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Icom Data Burst Interference Interpretation Request Order

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Released: June 13, 2012

Federal Communications Commission

DA 12-925

Before the

Federal Communications Commission

Washington, D.C. 20554

In the Matter of

WT Docket No. 11-178
Request for Clarification of Section 90.187(b) of
the Commission’s Rules


Adopted: June 12, 2013

Released: June 13, 2013

By the Deputy Chief, Mobility Division, Wireless Telecommunications Bureau:
1. Introduction. We have before us a request from Icom America, Inc. (Icom) for clarification
of the Commission’s regulations regarding trunking in the bands between 150 and 512 MHz.1
Specifically, Icom seeks guidance as to whether a 250-millisecond data burst would constitute “harmful
interference” under Section 90.187(b) of the Commission’s Rules, which provides trunked systems must
provide a “level of monitoring . . . sufficient to avoid causing harmful interference to other systems.”2
For the reasons set forth below, we decline to provide the requested clarification.
2. Background. Icom requested clarification of whether a 250-millisecond data burst from a
control channel idle message would constitute harmful interference.3 It argued that the data burst should
not be considered harmful interference because it “would be barely discernable white noise.”4 In
response to a request from Wireless Telecommunications Bureau (Bureau) staff, Icom provided
additional technical information about the contemplated operations.5

1 See Letter dated August 17, 2011 from Alan S. Tilles to Rick Kaplan, Bureau Chief, Wireless
Telecommunications Bureau, Federal Communications Commission (Request); Letter dated September 29, 2011
from Alan S. Tilles to Rick Kaplan, Bureau Chief, Wireless Telecommunications Bureau, Federal Communications
Commission (Supplement).
2 47 C.F.R. § 90.187(b).
3 See Request at 1.
4 Id.
5 The data burst occurs every five seconds during idle time, but can be programmed to occur in the range of 3-10
seconds; the output power of the data burst is the same as the main transmitting signal; and each frame is 80
milliseconds. The “collect channel” (a channel that sends out a pulse for the roaming function) sends 6 frames, while
the “home channel” (which acts in a manner similar to a home channel in a traditional trunked Logic Trunked Radio
system) sends 4 frames. The frames include the site code, site overlap, and adjacent site information. See
Supplement at 1-2.

Federal Communications Commission

DA 12-925

3. The Bureau sought comment on Icom’s request.6 The Bureau asked commenters to address
whether a blanket response as requested by Icom is appropriate, or if, instead, the determination of
harmful interference requires a case-by-case analysis of each specific situation (such as the technical
parameters of the stations in question, and the distance and terrain between them). It also sought
comment as to, if a blanket response is suitable and a 250-millisecond data burst as described by Icom is
not deemed to be harmful interference for purposes of Section 90.187(b), whether such operations should
be permitted on Public Safety Pool frequencies.
The Bureau received four comments or reply comments. The Telecommunications Industry
Association (TIA) supported Icom’s request for a ruling that a 250-millisecond data burst does not
constitute harmful interference on Industrial/Business Pool frequencies, but argued that the question
should not be addressed with respect to Public Safety Pool frequencies without additional input from
manufacturers and the public safety community.7 Icom agreed with TIA.8 Two other commenters
opposed the request. Motorola Solutions (Motorola), Inc. argued that it would be inappropriate for the
Bureau to issue a broadly applicable definition of the definition of harmful interference based on the
detailed design parameters of one manufacturer’s technology, and that potential interference should be
evaluated on a case-by-case basis taking into account all relevant circumstances.9 The Land Mobile
Communications Council (LMCC) stated that Icom’s request should not be granted without additional
testing and input, but that whatever action ultimately is taken should apply equally to Industrial/Business
and Public Safety Pool frequencies.10
5. Discussion. Section 90.187(b) of the Commission’s Rules provides, “Trunked systems
operating under this section must employ equipment that prevents transmission on a trunked frequency if
a signal from another system is present on that frequency. The level of monitoring must be sufficient to
avoid causing harmful interference to other systems.”11 Under Section 90.7 of the Commission’s Rules
harmful interference is defined as “any emission, radiation, or induction which specifically degrades,
obstructs, or interrupts the service provided by such stations.”12
6. The Part 90 technical and service rules, except for those that govern only a specific class of
licensees, apply equally to all Part 90 licensees.13 Consequently, we agree with LMCC that Section

6 See Wireless Telecommunications Bureau Seeks Comment on Icom America, Inc. Request for Clarification of
Section 90.187(b) of the Commission’s Rules as to Whether a Data Burst Constitutes Harmful Interference, Public
, WT Docket No. 11-178, 26 FCC Rcd 15141 (WTB MD 2011).
7 See TIA Comments at 3-4.
8 See Icom Reply Comments at 1-2.
9 See Motorola Comments at 3.
10 See LMCC Reply Comments at 3-4.
11 47 C.F.R. § 90.187(b).
12 47 C.F.R. § 90.7.
13 See, e.g., Implementation of Sections 309(j) and 337 of the Communications Act of 1934 as Amended, Order,
WT Docket No. 99-87, 25 FCC Rcd 8861, 8863-64 ¶ 7 (2010) (applying waiver of narrowbanding rules equally to
Public Safety and Industrial/Business Pools); Amendment of Part 90 of the Commission’s Rules, Second Report
and Order and Second Further Notice of Proposed Rule Making
, WP Docket No. 07-100, 25 FCC Rcd 2479,
2487 § 22 (2010) (declining to split Part 90 into separate rule parts for different classes of licensees because
commenters believed that changing the organizational structure of Part 90 was “unnecessary and would likely

Federal Communications Commission

DA 12-925

90.187(b) should have the same meaning for Industrial/Business Pool licensees, Public Safety Pool
licensees, and Public Safety Pool eligibles operating on Industrial/Business Pool frequencies. In light of
our discretion as to whether or when to address requests for clarification or declaratory ruling,14 we
decline to issue a blanket response on the definition of harmful interference. Instead, the determination
of harmful interference shall continue to require a case-by-case analysis of each specific situation.
7. Accordingly, IT IS ORDERED that the request for clarification filed by Icom America, Inc.
on August 17, 2011 IS DENIED to the extent set forth above.
8. This action is taken under delegated authority pursuant to Sections 0.131 and 0.331 of the
Commission's Rules, 47 C.F.R. §§ 0.131, 0.331.
Scot Stone
Deputy Chief, Mobility Division
Wireless Telecommunications Bureau
(Continued from previous page)

result in a more complex regulatory burden being placed on Commission licensees without any likely benefit to the
licensees or the Commission”).
14 See, e.g., Feature Group IP, Order on Reconsideration, WC Docket No. 07-256, 25 FCC Rcd 8867, 8873 ¶ 10 &
n.40 (2010) (citing, e.g., Yale Broadcasting Co. v. FCC, 478 F.2d 594, 602 (D.C. Cir. 1973) (“An administrative
agency should not be compelled to issue a clarifying statement unless its failure to do so can be shown to be a clear
abuse of discretion.”)).

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