against the "cherry picking" concern mentioned by ARRL. Where such a line cannot be
approximated, we will also require that measurements be made at a different perpendicular position along
the power line very nearby or at the same perpendicular position but on the opposite side of the line from
the first set of measurements.
99. This new site-specific procedure will replace the existing Section 15.31(f)(2) alternative for
Access BPL that only requires two measurements. This plan conforms substantially to the
IEEE P1775-2010 standard which has been developed, as HomePlug and Intellon point out, by a body of
experts. We observe that a straight line best fit of multiple data points using the least squares regression
technique is not a new idea developed by the IEEE standard, it is a well-established and commonly used
statistical method. We note that in the RFC/FNPRM, we proposed to derive the extrapolation factor from
a best straight line fit determined by a linear least squares regression calculation from measurements
made at four or more lateral distances from the overhead line, starting at no less than 6 meters from the
lateral plane and spaced from each other by at least 3 meters; at that time, the IEEE standard was in a state


248 ARRL comments at 54. ARRL also submits a paper in Exhibit C of its comments describing that near-field
measurements contain a high degree of variability and that a few meters along the line will make a significant
difference in the rate at which the signal strength decays perpendicular to the line, making any measurement
unreliable for determining an extrapolation value, even at ground level. ARRL argues that, based on the conclusions
of its Exhibit C, it is not possible to measure actual signal levels in the complex in-situ environment surrounding the
power lines, unless a very large number of measurements can be made; thus, 4 measurement points as proposed by
IEEE will not yield an accurate, reliable or predictable extrapolation number, ARRL comments at 55 and Exhibit C.
249 HomePlug reply comments at 4-5, Intellon reply comments at 5.
250 For example, development of a site-specific extrapolation value might be needed if the equipment that has been
tested and found to comply with the emissions limit at other sites is found to be out of compliance as installed at the
site under test.
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of transition and we were merely proposing a measurement concept. We now observe the
IEEE P1775-2010 has finalized its standard to specify that measurements be made at four or more lateral
distances from the overhead line, starting at no less than 3 meters from the lateral plane and spaced from
each other by at least 3 meters. We are adopting the distances as specified in the IEEE published standard
for the new site-specific measurement procedure. This procedure is an improvement over the current
procedure for determining site-specific extrapolation factors in Section 15.31(f)(2) of the rules, which
requires only two measurement points without any specific separation distance, as stated above. We
caution parties responsible for certification measurements to bear in mind that the objective of the
site-specific procedure is to plot enough data points to draw a valid extrapolation curve; accordingly, in
some situations the number of measurement points may need to exceed the recommended minimum for
the resulting extrapolation to be valid.251 Further, as we stated in the BPL Order and the BPL
Reconsideration Order
, operators of Access BPL systems are responsible for eliminating any harmful
interference that may occur or must cease operation upon notification by a Commission representative
that the device is causing harmful interference.252 Accordingly, we are amending our rules as set forth in
Appendix C to establish a new method for determining site-specific extrapolation values for Access BPL
measurements as described herein. Because this is an alternative method intended to facilitate
compliance measurements which may be used at the BPL operator's discretion, the requirement provides
benefits without imposing additional regulatory costs. The benefits of having this additional method
would enable BPL operators to better adjust the operating parameters of BPL devices according to
specific installation sites that might not conform to the standard extrapolation value, which could lead to
cost savings and reduced interference potential. Additional provisions of this procedure are set forth in
the revised Access BPL measurement guidelines in Appendix D.
100. We will not allow the site-specific procedure to be used at locations within 30 meters of a
power pole with a ground conductor where the Access BPL signals devices are carried on a
neutral/grounded line of the power system. In this regard, we are concerned that emissions from a
grounding conductor mounted on the side of a power line pole could combine with the emissions from the
overhead neutral power line to produce false indications of the attenuation rate that would distort the
slope of the extrapolation curve. Accordingly, we are amending our rules as set forth in Appendix C to
establish a new method for determining site-specific extrapolation values for Access BPL measurements
as described herein. Additional provisions of this procedure are set forth in the revised Access BPL
measurement guidelines in Appendix D.

C.

The Access BPL Database

101. ARRL contends that the BPL database is virtually useless due to errors, omissions and
listings of systems that are not operating any longer and systems that have never been placed in operation.
It cites as an example an incident in which it sent an e-mail message to the person listed in the database
for the Manassas, VA, BPL system, it found the e-mail contact was invalid and follow-up e-mail
messages to the City of Manassas went unanswered.253 In its reply comments, the City of Manassas
submits that when the system operator, Comtek, transferred operation of the system to the city, the
contact was not updated immediately but the error was corrected promptly in April 2009 when the city
was notified by ARRL that the listing was incorrect.254 We agree with ARRL that the database should be


251 A valid extrapolation curve would have a minimum regression coefficient of multiple correlation of 0.9.
252 BPL Order at 21276; BPL Reconsideration Order at 9327.
253 ARRL comments at 59-60.
254 City of Manassas, VA comments at 1-2. The City of Manassas also states that amateurs in Northern VA knew
who to contact regarding its BPL system.
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maintained with accurate, up-to-date information. Our staff contacted the database manager, UTC, about
ARRL's concerns and in its reply comments, UTC affirms that the database has been and is being
reviewed periodically to ensure that the information is currently accurate.255 We do note that while it is
important that the database be up-to-date in all respects, it is most important that operating and soon-to-be
operating systems not be omitted and we do not have information that such systems were not or are not
listed. We therefore encourage UTC to continue to be diligent in its management of the database and
other interested parties to work with UTC in providing information to ensure that the records in the
database are accurate and up-to-date.

IV.

PROCEDURAL MATTERS

102. Final Regulatory Flexibility Analysis. As required by the Regulatory Flexibility Act, 5
U.S.C. 603, the Commission has prepared a Final Regulatory Flexibility Analysis (FRFA) of the
possible significant economic impact on small entities of the proposals suggested in this document. The
FRFA is set forth in Appendix B.
103. Paperwork Reduction Act. This document contains no new or modified information
collection requirements subject to the Paperwork Reduction Act of 1995 (PRA), Public Law 104-13. In
addition, therefore, it does not contain any new or modified "information collection burden for small
business concerns with fewer than 25 employees," pursuant to the Small Business Paperwork Relief Act
of 2002, Public Law 107-198, see 44 U.S.C. 3506(c)(4).
104. Congressional Review Act. The Commission will send a copy of this Second Report and
Order in a report to be sent to Congress and the Government Accountability Office pursuant to the
Congressional Review Act, see 5 U.S.C. 801(a)(1)(A).

V.

ORDERING CLAUSES

105. Accordingly, IT IS ORDERED that pursuant to pursuant to the authority contained in
Sections 4(i), 301, 302, 303(e), 303(f) and 303(r) of the Communications Act of 1934, as amended, 47
USC Sections 154(i), 301, 302, 303(e), 303(f) and 303(r), this Second Report and Order is hereby
ADOPTED and Part 15 of the Commission's Rules ARE AMENDED as set forth in Appendix C,
effective 30 days after publication in the Federal Register.


255 UPLC reply comments at 8.
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106. IT IS FURTHER ORDERED that the Commission's Consumer and Governmental
Affairs Bureau, Reference Information Center, SHALL SEND a copy of this Second Report and
Order, including the Final Regulatory Flexibility Analysis, to the Chief Counsel for Advocacy of the
Small Business Administration.
FEDERAL COMMUNICATIONS COMMISSION
Marlene H. Dortch
Secretary
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APPENDIX A

Parties Submitting Comments

Comments

1. The Arkados Group, Inc. (Arkados)
2. The National Association for Amateur Radio (ARRL)
3. Neville Bedford
4. Jeff Beiermann
5. Michael J. Brenza
6. Don Bullard
7. CURRENT Technologies, LLC (CURRENT)
8. James R. Devillier
9. Malachi Doane
10. Michael Elcsisin
11. Roy Gilbert
12. Kurt Harnish
13. The HomePlug Powerline Alliance (HomePlug)
14. The Intellon Corporation (Intellon)
15. The International Broadband Electric Communications, Inc. (IBEC)
16. Morris Jones
17. Neil Klagge
18. Erik Laymon
19. Wayne Longman
20. Gregory r. Marino
21. John Mattesini
22. Timothy J. Newton
23. SPiDCOM Technologies, S.A.
24. Andrew Stenberg
25. Jack L. Sykes
26. David Tessitore
27. The Utilities Telecom Council (UTC)
28. Thomas M. Walsh
29. James Edwin Whedbee, M.Ed. (James Whedbee)
30. Keith Whitaker
31. Larry Yonge

Reply Comments

1. Ambient Corporation (Ambient)
2. The Arkados Group, Inc.
3. The National Association for Amateur Radio
4. The City of Manassas, VA (City of Manassas)
5. CURRENT Technologies, LLC
6. The HomePlug Powerline Alliance
7. The Intellon Corporation
8. The United Power Line Council
9. James Edwin Whedbee, M.Ed.
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APPENDIX B

Final Regulatory Flexibility Analysis

As required by the Regulatory Flexibility Act (RFA),1 an Initial Regulatory Flexibility Analysis
(IRFA) was incorporated in the Request for Comment and Further Notice of Proposed Rulemaking
(RFC/FNPRM)
in ET Docket Nos. 04-37 and 03-104.2 The Commission sought written public comment on
the proposals in the RFC/FNPRM, including comment on the IRFA. This present Final Regulatory
Flexibility Analysis (FRFA) conforms to the RFA.

A. Need for, and Objectives of, the Second Report and Order.

The Second Report and Order maintains the existing Access BPL emissions standards and other
technical operation rules, as well as the existing extrapolation 40 dB/decade factor prescribed in the rules
for use in measurement of emissions from Access BPL systems. In addition, the Second Report and
Order modifies the rules to 1) require a deeper notch filter depth when a notch filter is used to avoid
interference to a specific frequency band; 2) adopt a definition for the slant-range distance used in the
BPL measurement guidelines to further clarify its application; and 3) establish a new procedure for
determining site-specific extrapolation factors.
The decisions in the Second Report and Order are consistent with the mandate by the United
States Court of Appeals for the District of Columbia in ARRL v. FCC, and will provide regulatory
certainty for both manufacturers of Access BPL equipment and systems operators so that development of
equipment and construction of facilities can proceed unimpeded by any concerns about the status of the
regulations with which equipment and systems must comply.3

B. Statement of Significant Issues Raised by Public Comments in Response to the IRFA.

There were no public comments filed that specifically addressed the rules and policies proposed
in the IRFA.

C. Response to Comments by the Chief Counsel for Advocacy of the Small Business
Administration

Pursuant to the Small Business Jobs Act of 2010, the Commission is required to respond to any
comments filed by the Chief Counsel for Advocacy of the Small Business Administration, and to provide
a detailed statement of any change made to the proposed rules as a result of those comments. The Chief
Counsel did not file any comments in response to the proposed rules in this proceeding.


1 See 5 U.S.C. 603. The RFA, see 5 U.S.C. 601-612, has been amended by the Small Business Regulatory
Enforcement Fairness Act of 1996 (SBREFA), Public Law No. 104-121, Title II, 110 Stat. 857 (1996), and the
Small Business Jobs Act of 2010, Public Law No. 111-240, 124 Stat. 2504 (2010).
2 Request for Further Comment and Further Notice of Proposed Rulemaking in ET Dockets No. 04-37 and 03-104
(Amendment of Part 15 Regarding New Requirements and Measurement Guidelines for Access Broadband Over
Power Line Systems, Carrier Current Systems)
, 24 FCC Rcd 9669 (2009) (RFC/FNPRM).
3 See American Radio Relay League, Incorporated, v. Federal Communications Commission (ARRL v. FCC), 524
F.3d 227 (D.C. Cir. 2008).
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D. Description and Estimate of the Number of Small Entities to Which the Rules Will Apply.

The RFA directs agencies to provide a description of, and, where feasible, an estimate of the
number of small entities that may be affected by the proposed rules, if adopted.4 The RFA defines the
term "small entity" as having the same meaning as the terms "small business," "small organization," and
"small business concern" under Section 3 of the Small Business Act.5 Under the Small Business Act, a
"small business concern" is one that: (1) is independently owned and operated; (2) is not dominant in its
field of operations; and (3) meets may additional criteria established by the Small Business
Administration (SBA).6
Nationwide, there are a total of approximately 27.5 million small businesses, according to the
SBA.7 A "small organization" is generally "any not-for-profit enterprise which is independently owned
and operated and is not dominant in its field."8 Nationwide, as of 2002, there were approximately 1.6
million small organizations.9 The term "small governmental jurisdiction" is defined generally as
"governments of cities, towns, townships, villages, school districts, or special districts, with a population
of less than fifty thousand."10 Census Bureau data for 2002 indicate that there were 87,525 local
governmental jurisdictions in the United States.11 We estimate that, of this total, 84,377 entities were
"small governmental jurisdictions."12 Thus, we estimate that most governmental jurisdictions are small.
The adopted rules pertain to manufacturers of unlicensed communications devices. The
appropriate small business size standard is that which the SBA has established for radio and television
broadcasting and wireless communications equipment manufacturing. The Census Bureau defines this
category as follows: "This industry comprises establishments primarily engaged in manufacturing radio
and television broadcast and wireless communications equipment. Examples of products made by these
establishments are: transmitting and receiving antennas, cable television equipment, GPS equipment,
pagers, cellular phones, mobile communications equipment, and radio and television studio and
broadcasting equipment."13 The SBA has developed a small business size standard for firms in this


4 See 5 U.S.C. 603(b)(3).
5 Id. 601(3).
6 Id. 632.
7 See SBA, Office of Advocacy, "Frequently Asked Questions," http://www.sba.gov/advo/stats/sbfaq.pdf (accessed
Dec. 2010).
8 5 U.S.C. 601(4).
9 Independent Sector, The New Nonprofit Almanac & Desk Reference (2002).
10 5 U.S.C. 601(5).
11 U.S. Census Bureau, Statistical Abstract of the United States: 2006, Section 8, page 272, Table 415.
12 We assume that the villages, school districts, and special districts are small, and total 48,558. See U.S. Census
Bureau, Statistical Abstract of the United States: 2006, section 8, page 273, Table 417. For 2002, Census Bureau
data indicate that the total number of county, municipal, and township governments nationwide was 38,967, of
which 35,819 were small. Id.
13 U.S. Census Bureau, 2007 NAICS Definitions, "334220 Radio and Television Broadcasting and Wireless
Communications Equipment Manufacturing"; http://www.census.gov/naics/2007/def/ND334220.HTM#N334220.
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category, which is: all such firms having 750 or fewer employees.14 According to Census Bureau data
for 2007, there were a total of 939 establishments in this category that operated for part or all of the entire
year. Of this total, 784 had less than 500 employees and 155 had more than 100 employees.15 Thus,
under this size standard, the majority of firms can be considered small.

E. Description of Projected Reporting, Record keeping and Other Compliance Requirements.

The Second Report and Order does not contain new or modified information collection
requirements. The minor modified technical requirements adopted in this Second Report and Order, as
discussed below, do not impose significant burden and will not have a significant economic impact on a
substantial number of small entities that are, or may be, subject to the requirements of the rules in the
item.

F. Steps taken to Minimize Significant Economic Impact on Small Entities and Significant
Alternatives Considered.

The RFA requires an agency to describe any significant alternatives that it has considered in
reaching its proposed approach, which may include the following four alternatives (among others): (1) the
establishment of differing compliance or reporting requirements or timetables that take into account the
resources available to small entities; (2) the clarification, consolidation, or simplification of compliance or
reporting requirements under the rule for small entities; (3) the use of performance, rather than design,
standards; and (4) an exemption from coverage of the rule, or any part thereof, for small entities.16
In this Second Report and Order, we modify our rules and measurement procedures for Access
BPL devices operating below 30 MHz to 1) require a deeper notch filter depth when a notch filter is used
to avoid interference to a specific frequency band; 2) establish a new procedure for determining site-
specific extrapolation factors; and 3) adopt a definition for the slant-range distance used in the BPL
measurement guidelines to further clarify its application. In reviewing the requirement for a 20-dB
notching capability and current developments in BPL equipment, we now find that it would be
appropriate to increase the required notching capability of Access BPL systems operating below 30 MHz
to 25 dB from the existing requirement of 20 dB, when a notch filter is used to avoid interference to a
specific frequency band. This deeper notching capability is technologically available and voluntarily
implemented in the field by Access BPL operators to avoid potential interference to amateur radio
operators; therefore, the new requirement would not pose a substantial burden on Access BPL
manufacturers. To afford manufacturers time to redesign their equipment to comply with the new, more
conservative 25-dB notching requirement, we are allowing an 18-month period from the date this action is
published in the Federal Register before the requirement becomes effective.
We further establish an alternative method to allow parties testing BPL systems for compliance
with the radiated emissions limits to determine distance correction factors on a site-by-site basis using an
in situ measurement procedure when measurements cannot be made at the reference measurement
distance of 30 meters as specified in the rules. Because this is an alternative method intended to facilitate
compliance measurements which may be used at the BPL operator's discretion, the requirement provides
benefits without imposing additional regulatory costs. The benefits of having this additional method


14 13 C.F.R. 121.201, NAICS code 334220.
15 http://factfinder.census.gov/servlet/IBQTable?_bm=y&-fds_name=EC0700A1&-geo_id=&-_skip=300&;-
ds_name=EC0731SG2&-_lang=en.
16 5 U.S.C. 603(c).
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would enable BPL operators to better adjust the operating parameters of BPL devices according to
specific installation sites that might not conform to the standard extrapolation value, which could lead to
cost savings and reduced interference potential.
In addition, we clarify that parties testing BPL equipment and systems for compliance with
emissions limits in our rules should measure at the standard reference 30-meter distance whenever
possible, and only measure at the shorter distances recommended in the BPL measurement guidelines if
safety or ambient conditions require taking measurements at a closer distance such as 10 meters or 3
meters from the overhead line. We also adopt a definition for the slant-range distance used in the BPL
measurement guidelines to further clarify its application. We also modify our BPL measurement
guidelines to provide clarity for those conducting measurements for compliance of Access BPL
equipment and systems with the Section 15.209 emissions standards by specifying the extrapolated values
of compliant emissions levels at 3-meter and 10-meter horizontal (lateral) distance from the nearest point
of the overhead power line carrying the BPL signals, for typical heights of medium voltage power lines.
These clarifications of the existing rules as well as the adoption of the definition for slant-range distance
would assist the industry in ensuring compliance of BPL systems, promoting possible cost savings
without imposing additional regulatory costs.

Report to Congress:

The Commission will send a copy of the Second Report and Order, including this
FRFA, in a report to be sent to Congress pursuant to the Congressional Review Act.17 In addition, the
Commission will send a copy of the Second Report and Order, including this FRFA, to the Chief Counsel for
Advocacy of the SBA. A copy of the Report and Order and FRFA (or summaries thereof) will also be
published in the Federal Register.18


17 See 5 U.S.C. 801(a)(1)(A).
18 See 5 U.S.C. 604(b).
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APPENDIX C

Final Rules

For the reasons discussed in the preamble, the Federal Communications Commission proposes to amend 47
C.F.R. Part 15 to read as follows:

PART 15 RADIO FREQUENCY DEVICES

1. The authority citation for part 15 continues to read as follows:

AUTHORITY:

47 U.S.C. 154, 302, 303, 304, 307 and 544A.
2. Section 15.3 is amended by adding paragraph (hh) to read as follows:
Section 15.3 Definitions.
* * * * *
(hh) Slant-Range Distance. Diagonal distance measured from the center of the measurement
antenna to the nearest point of the overhead power line carrying the Access BPL signal being measured.
This distance is equal to the hypotenuse of the right triangle as calculated in the formula below. The
slant-range distance shall be calculated as follows:
d
=
h
- h
+ d

slant
( pwr line ant )2
_
( h )2
Where:
dslant is the slant-range distance, in meters (see Figure 1, below);
dh is the horizontal (lateral) distance between the center of the measurement antenna and the
vertical projection of the overhead power line carrying the BPL signals down to the height of the
measurement antenna, in meters;
hpwr_line is the height of the power line, in meters; and
hant is the measurement antenna height, in meters.
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Figure 1 Illustration of Slant-Range Distance

D

slant
pwr_line

H

H

ant=1 m

D

h

D

limit=30 m
(For F<30 MHz)
Dslant is the slant-range distance, in meters;
Dh is the horizontal (lateral) distance between the center of the measurement antenna and the
vertical projection of the overhead power line carrying the BPL signals down to the height of the
measurement antenna, in meters;
Dlimit is the distance at which the emission limit is specified in Part 15 (e.g., 30 meters for
frequencies below 30 MHz);
Hpwr_line is the height of the power line, in meters; and
Hant is the measurement antenna height, in meters.
3. Section 15.31 is amended by revising paragraph (f)(2) to add a sentence at the end of this paragraph,
by re-designating paragraphs (f)(3) through (f)(5) as (f)(4) through (f)(6), and by adding a new
paragraph (f)(3), to read as follows:
Section 15.31 Measurement standards.
* * * * *
(f) * * *
* * * * *
(2) * * * This paragraph shall not apply to Access BPL devices operating below 30
MHz.
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(3) For Access BPL devices operating below 30 MHz, measurements shall be performed
at the 30-meter reference distance specified in the regulations whenever possible. Measurements may be
performed at a distance closer than that specified in the regulations if circumstances such as high ambient
noise levels or geographic limitations are present. When performing measurements at a distance which is
closer than specified, the field strength results shall be extrapolated to the specified distance by using the
square of an inverse linear distance extrapolation factor (i.e., 40 dB/decade) in conjunction with the
slant-range distance defined in Section 15.3(hh) of this part. As an alternative, a site-specific
extrapolation factor derived from a straight line best fit of measurements of field strength in dBV/m vs.
logarithmic distance in meters for each carrier frequency, as determined by a linear least squares
regression calculation from measurements for at least four distances from the power line, may be used.
Compliance measurements for Access BPL and the use of site-specific extrapolation factors shall be made
in accordance with the Measurement Guidelines for Access BPL systems specified by the Commission.
Site-specific determination of the distance extrapolation factor shall not be used at locations where a
ground conductor is present within 30 meters if the Access BPL signals are on the neutral/grounded line
of a power system.
* * * * *
4. Section 15.37 is amended by adding paragraph (o) to read as follows:
Section 15.37 Transition provisions for compliance with the rules.
* * * * *
(o) All Access BPL devices operating below 30 MHz that are manufactured, imported, marketed
or installed on or after [insert date 18 months from date of publication in the Federal Register] shall
comply with the requirements specified in Section 15.611(c)(1)(i) of this part.
5. Section 15.611 is amended by revising paragraph (c)(1) (i) to read as follows:
Section 15.611 General technical requirements.
* * * * *
(c) * * *
(1) * * *
(i) For frequencies below 30 MHz, when a notch filter is used to avoid
interference to a specific frequency band, the Access BPL system shall be capable of attenuating
emissions within that band to a level at least 25 dB below the applicable Part 15 limits.
* * * * *
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APPENDIX D

Measurement Guidelines for Broadband Over Power Line (BPL) Devices Or Carrier Current

Systems (CCS) and Certification Requirements For Access BPL Devices

This appendix is intended to provide general guidance for compliance measurements of
Broadband over power line (BPL) devices and other carrier current systems (CCS). For BPL systems, the
measurement principles are based on the Commission's current understanding of BPL technology.
Modifications may be necessary as measurement experience is gained.
1. General Measurement Principles for Access BPL, In-House BPL and CCS
1) Testing shall be performed with the power settings of the Equipment Under Test (EUT) set at the
maximum level.
2) Testing shall be performed using the maximum RF injection duty factor (burst rate). Test modes or
test software may be used for uplink and downlink transmissions.
3) Measurements should be made at a test site where the ambient signal level is 6 dB below the
applicable limit. (See ANSI C63.4-2003, section 5.1.2 for alternatives, if this test condition cannot be
achieved.)
4) If the data communications burst rate is at least 20 burst per second, quasi-peak measurements shall
be employed, as specified in Section 15.35(a) of the rules. If the data communications burst rate is 20
bursts per second or less, measurements shall be made using a peak detector.
5) For frequencies above 30 MHz, an electric field sensing antenna, such as a biconical antenna is used.
The signal shall be maximized for antenna heights from 1 to 4 meters, for both horizontal and vertical
polarizations, in accordance to ANSI C63.4-2003 procedures. For Access BPL measurements only,
as an alternative to varying antenna height from 1 to 4 meters, these measurements may be made at a
height of 1 meter provided that the measured field strength values are increased by a factor of 5 dB to
account for height effects.
6) For frequencies below 30 MHz, an active or passive magnetic loop is used. The magnetic loop
antenna should be at 1 meter height with its plane oriented vertically and the emission maximized by
rotating the antenna 180 degrees about its vertical axis. When using active magnetic loops, care
should be taken to prevent ambient signals from overloading the spectrum analyzer or antenna pre-
amplifier.
7) The six highest radiated emissions relative to the limit and independent of antenna polarization shall
be reported as stated in ANSI C63.4-2003, section 10.1.8.2.
8) All operational modes should be tested including all frequency bands of operation, as required by
Section 15.31(i) of the rules.
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2. Access BPL Measurement Principles
a. Test Environment
1) The Equipment Under Test (EUT) includes all BPL electronic devices e.g., couplers, injectors,
extractors, repeaters, boosters, concentrators, and electric utility overhead or underground medium
voltage lines.

2) In-situ testing shall be performed on three typical installations for overhead line(s) and three typical
installations for underground line(s).
b. Radiated Emissions Measurement Principles for Access BPL on Overhead Line

Installations

1) Measurements should normally be performed at the horizontal reference distance as specified in
Sections 15.209 and 15.109 of the rules (i.e., 30 meters for frequencies below 30 MHz and 10 meters
for frequencies 30-88 MHz.) If necessary, due to ambient emissions, for frequencies below 30 MHz,
measurements may be performed at a closer distance such as 10 meters (or 3 meters if necessary for
safety or because measurements cannot practically be performed at 30 meters or 10 meters) from the
overhead line. Distance corrections are to be made in accordance with paragraph (4), below.
2) Testing shall be performed at distances of 0, , , , and 1 wavelength down the line from the BPL
injection point on the power line. Wavelength spacing is based on the mid-band frequency used by
the EUT. In addition, if the mid-band frequency exceeds the lowest frequency injected onto the
power line by more than a factor of two, testing shall be extended in steps of wavelength of the
mid-band frequency until the distance equals or exceeds wavelength of the lowest frequency
injected. (For example, if the device injects frequencies from 3 to 27 MHz, the wavelength
corresponding to the mid-band frequency of 15 MHz is 20 meters, and wavelength corresponding to
the lowest injected frequency is 100 meters. Measurements are to be performed at 0, 5, 10, 15, and
20 meters down line--corresponding to zero to one wavelength at the mid-band frequency. Because
the mid-band frequency exceeds the minimum frequency by more than a factor of two, additional
measurements are required at 10-meter intervals until the distance down-line from the injection point
equals or exceeds of 100 meters. Thus, additional measurement points are required at 30, 40, and
50 meters down line from the injection point.)
3) Testing shall be repeated for each Access BPL component (injector, extractor, repeater, booster,
concentrator, etc.)
4) The distance correction used to calculate the applicable extrapolated emission levels for the
measurements that are closer than the specified reference distance in Section 15.209 of the rules shall
be based on the slant-range distance, which is the diagonal distance from the center of the
measurement antenna to the nearest point of the overhead power line carrying the BPL signals being
measured, as defined in Section 15.3(hh) of the rules. Calculations of the slant-range distance and the
applicable extrapolated emission levels are made according to Equations (1) and (2) in Section 6,
below.
5) For Access BPL devices operating below 30 MHz, if the site-specific alternative extrapolation
method is selected, the extrapolation factor is determined by fitting a straight line to measurements of
field strength in dBV/m vs. logarithmic distance in meters from the nearest conductor carrying BPL
emissions. Site-specific determination of the extrapolation factor is not permitted for BPL devices
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that inject signals on the neutral/grounded line of a power system if a grounding conductor (typically
located at each pole) is located within 30 meters of any of the measurement locations.
a. Measurements shall be made for at least four horizontal distances from the overhead line, at no
less than 3 meters from the lateral plane and differing from each other by at least 3 meters. If
these measurements allow a straight line with a negative slope to be calculated or drawn with
reasonable fit (the minimum regression coefficient of multiple correlation would be 0.9), the best
straight line fit would be used to calculate field strength at the 30-meter standard measurement
distance in the rules.
b. If the four measurements do not satisfy the regression coefficient requirement specified above,
measurements at one or more additional distances shall be added until the regression coefficient is
satisfied. If the regression coefficient is not satisfied, a site-specific extrapolation rate may not be
used.
Note: In cases where Access BPL devices are coupled to low-voltage power lines (i.e., In-House BPL or
modem boosters), apply the overhead-line procedures as stated above along the low-voltage power lines.
c. Radiated Emissions Measurement Principles for Access BPL in Underground Line

Installations

1) Underground line installations are those in which the BPL device is mounted in, or attached to a pad-
mounted transformer housing or a ground-mounted junction box and couples directly only to
underground cables.
2) Measurements should normally be performed at the horizontal reference distance as specified in
Section 15.209 of the rules (i.e., 30 meters for frequencies below 30 MHz and 10 meters for
frequencies 30-88 MHz.) If necessary, due to ambient emissions, for frequencies below 30 MHz,
measurements may be performed at a closer distance such as 3 meters or 10 meters from the in-
ground transformer. Distance corrections are to be made in accordance with Section 15.31(f) in the
rules.
3) Measurements shall be made at positions around the perimeter of the in-ground power transformer
where the maximum emissions occur. ANSI C63.4-2003, section 8.1, specifies a minimum of 16
radial angles surrounding the EUT (in-ground transformer that contains the BPL device(s)). If
directional radiation patterns are suspected, additional azimuth angles shall be examined.
d. Conducted Emissions Measurement Principles
Conducted emissions testing is not required for Access BPL.
3. In-House BPL and Carrier Current Systems Measurement Principles
1) In-House BPL devices are typically composite devices consisting of two equipment classes (Carrier
current system and personal computer peripheral (Class B)). While carrier current systems require
Verification, personal computer peripherals require Declaration of Conformity (DoC) or Certification,
as specified in Section 15.101 of the Rules. Appropriate tests to determine compliance with these
requirements shall be performed.
2) In-situ testing is required for testing of the carrier current system functions of the In-House BPL
device.
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3) If applicable, the device shall also be tested in a laboratory environment, as a computer peripheral, for
both radiated and conducted emissions tests per the measurement procedures in C63.4-2003.
a. Test Environment and Radiated Emissions Measurement Principles for In-House BPL
and CCS In-Situ Testing
1) The Equipment under Test (EUT) includes In-House BPL modems used to transmit and receive
carrier BPL signals on low-voltage lines, associated computer interface devices, building wiring, and
overhead or underground lines that connect to the electric utilities.
2) In-situ testing shall be performed with the EUT installed in a building on an outside wall on the
ground floor or first floor. Testing shall be performed on three typical installations. The three
installations shall include a combination of buildings with overhead-line(s) and underground line(s).
The buildings shall not have aluminum or other metal siding, or shielded wiring (e.g.: wiring installed
through conduit, or BX electric cable).
3) Measurements shall be made at positions around the building perimeter where the maximum
emissions occur. ANSI C63.4-2003, section 8.1, specifies a minimum of 16 radial angles
surrounding the EUT (building perimeter). If directional radiation patterns are suspected, additional
azimuth angles shall be examined.
4) Measurements should normally be performed at the horizontal reference distance as specified in
Sections 15.209 and 15.109 of the rules (i.e., 30 meters for frequencies below 30 MHz and 3 meters
for frequencies 30-88 MHz.) If necessary, due to ambient emissions, for frequencies below 30 MHz,
measurements may be performed at a closer distance such as 3 meters or 10 meters around the
building perimeter as outlined in step 3) above. Distance corrections are to be made in accordance
with Section 15.31(f) of the Rules.
b. Additional Measurement Principles for In-House BPL and CCS In-Situ Testing With

Overhead Lines

1) In addition to testing radials around the building, testing shall be performed at three positions along
the overhead line connecting to the building (i.e. the service wire). It is recommended that these
measurements be performed starting at a distance 10 meters down the line from the connection to the
building. If this test cannot be performed due to insufficient length of the service wire, a statement
explaining the situation and test configuration shall be included in the technical report.
2) Measurements should normally be performed at the horizontal reference distance as specified in
Sections 15.209 and 15.109 of the rules (i.e., 30 meters for frequencies below 30 MHz and 10 meters
for frequencies 30-88 MHz.) Measurements may then be performed at a closer distance such as 3
meters or 10 meters from the overhead line. Distance corrections are to be made in accordance with
paragraph 2.b.4 above.
c. Measurement Principles for Testing In-House BPL and CCS as a Computer Peripheral
1) The data rate shall be set at the maximum rate used by the EUT. Test modes or test software may be
used to simulate data traffic.
2) For In-House BPL devices operating as unintentional radiators below 30 MHz, the conducted
emissions shall be measured in the 535 1705 kHz band as specified in Section 15.107(c). For In-
House BPL devices operating as unintentional radiators above 30 MHz, the conducted emissions shall
64

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FCC 11-160

be measured as specified in Section 15.107(a). Conducted emissions measurements shall be
performed in accordance with ANSI C63.4-2003 (Section 7 and Annex E).
3) For In-House BPL devices operating as unintentional radiators either below 30 MHz or above 30
MHz, the radiated emissions limits of Section 15.109(a) apply. The radiated emissions from the
computer peripheral shall be measured at an Open Area Test Site (OATS) in accordance with the
measurement procedures in C63.4-2003 (Section 8 and Annex D)
4. Certification Technical Report Requirements for Access BPL Devices
1) Certification applications shall be accompanied by a technical report in accordance with Section
2.1033 of the Rules. Each device used in an Access BPL system requires its own Certification.
2) For Access BPL devices, the statement describing how each device operates shall include the
following information: modulation type, number of carriers, carrier spacing, channel bandwidth,
notch capability/control, power settings/control, and range of signal injection duty factors.
3) For Access BPL devices, the measurement report shall include representative emissions spectrum
plot(s) of the reported data.
4) For Access BPL devices operating below 30 MHz, if the site-specific method for determining the
extrapolation factor was used, the measurement report shall include detailed information on the
calculations and the data points taken.
5. Responsibility of BPL operator
It is recommended that a BPL operator perform initial installation and periodic testing of Access BPL
systems on his power lines. These tests shall be performed to ensure that the system in conjunction with
the installation site complies with the appropriate emission limits using the measurement procedures
outlined in Section 3 of this document. The BPL operator should use typical installation sites within his
service area as outlined in section 2(a) of this document. Selection of typical sites shall be made
according to the characteristics of the installation as a whole. The BPL operator is not required to submit
the test results. In the instance that the Access BPL system was tested on the operator's network for
certification purposes, the initial installation tests do not need to be repeated. However, periodic testing
of installed Access BPL systems is recommended to ensure that the system maintains compliance with
Part 15 emission limits.
6. Calculation of Slant-Range Distance and Extrapolated Emission Level for Access BPL
operating on overhead power lines
Figure 1 shows an example of the testing configuration of Access BPL devices operating below 30 MHz
on overhead power line installations. It is provided to illustrate the calculation of extrapolated emission
levels using the slant range method when the device cannot be tested at the required reference distance of
30 meters specified in the rules. As explained below, when making emission measurements at a distance
closer than 30 meters, the measured result must be extrapolated to the Part 15 specified measurement
distance (i.e., 30 meters) to determine compliance with the Part 15 emission limit, because the radiated
emission limit for Access BPL devices operating below 30 MHz is only specified at the reference distance
of 30 meters.
65

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Figure 1 Testing configuration of Access BPL devices operating below 30 MHz

D

slant
pwr_line

H

H

ant=1 m

D

h

D

limit=30 m
(For F<30 MHz)
Dslant is the slant-range distance, in meters;
Dh is the horizontal (lateral) distance between the center of the measurement antenna and the
vertical projection of the overhead power line carrying the BPL signals down to the height of the
measurement antenna, in meters;
Dlimit is the distance at which the emission limit is specified in Part 15 (e.g., 30 meters for
frequencies below 30 MHz)
Hpwr_line is the height of the power line, in meters; and
Hant is the measurement antenna height, in meters.
66

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a. Slant-Range Distance Formula
The slant-range distance is calculated using the following formula:
d
=
h
- h
+ d

(Equation 1)
slant
( pwr line ant )2
_
( h )2
Where:
dslant is the slant-range distance, in meters;
dh is the horizontal (lateral) distance between the center of the measurement antenna and the
vertical projection of the overhead power line carrying the BPL signals down to the height of the
measurement antenna, in meters;
hpwr_line is the height of the power line, in meters; and
hant is the measurement antenna height, in meters.
b. Extrapolated Emission Level Formula
Because the radiated emission limit for Access BPL devices operating below 30 MHz is specified at the
reference distance of 30 meters, when making emission measurements at a distance closer than 30 meters,
the measured result must be extrapolated to the specified measurement distance (i.e., 30 meters) to
determine compliance with the Part 15 emission limit. The extrapolated emission level (in dBV/m) is
calculated using the following formula:
d

E
= E
- N
limit
Log
(Equation 2)
extrap
meas
10


dslant
Where:
N is the distance extrapolation factor, e.g., 40 for frequencies below 30 MHz;
dlimit is the horizontal measurement distance corresponding to the Part 15 emissions limits, e.g., 30
meters for frequencies below 30 MHz;
dslant is the slant-range distance, in meters;
Emeas is the measured electric field strength at a horizontal distance, dh, in dBV/m; and
Eextrap is the electric field strength value after applying the distance extrapolation factor, in dBV/m
If the extrapolated electric field strength value exceeds the Part 15 emission limit (i.e. 29.54 dBV/m for
Access BPL operating below 30 MHz as specified for a horizontal measurement distance of 30 meters),
the Access BPL device must lower its emission level to comply with the limit.
c. Extrapolated Emission Levels For Access BPL Devices Installed on Typical Overhead

Power Line Heights

The tables below show examples of extrapolated maximum allowable emission levels for Access BPL
devices installed on typical overhead power line heights (10-12 meters in the United States). If the power
line height involved is different than the illustrated heights below, the slant-range distance and applicable
extrapolated emission level must be calculated using Equations 1 and 2, above.
67

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Table 1 - Power Line Height of 10 m

Frequency
Horizontal
Power Line
Calculated
Extrapolated Radiated
(MHz)
Distance from
Height (meter)
Slant-Range
Emission Maximum
nearest point of
Distance (meter)
Allowable Level
overhead power
(dBV/m)
line carrying
the BPL signals
(meter)
1.705-30
3
10
9.49
49.54
1.705-30
10
10
13.45
43.47

Table 2 - Power Line Height of 11 m

Frequency
Horizontal
Power Line
Calculated
Extrapolated Radiated
(MHz)
Distance from
Height (meter)
Slant-Range
Emission Maximum
nearest point of
Distance (meter)
Allowable Level
overhead power
(dBV/m)
line carrying
the BPL signals
(meter)
1.705-30
3
11
10.44
47.88
1.705-30
10
11
14.14
42.60

Table 3 - Power Line Height of 12 m

Frequency
Horizontal
Power Line
Calculated
Extrapolated Radiated
(MHz)
Distance from
Height (meter)
Slant-Range
Emission Maximum
nearest point of
Distance (meter)
Allowable Level
overhead power
(dBV/m)
line carrying
the BPL signals
(meter)
1.705-30
3
12
11.40
46.35
1.705-30
10
12
14.87
41.74
68

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APPENDIX E

Extrapolated Emission Maximum Allowable Levels Using Slant-Range Method

With Various Power Line Heights

I.

SLANT-RANGE METHOD FOR MEASURING BPL EMISSIONS ON OVERHEAD
POWER LINES

The Commission adopted a slant-range method for measuring BPL emissions on overhead power lines in
Appendix C of the BPL Order. With the slant-range method, the distance correction for the overhead-line
measurements of Access BPL emissions is based on the slant-range distance, which is the diagonal
distance from the center of the measurement loop antenna to the overhead power line, illustrated in Figure
1 of the amended Measurement Guidelines, supra. Slant-range distances are calculated based on the
height of the power line and the horizontal (lateral) distance (Dh) between the center of the measurement
antenna and the vertical projection of the overhead power line carrying the BPL signals down to the
height of the measurement antenna (see Equation 1, below). Slant-range distance corrections are made in
accordance with Section 15.31(f)(3) (e.g., using 40 dB/decade extrapolation factor for frequencies below
30 MHz).

II.

EXTRAPOLATED LEVELS COMPARISONS WITH TYPICAL POWER LINE
HEIGHTS

Typical medium-voltage power line heights in the United States are 10-12 meters. Figures 1-3 below
illustrate a comparison between the extrapolated emission levels with respect to horizontal (lateral)
distance when using extrapolation factors of 40 dB (trace 1), 20 dB (trace 2) and when using the
Commission's slant-range method calculated using 40 dB/decade extrapolation factor (trace 3).
As illustrated, the resulting extrapolated maximum allowable emission level applied to Access BPL
devices is more stringent than for other Part 15 devices operating below 30 MHz by virtue of using the
slant-range distance in the calculation of extrapolated emission levels. This extrapolated maximum
allowable level is very close (within a 5 dB range for typical medium-voltage power line heights) to what
ARRL is requesting, i.e., using 20 dB/decade extrapolation factor with straight horizontal (lateral)
distance.

A.

Extrapolated Levels using 40 dB/decade and Slant-range distance From a Power
Line Height of 10 meters

Figure 1 illustrates a comparison between the extrapolated maximum allowable emission levels with
respect to horizontal (lateral) distance when using extrapolation factors of 40 dB/decade (trace 1), 20
dB/decade (trace 2) and when using the Commission's slant-range distance method calculated with 40
dB/decade extrapolation factor (trace 3). Calculations are made according to Equations 1 and 2 below,
using a power line height of 10 meters. This results in a measurement height of 9 meters, because the
measurement loop antenna is at 1 meter from the ground.
69

Federal Communications Commission

FCC 11-160

Figure 1 Extrapolated Levels Comparison with 40 dB/decade Extrapolation Factor Applied to

Slant-Range Distance Power Line Height at 10 meters

Extrapolated Levels Comparison - Power Line Height = 10m

100
90
(1)
80
70
(1) 40 dB
(2)
60
(2) 20 dB
50
(3)
40
(3) Slant
30
Extrapolated Level (dBV/m)
20
10
0
0
5
10
15
20
25
30
Horizontal Distance (m)
As illustrated in Figure 1 for power line heights of 10 meters, the Commission's slant-range method using
a 40 dB/decade extrapolation factor applied to slant-range distance provides an extrapolated emission
level graph that reveals the following.

At measurement distances greater than 5 meters, the extrapolated maximum allowable
emission levels for slant-range distance based on the existing 40 dB/decade factor (trace
3) are LESS stringent than extrapolated emission levels based on 20 dB/decade
extrapolation factor for horizontal (lateral) distance (trace 2), by a maximum of 4.4 dB.
This maximum difference between the two traces (trace 2 and trace 3) is found at a
horizontal distance of 9 meters from the nearest point of the overhead power pole
carrying the BPL signals.

At these same measurement distances (greater than 5 meters), the extrapolated maximum
allowable emission levels for slant-range distance based on the existing 40 dB/decade
factor (trace 3) are MORE stringent than extrapolated emission levels based on 40
dB/decade extrapolation factor for horizontal (lateral) distance (trace 1), by as much as
12.6 dB.

However, at measurement distances less than 5 meters, the extrapolated maximum
allowable emission levels for slant-range distance based on the existing 40 dB/decade
factor (trace 3) are MORE stringent than extrapolated emission levels for horizontal
(lateral) distance based on either 20 dB/decade (trace 2) or 40 dB/decade extrapolation
factor (trace 1).
70

Federal Communications Commission

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B.

Extrapolated Levels using 40 dB/decade and Slant-range distance From a Power
Line Height of 11 meters

Figure 2 illustrates a comparison between the extrapolated maximum allowable emission levels with
respect to horizontal (lateral) distance when using extrapolation factors of 40 dB/decade (trace 1), 20
dB/decade (trace 2) and when using the Commission's slant-range distance method calculated with 40
dB/decade extrapolation factor (trace 3). Calculations are made according to Equations 1 and 2 below,
using a power line height of 11 meters. This results in a measurement height of 10 meters, because the
measurement loop antenna is at 1 meter from the ground.

Figure 2 Extrapolated Levels Comparison with 40 dB/decade Extrapolation Factor Applied to

Slant-Range Distance Power Line Height at 11 meters

Extrapolated Levels Comparison - Power Line Height = 11m

100
90
(1)
80
70
(1) 40 dB
(2)
60
(2) 20 dB
50
(3)
40
(3) Slant
30
Extrapolated Level (dBV/m)
20
10
0
0
5
10
15
20
25
30
Horizontal Distance (m)
As illustrated in Figure 2 for power line heights of 11 meters, the Commission's slant-range method using
a 40 dB/decade extrapolation factor applied to slant-range distance provides an extrapolated emission
level graph that reveals the following.

At measurement distances greater than 5 meters, the extrapolated maximum allowable
emission levels for slant-range distance based on the existing 40 dB/decade factor (trace
3) are LESS stringent than extrapolated emission levels based on 20 dB/decade
extrapolation factor for horizontal (lateral) distance (trace 2), by a maximum of 3.5 dB.
This maximum difference between the two traces (trace 2 and trace 3) is found at a
horizontal distance of 10 meters from the nearest point of the overhead power line
carrying the BPL signals.

At these same measurement distances (greater than 5 meters), the extrapolated maximum
allowable emission levels for slant-range distance based on the existing 40 dB/decade
factor (trace 3) are MORE stringent than extrapolated emission levels based on 40
71

Federal Communications Commission

FCC 11-160

dB/decade extrapolation factor for horizontal (lateral) distance (trace 1), by as much as
14 dB.

However, at measurement distances less than 5 meters, the extrapolated maximum
allowable emission levels for slant-range distance based on the existing 40 dB/decade
factor (trace 3) are MORE stringent than extrapolated emission levels for horizontal
(lateral) distance based on either 20 dB/decade (trace 2) or 40 dB/decade extrapolation
factor (trace 1).

C.

Extrapolated levels using 40 dB/decade in conjunction with slant-range distance
from a power line height of 12 meters

Figure 3 illustrates a comparison between the extrapolated maximum allowable emission levels with
respect to horizontal (lateral) distance when using extrapolation factors of 40 dB (trace 1), 20 dB (trace 2)
and when using the Commission's slant-range distance method calculated with 40 dB per decade
extrapolation factor (trace 3). Calculations are made according to Equations 1 and 2 below, using a
power line height of 12 meters. This results in a measurement height of 11 meters, because the
measurement loop antenna is at 1 meter from the ground.

Figure 3 Extrapolated Levels Comparison with 40 dB/decade Extrapolation Factor Applied to

Slant-Range Distance Power Line Height at 12 meters

Extrapolated Levels Comparison - Power Line Height = 12m

100
90
(1)
80
70
(1) 40 dB
(2)
60
(2) 20 dB
50
(3)
40
(3) Slant
30
Extrapolated Level (dBV/m)
20
10
0
0
5
10
15
20
25
30
Horizontal Distance (m)
72

Federal Communications Commission

FCC 11-160

As illustrated in Figure 3 for power line heights of 12 meters, the Commission's measurement method
using a 40 dB/decade extrapolation factor applied to slant-range distance provides an extrapolated
emission level graph that reveals the following.


At measurement distances greater than 5 meters, the extrapolated maximum allowable
emission levels for slant-range distance based on the existing 40 dB/decade factor (trace
3) are LESS stringent than extrapolated emission levels based on 20 dB/decade
extrapolation factor for horizontal (lateral) distance (trace 2), by a maximum of 2.7 dB.
This maximum difference between the two traces (trace 2 and trace 3) is found at a
horizontal distance of 10 meters from the nearest point of the overhead power line
carrying the BPL signals.

At these same measurement distances (greater than 5 meters), the extrapolated maximum
allowable emission levels for slant-range distance based on the existing 40 dB/decade
factor (trace 3) are MORE stringent than extrapolated emission levels based on 40
dB/decade extrapolation factor for horizontal (lateral) distance (trace 1), by as much as
15.3 dB.

However, at measurement distances less than 5 meters, the extrapolated maximum
allowable emission levels for slant-range distance based on the existing 40 dB/decade
factor (trace 3) are MORE stringent than extrapolated emission levels for horizontal
(lateral) distance based on either 20 dB/decade (trace 2) or 40 dB/decade extrapolation
factor (trace 1).

III.

SLANT-RANGE DISTANCE CALCULATION FORMULA

The slant-range distance is calculated using the following formula:1
d
=
h
- h
+ d

(Equation 1)
slant
( pwr line ant )2
_
( h )2
Where:
dslant is the slant-range distance, in meters;
dh is the horizontal (lateral) distance between the center of the measurement antenna and the
vertical projection of the overhead power line carrying the BPL signals down to the height of the
measurement antenna, in meters;
hpwr_line is the height of the power line, in meters; and
hant is the measurement antenna height, in meters.

IV.

EXTRAPOLATED EMISSION LEVEL CALCULATION FORMULA

The extrapolated emission level (in dBV/m) is calculated using the following formula:2


1 See NTIA Phase 2 Study, supra at Section 2.5.1.
2 Id.
73

Federal Communications Commission

FCC 11-160

d

E
= E
- N
limit
Log
(Equation 2)
extrap
meas
10


dslant
Where:
N is the distance extrapolation factor, e.g., 40 for frequencies below 30 MHz;
dlimit is the horizontal measurement distance corresponding to the Part 15 emissions limits, e.g,. 30
meters for frequencies below 30 MHz;
dslant is the slantrange distance, in meters;
Emeas is the measured electric field strength at a horizontal distance, dh, in dBV/m; and
Eextrap is the electric field strength value after applying the distance extrapolation factor, in dBV/m
If the extrapolated electric field strength value exceeds the Part 15 emission limit (i.e. 29.54 dBV/m for
Access BPL operating below 30 MHz as specified for a horizontal measurement distance of 30 meters),
the Access BPL device must lower its emission level to comply with the limit.
74

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APPENDIX F

List of Additional Materials Included in the Record

Index of BPL Files

Summary of Presentations Including HomePlug Emissions and Noise Near Power Lines

File Name

Title and Date

Description

Index of BPL Files.doc
"Index of BPL Files",
Index of BPL files
4/16/2009
Field Strength Measurements
"Field Strength Measurements
Presentation including
Relative to ARRL Concerns
Relative to ARRL Concerns
measurements of ambient spectrum
Regarding BPL-
Regarding BPL", 10/16/2003
levels near residential power lines
wEmbeddedDate.ppt
and of access BPL emissions
BPL--FccLab to OET 12-03-
"Broadband Over Power Line
Presentation including
2003a-wEmbeddedDate.ppt
(BPL) Test Results and
measurements of ambient spectrum
Considerations", 12/3/2003
levels near power lines,
measurements of access BPL
emissions, and tests of in-house
BPL interference to reception on
portable shortwave radio and on
fixed amateur HF antenna
(spectrum levels and embedded
audio)**
BPL & Ambient Noise7.xls
Spreadsheet
Supporting Data: Raw data and
plots of ambient noise
measurements near power lines and
of access BPL emissions--used in
"Field Strength Measurements
Relative to ARRL Concerns
Regarding BPL" and "Broadband
Over Power Line (BPL) Test
Results and Considerations"
HomePlug Test In Gary
Spreadsheet
Supporting Data: Raw data and
Hendrickson neighborhood.xls
plots of ambient and HomePlug-
generated spectrum levels measured
on an HF amateur antenna--used in
"Broadband Over Power Line
(BPL) Test Results and
Considerations"
** Should be played in Power Point slide show mode due to embedded audio. See file at
http://www.fcc.gov/oet/info/bpl/.
75

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Raleigh Test Results (Amperion)

File Name

Title and Date

Description

BPL Test in Raleigh_V-AM-
"BPL Interference Test Near
MPEG4 video files documenting
S1.mp4
Raleigh, NC--July 1, 2004"
BPL sounds observed at two fixed
BPL Test in Raleigh_V-SSB-
sites (S1 and S2) as a radio receiver
S1.mp4
operating in either AM or SSB
BPL Test in Raleigh_V-AM-
mode was tuned across spectrum
S2.mp4
used by BPL system
BPL Test in Raleigh_V-SSB-
S2.mp4
BPL Test in Raleigh_V-AM-

No title
MPEG4 video file documenting
D2.mp4
reception of a shortwave radio
broadcast while driving toward
overhead power lines carrying BPL
signals
Briarcliff Manor Test Results (Ambient)

File Name

Title and Date

Description

Briarcliff Test Report-2004final-
"BPL Emission Tests
Presentation documenting
wEmbeddedDate.ppt
In Briarcliff Manor,
Briarcliff Manor tests of an
NY, August 17 - 19,
access BPL system
2004"
Briarcliff Manor BPL Video Files-L01a.doc
"Briarcliff Manor BPL
Description of video files of
Video Files"
driving tests from Briarcliff
Manor
BriarcliffVid1_320x240x15-300kbps-
"BPL Interference
MPEG4 video files
32kbps.mp4
Test--Briarcliff Manor, documenting interference to
BriarcliffVid2_320x240x15-300kbps-
NY--August 17-19,
reception of simulated radio
32kbps.mp4
2004"
transmissions during driving
BriarcliffVid3_320x240x15-300kbps-
tests.
32kbps.mp4
BriarcliffVid4_320x240x15-300kbps-

Files with names containing
32kbps.mp4
"_320x240x15-300kbps-
BriarcliffVid5_320x240x15-300kbps-
32kbps" are medium-resolution
32kbps.mp4
videos. Files with names
BriarcliffVid6_320x240x15-300kbps-
containing "_640x480x30-
32kbps.mp,
3800kbps-32kbps" are high-
BriarcliffVid5_640x480x30-3800kbps-
resolution files (videos 5 and 6
32kbps.mp4
only)
BriarcliffVid6_640x480x30-3800kbps-
32kbps.mp4
BriarcliffLevelVsGPSCoord16.xls

Spreadsheet
Supporting data: GPS
coordinates and received levels
during driving tests in Briarcliff
Manor
76

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