COMMENT SOUGHT ON REQUEST FOR FM ASYMMETRIC SIDEBAND OPERATION
Federal Communications Commission
News Media Information 202 / 418-0500
Internet: https://www.fcc.gov445 12th St., S.W.
Washington, D.C. 20554
November 1, 2011
MM Docket No. 99-325
COMMENT SOUGHT ON REQUEST
FOR FM ASYMMETRIC SIDEBAND OPERATION
AND ASSOCIATED TECHNICAL STUDIES
Comment Date: [21 days after date of publication in the Federal Register]
Reply Comment Date: [35 days after date of publication in the Federal Register]
the pending digital audio broadcasting proceeding, MM Docket No. 99-325,1 and establishes deadlines for
filing these comments.
On October 4, 2011, representatives of iBiquity Digital Corporation ("iBiquity") and National Public
Radio, Inc. ("NPR") met with Bureau staff to discuss the possibility of permitting FM stations to operate
with unequal digital sideband power levels. Concurrently with the submission of its ex parte meeting
notice, iBiquity filed a technical report which discusses the field performance of asymmetric digital
sideband operation by FM stations. Based on the report, iBiquity and NPR requested that the
Commission authorize voluntary asymmetric digital sideband power for FM stations. Subsequently, on
October 24, 2011, NPR filed a report which describes the results of field testing of asymmetric FM digital
sidebands used in conjunction with testing of a newly-developed technology for reducing the peak-to-
average power ratio in digital transmitters. The NPR Report concludes: "In sum, broadcasters are best off
maintaining symmetrical sideband levels, but coverage improvements are possible with an increase of
only one sideband."2
The iBiquity and NPR technical reports are available electronically from the FCC's Electronic Comment
Filing System under MM Docket No. 99-325, at
http://fjallfoss.fcc.gov/ecfs/document/view?id=7021717638 , respectively; or from the Commission's
duplicating contractor, Best Copy and Printing, Inc. ("BCPI"), 445 12th Street, SW, Room CY-B402,
Washington, DC, 20554, 1-800-378-3160.
1 See Digital Audio Broadcasting Systems and Their Impact on the Terrestrial Radio Broadcast Service, Second
Report and Order, First Order on Reconsideration and Second Further Notice of Proposed Rulemaking, 22 FCC Rcd
10,344 (2007) (prior history omitted).
2 NPR Report, page 8.
Currently, FM stations may operate only with equal power levels on the upper and lower primary digital
sidebands. In the First IBOC Order,3 the Commission authorized FM stations to commence hybrid
digital broadcasting with digital effective radiated power of one percent (-20 dBc4) of the analog carrier
level. In authorizing in-band on-channel ("IBOC") operation for FM stations, the Commission observed:
"The digital portion of the hybrid IBOC signal is transmitted on frequencies immediately adjacent to the
main analog signal. Consequently, minimizing interference to stations on first- and, to a lesser extent,
second-adjacent channels poses the most serious analog compatibility challenge. The [National Radio
Systems Committee] concluded that 'listeners within the protected contour [of the first-adjacent analog
station] should not perceive an impact, but a limited number of listeners may perceive an impact outside
of the protected contour under certain conditions.'"5
Early experience with FM IBOC operation, however, showed the one-percent digital power level to be
insufficient to replicate analog coverage areas. In response to a request from a group of broadcasters, the
Bureau issued its January 29, 2010, Order,6 which authorized most FM stations to increase their digital
power up to 6 dB (to -14 dBc) upon notification to the Commission, and some stations up to 10 dB (to -
10dBc) by filing an informal application which demonstrates that certain contour non-overlap conditions
are met with respect to other stations operating on the upper and lower first-adjacent channels.
A significant number of FM stations currently are precluded from taking advantage of the full 10 dB
digital power increase permitted by the Order due to the presence of a nearby station on one but not both
of the two first-adjacent channels. If asymmetric digital sideband operation is permitted, such stations
presumably could increase their digital power on the sideband away from the limiting station. The two
technical reports include data supporting iBiquity's and NPR's contention that such operations may
improve a station's digital coverage without causing interference.
By this notice, comment is sought on the iBiquity/NPR request and the iBiquity and NPR reports. We
tentatively conclude that it would be expedient to modify Form FCC 335-FM, currently used for Digital
Notifications, to accommodate requests for increased digital power and/or operation with asymmetric
digital sideband power. Thus, we also seek comment on the process by which FM stations engaging in
such operations would notify the Commission and how such notifications would be maintained in the
Commission's electronic databases.
Interested parties may submit comments on or before 21 days after the date of publication of a summary
of this Public Notice in the Federal Register, and reply comments on or before 35 days after date of
publication of this Public Notice in the Federal Register. Comments and reply comments should
specifically reference this Public Notice and MM Docket No. 99-325, and must be submitted in MM
Docket No. 99-325. Pleadings sent via e-mail to the Commission will be considered informal and will
not be part of the official record.
3 Digital Audio Broadcasting Systems and Their Impact on the Terrestrial Radio Broadcast Service, First Report and
Order, 17 FCC Rcd 19990 (2002) ("First IBOC Order").
4 Decibels relative to analog carrier.
5 First IBOC Order, at 19995.
6 Digital Audio Broadcasting Systems and Their Impact on the Terrestrial Radio Broadcast Service, Order, 25 FCC
Rcd 1182 (MB 2010) ("Order").
Comments may be filed using: (1) the Commission's Electronic Comment Filing System (ECFS), (2) the
Federal Government's eRulemaking Portal, or (3) paper copies.7
Electronic Filers: Comments may be filed electronically using the Internet by accessing the ECFS:
https://www.fcc.gov/cgb/ecfs/ or the Federal eRulemaking Portal: http://www.regulations.gov. Filers
should follow the instructions provided on the website for submitting comments.
For ECFS filers, in completing the transmittal screen, filers should include their full name, U.S. Postal
service mailing address, and the applicable docket number: MM Docket No. 99-325. Parties may also
submit an electronic comment by Internet e-mail. To get filing instructions, filers should send an e-mail
to email@example.com, and include the following words in the body of the message: "get form". A sample form
and instructions will be sent in response.
Paper Filers: Parties who choose to file by paper must file an original and four copies of each filing.
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.
The Commission's contractor will receive hand-delivered or messenger-delivered paper filings for the
Commission's Secretary at 236 Massachusetts Avenue, NE, Suite 110, Washington, D.C. 20002. The
filing hours at this location are 8:00 a.m. to 7:00 p.m. All hand deliveries must be held together with
rubber bands or fasteners. Any envelopes must be disposed of before entering the building.
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, SW, Washington, D.C. 20554.
Ex parte status:This is a "permit-but-disclose" rulemaking proceeding for purposes of the
Commission's ex parte rules. See generally 47 C.F.R. 1.1200-1.1216. As a result of the permit-but-
disclose status of this proceeding, ex parte presentations will be governed by the procedures set forth in
Section 1.1206 of the Commission's rules applicable to non-restricted proceedings.8
Copies of the reports and any subsequently filed documents in this matter may be obtained electronically
at https://www.fcc.gov/e-file/ecfs.html, and in paper form from BCPI during normal business hours in the
Commission's Reference Information Center located at 445 12th Street, SW, Room CY-A257,
Washington, DC, 20554. Alternate formats of this Public Notice (computer diskette, large print, audio
recording, or Braille) are available to persons with disabilities by contacting the Consumer and
Governmental Affairs Bureau at (202) 418-0530 or (202) 418-7365 (TTY).
For additional information, contact Susan Crawford, Peter Doyle, Ann Gallagher, or Charles Miller of the
Audio Division at (202) 418-2700.
By: Chief, Media Bureau-FCC-
7 See Electronic Filing of Documents in Rulemaking Proceedings, Report and Order, 13 FCC Rcd 11322, 11326
(1998) ( 8).
8 See 47 C.F.R. 1.1206.
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