Goto Section: 73.403 | 73.501 | Table of Contents
Revised as of October 20, 2020
Goto Year:2020 |
§ 73.404 Interim hybrid IBOC DAB operation.
(a) The licensee of an AM or FM station, or the permittee of a new AM
or FM station which has commenced program test operation pursuant to
§ 73.1620, may commence interim hybrid IBOC DAB operation with digital
facilities which conform to the technical specifications specified for
hybrid DAB operation in the First Report and Order in MM Docket No.
99-325, as revised in the Media Bureau's subsequent Order in MM Docket
No. 99-325. FM stations are permitted to operate with hybrid digital
effective radiated power equal to one percent (−20 decibels below
carrier (dBc)) of authorized analog effective radiated power and may
operate with up to ten percent (−10 dBc) of authorized analog effective
radiated power in accordance with the procedures set forth in the Media
Bureau's Order in MM Docket No. 99-325. An AM or FM station may
transmit IBOC signals during all hours for which the station is
licensed to broadcast.
(b) In situations where interference to other stations is anticipated
or actually occurs, AM licensees may, upon notification to the
Commission, reduce the power of the primary DAB sidebands by up to 6
dB. Any greater reduction of sideband power requires prior authority
from the Commission via the filing of a request for special temporary
authority or an informal letter request for modification of license.
(c) Hybrid IBOC AM stations must use the same licensed main or
auxiliary antenna to transmit the analog and digital signals.
(d) FM stations may transmit hybrid IBOC signals in combined mode;
i.e., using the same antenna for the analog and digital signals; or may
employ separate analog and digital antennas. Where separate antennas
are used, the digital antenna:
(1) Must be a licensed auxiliary antenna of the station;
(2) Must be located within 3 seconds latitude and longitude from the
(3) Must have a radiation center height above average terrain between
70 and 100 percent of the height above average terrain of the analog
(e) Licensees must provide notification to the Commission in
Washington, DC, within 10 days of commencing IBOC digital operation.
The notification must include the following information:
(1) Call sign and facility identification number of the station;
(2) Date on which IBOC operation commenced;
(3) Certification that the IBOC DAB facilities conform to permissible
(4) Name and telephone number of a technical representative the
Commission can call in the event of interference;
(5) FM digital effective radiated power used and certification that the
FM analog effective radiated power remains as authorized;
(6) Transmitter power output; if separate analog and digital
transmitters are used, the power output for each transmitter;
(7) If applicable, any reduction in an AM station's primary digital
(8) If applicable, the geographic coordinates, elevation data, and
license file number of the auxiliary antenna employed by an FM station
as a separate digital antenna;
(9) If applicable, for FM systems employing interleaved antenna bays, a
certification that adequate filtering and/or isolation equipment has
been installed to prevent spurious emissions in excess of the limits
specified in § 73.317;
(10) Licensees and permittees shall ensure compliance with the
Commission's radio frequency exposure requirements in § 1.1307(b) of
this chapter. An Environmental Assessment may be required if RF
radiation from the proposed facilities would, in combination with
radiation from other sources, cause RF power density or field strength
in an accessible area to exceed the applicable limits specified in
§ 1.1310 of this chapter.
[ 72 FR 45692 , Aug. 15, 2007, as amended at 75 FR 17877 , Apr. 8, 2010;
85 FR 18151 , Apr. 1, 2020]
Subpart D—Noncommercial Educational FM Broadcast Stations
Source: 28 FR 13651 , Dec. 14, 1963, unless otherwise noted.
Redesignated at 72 FR 45692 , Aug. 15, 2007.
Goto Section: 73.403 | 73.501
Goto Year: 2020 |
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