HD radio interference

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Until recently, to many in the industry, HD radio seemed to be an afterthought – maybe useful in feeding analog translators, but otherwise not very accessible to the public.  But there is now more and more interest in HD radio given the increased inclusion of receivers for this digital service as standard equipment in a majority of new cars.  This means that consumers have ready access to programming on digital FM subchannels that the technology allows, plus the digital sound quality that HD radio provides and the auxiliary data services that can be conveyed along with the audio programming.  This week, the FCC’s Media Bureau issued a Public Notice asking for comments on two technical proposals to enhance service to the public while minimizing interference that the service might otherwise cause to nearby adjacent-channel stations.

Comments are sought on a proposal by the National Association of Broadcasters and Xperi, Inc. (which acquired iBiquity, the company that developed the HD Radio technology) seeking adoption of an updated formula for computing the power level of the “sidebands” on which the HD service resides. The request also asks that the proposal be combined with a 2019 request that FM stations be allowed to operate an HD service with “asymmetric sidebands” without having to seek experimental authority.  What do these requests mean and why might they be important?
Continue Reading FCC Seeks Comments on HD Radio Technical Standards – Could a Power Increase for Digital FM Radio Be Coming?

Last month, the FCC released a Public Notice requesting further comments on the proposal to increase the power of HD radio operations.  We have written about that proceeding a number of times, including posts here and here.  The increased power for the digital radio signals has been sought by many broadcasters who believe that current HD radio power levels do not  produce strong enough digital signals to penetrate buildings and fully serve radio markets.  On the other hand, other broadcasters fear that the increased power for the digital signals will create interference to existing analog stations operating on adjacent channels.  Today, the FCC set the dates for the filing of these additional comments – comments are due on July 6, with replies due on July 17. 

While comments have already been filed on the proposal to increase digital power, the FCC has raised a number of specific issues on which it wants comments, especially in light of the studies sponsored by NPR in cooperation with a number of other broadcasters, which seek to do a comprehensive review of the interference potential of higher powered digital operations.  NPR is shooting to have that report to the FCC in September.  The specific questions raised in the new FCC notice are:

  • Whether the FCC should wait to decide on the power increase proposal until after the NPR study is done
  • Whether current operations by radio stations operating in HD, and the various tests that have already been run, demonstrate the need for higher power operation on a permanent or provisional basis
  • Whether new standards of interference to adjacent channel stations should be adopted, and if the interference should also protect LPFM stations
  • Whether there should be specific procedures adopted to resolve any interference issues that do arise. 

Continue Reading FCC Seeks More Comments on Possible HD Radio Power Increase – Should LPFM Be Protected?