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WTB Seeks Comment on Harmful Interference

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Released: October 26, 2011


Federal Communications Commission

News Media Information 202 / 418-0500

445 12th St., S.W.


Washington, D.C. 20554

TTY: 1-888-835-5322

DA 11-1790

Released: October 26, 2011




WT Docket No. 11-178

Comment Date: November 25, 2011
Reply Comment Date: December 12, 2011

The Wireless Telecommunications Bureau (Bureau) seeks comment on a request for clarification
filed by Icom, America, Inc. (Icom).1 Icom seeks clarification of the Commission's regulations regarding
trunking in the bands between 150 and 512 MHz, specifically Section 90.187(b) of the Commission's
Rules, which 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."2 Icom
seeks guidance as to whether "a 250 millisecond data burst from a control channel idle message [would]
represent harmful interference."3 It states, "Given that its data burst would not impact the analog signal
and be barely discernable white noise, Icom hopes that the Commission will find that the data burst is not
harmful interference."4 In response to a request from Bureau staff, Icom provided the following technical
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 ms. 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

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 August 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 See id.
5 See Supplement at 1-2.

We seek comment on Icom's request. Commenters should 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). If a blanket response is suitable, commenters should address
whether the Commission should consider a 250 millisecond data burst from a control channel idle
message as described by Icom to be harmful interference for purposes of Section 90.187(b). Further, we
seek comment as to whether such operations should be permitted on Public Safety Pool frequencies.6 .

Procedural matters

Comments on the request are due no later than November 25, 2011. Reply comments are due
no later than December 12, 2011. All filings should reference the docket number of this proceeding WT
This proceeding has been designated as a "permit-but-disclose" proceeding in accordance with the
Commission's ex parte rules.7 Parties making oral ex parte presentations in this proceeding are reminded
that memoranda summarizing the presentation must contain the presentation's substance and not merely list
the subjects discussed.8 More than a one- or two-sentence description of the views and arguments presented
is generally required.9
The request, and comments and reply comments filed in response to this Public Notice, will be
available for public inspection and copying in the Commission's Reference Center, Room CY-A257, 445
12th Street, S.W., Washington, D.C. 20554, and via the Commission's Electronic Comment Filing System
(ECFS) by entering the docket number, WT 11-178. Copies of the request are also available from Best
Copy and Printing, Inc., telephone (800) 378-3160, facsimile (301) 816-0169, e-mail
Comments may be filed using the ECFS or by filing paper copies. See Electronic Filing of
Documents in Rulemaking Proceedings, 63 Fed. Reg. 24121 (1998). Comments filed through the ECFS can
be sent as an electronic file via the Internet to Generally, only one copy of an
electronic submission must be filed. If multiple docket or rulemaking numbers appear in the caption of this
proceeding, however, commenters must transmit one electronic copy of the comments to each docket or
rulemaking number referenced in the caption. In completing the transmittal screen, commenters should
include their full name, U.S. Postal Service mailing address, and the applicable docket or rulemaking
number. Parties may also submit an electronic comment by Internet e-mail. To get filing instructions for e-
mail comments, commenters should send an e-mail to , and should include the following
words in the body of the message, "get form." A sample form and directions will be sent in reply.
Parties who choose to file by paper must file an original and one copy of each filing. If more than
one docket or rulemaking number appears in the caption of this proceeding, commenters must submit two

6 Cf. Amendment of Part 90 of the Commission's Rules to Permit Terrestrial Trunked Radio (TETRA) Technology,
Notice of Proposed Rule Making and Order, WT Docket No. 11-69, 26 FCC Rcd 6503, 6510-11 22 (2011)
(granting waiver to permit use of Terrestrial Trunked Radio equipment on certain Industrial/Business Pool spectrum,
but not on Public Safety Pool frequencies due to increased concerns about interference).
7 See 47 C.F.R. 1.1200(a), 1.1206.
8 See Commission Emphasizes the Public's Responsibilities in Permit-But-Disclose Proceedings, Public Notice, 15
FCC Rcd 19945 (2000).
9 See 47 C.F.R. 1.1206(b)(2). Other rules pertaining to oral and written presentations are also set forth in Section
1.1206(b). See 47 C.F.R. 1.1206(b).

additional copies for each additional docket or rulemaking number.
Filings can be sent by hand or messenger delivery, by commercial overnight courier, or by first-
class or overnight U.S. Postal Service mail (although we continue to experience delays in receiving U.S.
Postal Service mail). All filings must be addressed to the Commission's Secretary, Office of the Secretary,
Federal Communications Commission, as follows:
-All hand-delivered paper filings for the Commission's Secretary must be delivered to FCC
Headquarters at 445 12th St., S.W., Room TW-A325, Washington, DC 20554. All hand deliveries must be
held together with rubber bands or fasteners. Envelopes must be disposed of before entering the building.
The filing hours at this location are 8:00 a.m. to 7:00 p.m.


This is the


where hand-delivered or messenger-delivered paper filings for the Commission's Secretary will be
accepted. The Commission's former filing location at 236 Massachusetts Ave., N.E., is permanently closed.
-Commercial overnight mail (other than U.S. Postal Service Express Mail and Priority Mail) must
be sent to 9300 East Hampton Drive, Capitol Heights, MD 20743.
-U.S. Postal Service first-class mail, Express Mail, and Priority Mail should be addressed to 445
12th Street, S.W., Washington, DC 20554.
-All filings must be addressed to the Commission's Secretary, Office of the Secretary, Federal
Communications Commission.
Parties are requested to send one copy of their comments and reply comments to Best Copy and
Printing, Inc., Portals II, 445 12th Street, S.W., Room CY-B402, Washington, D.C. 20554, (800) 378-3160,
Alternate formats of this Public Notice (computer diskette, large print, audio recording, and
Braille) are available to persons with disabilities by contacting the Consumer & Governmental Affairs
Bureau at (202) 418-0530 (voice), (202) 418-0432 (TTY), or send an e-mail to
For further information, contact Mr. Melvin Spann of the Mobility Division, Wireless
Telecommunications Bureau at (202) 418-1333 or via e-mail to
Action by the Deputy Chief, Mobility Division, Wireless Telecommunications Bureau.
- FCC -

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