Thursday, May 31, 2007

FCC releases IBOC rules

The FCC has released the permanent IBOC rules.

Read the original FCC document on these links:



  • Microsoft Word

  • Adobe Acrobat

  • Text



  • 30 days after publication in the Federal Register, IBOC digital radio ("HD Radio") will cease to be something authorized through Special Temporary Authority and become a normal part of American radio. The biggest difference listeners (and especially DXers) will notice is that AM stations will be allowed to operate their HD signals at night.

    The highlights, as the Commission puts them:



  • Refrains from imposing a mandatory conversion schedule for radio stations to commence digital broadcast operations;

  • Allows FM radio stations to operate in the extended hybrid digital mode;

  • Requires that each local radio station broadcasting in digital mode provide a free over-the-air digital signal at least comparable in audio quality to its analog signal;

  • Continues to require that the main digital broadcast stream simulcast the material aired on the analog signal;

  • Adopts a flexible bandwidth policy permitting a radio station to transmit high quality audio, multiple program streams, and datacasting services at its discretion;

  • Allows radio stations to time broker unused digital bandwidth to third parties, subject to certain regulatory requirements;

  • Applies existing programming and operational statutory and regulatory requirements to all free DAB programming streams, but defers the issue of whether and how to apply any specific new public interest requirements;

  • Authorizes AM nighttime operations and FM dual antenna configurations;

  • Considers and addresses other technical matters, such as FM translator and booster operations and TV Channel 6 interference issues;

  • Defers discussion of whether the Commission should impose content control requirements that would prevent listeners from archiving and redistributing digital musical recordings transmitted by digital broadcast stations;

  • Recognizes that further negotiations between the United States and the international community are taking place to resolve possible disputes about the implementation and operation of DAB by domestic radio stations;

  • Dismisses several pending Petitions for Reconsideration and Petitions for Rulemaking that asked, inter alia, the Commission to reconsider the adoption of iBiquity’s IBOC system as the technology chosen for DAB transmission;

  • Seeks further comment on appropriate limits to the amount of subscription services that may be offered by radio stations.



  • A few notes of my own:



  • The FCC mentions authority for "extended hybrid mode" on FM stations. This mode adds more digital capacity by adding digital carriers. However, these carriers fall between the digital carriers authorized in "normal" hybrid mode, and the station's analog signal. So if extended hybrid mode is going to cause interference (and it might), the interference will be to the station's own analog signal, not to other stations'.

  • LPFM and translator stations will be allowed to adopt IBOC. It's stated that IBOC operation may not be practical for LP10 (10-watt LPFM) stations.

  • Legal ID announcements will be required on all program streams, and digital multicast streams must be identified as such. "WZMF-2 Menomonee Falls" may not be legal - "WZMF Digital HD2 Menomonee Falls" might be. A "text ID" using the Program Associated Data may be adequate.

  • AM stations that have already notified the FCC of their daytime use of IBOC need not perform further notification to begin nighttime operation.

  • Comments were filed in an attempt to get the FCC to limit the IBOC power of "superpower" FM stations to what would be authorized to a "normal" station. For example, WOOD-FM in Grand Rapids, Mich. is authorized for 265kw analog power at 177m HAAT. IBOC digital power is regulated as a percentage of analog; in WOOD's case it would be allowed to run 2,650 watts of digital power. If WOOD wasn't grandfathered in at its pre-1964 power, it would be limited to 35,909 watts analog power, or 359 watts digital. The Commission dismissed this attempt; WOOD will get its 2,650 watts of digital power.

  • The U.S. is still in negotiations with Canada and Mexico. (A Canadian engineer and DXer filed comments arguing that IBOC is prohibited under bilateral treaties with both countries.) IBOC permits will contain a clause noting that they may be modified or revoked if international considerations require it.

  • Strangely enough, all of this was accomplished by creating only four new rules (47CFR73.401..73.404) and amending one. (47CFR73.1201, the station identification rule)



  • Going back to the international considerations...



    Canadian commenter Barry McLarnon quotes an article in the US-Canada agreement that states: "
    “Classes of emission other than A3E, for instance to accommodate stereophonic systems, could also be used on condition that the energy level outside the necessary bandwidth does not exceed that normally expected in A3E....”

    McLarnon argues that the IBOC digital carriers extend the station's bandwith to approximately 28KHz, far outside that necessary and normally expected from an A3E (regular analog AM) signal. He also notes that an identical clause exists in the US-Mexico agreement.

    Editorial comment: Barry is 100% right.
    Editorial comment: But since when does the U.S. government listen to any other country when there's money to be made?

    1 comment:

    Doug Smith said...

    An article in Radio World Online reports that the Mexican government is considering allowing IBOC operation by stations within 320km (200mi.) of the U.S. border. The article says there are 80 such FM stations and 120 AMs.