The authoritative news source for communications regulation
Interference Concerns?

Broadcasters Support NAB and XPeri Digital FM Petitions

Broadcasters largely support a proposal to allow higher digital FM power levels, though some are cautious about possible interference, according to comments posted last week in docket 22-405 on a petition for rulemaking from NAB and Xperi (see 2210270061). The petition asked the agency to amend its rules on in-band/on-channel (IBOC) digital audio broadcasting to adopt an updated formula to determine digital FM power levels for stations. “Comprehensive interference protection for existing, incumbent analog stations must be adopted as part of any potential rule changes to digital FM power levels,” said broadcaster Howard Toole. Commenters also supported a 2019 request from NAB, Xperi and NPR to permanently authorize FM radio stations to utilize IBOC with asymmetric sideband power levels.

Start A Trial

Granting the petitions will “improve the signal quality and coverage” of digital FM stations “without adverse impact to other FM licensees,” said broadcaster CMG Media. “Consumers today have a vast number of options to choose from when listening to audio content, but most of those options are by subscription or other cost to the consumer.” The proposed formula “better reflects the real-world interference environment in the FM band and the appropriate level of protection that 1st-adjacent stations need from harmful interference,” said Beasley Media. The changes would create a better listening experience for HD radio users “thus maintaining the relevance of radio in a manner that is in the public interest,” said LPFM group REC Networks.

Eliminating the need to apply for experimental authorizations for asymmetrical sideband operations will save both FCC and broadcaster resources and allow more stations to take advantage of improved coverage,” said Glynn Walden, founder of the USA Digital Radio/iBiquity Digital Corporation IBOC Radio System. The FCC should extend the updated interference formula to grandfathered, super-powered stations “so that all full power FM station licensees are treated equally,” said Communications Technologies, a broadcast engineering consulting firm.

NPR and other broadcast commenters said the agency should take precautions to prevent interference from the heightened power levels. “NPR supports the Petition so long as any new rules adopted protect the existing operations of incumbent stations,” it said. The FCC should require licensees increasing their power levels to notify adjacent stations first, NPR said. “While NPR agrees interference may be unlikely, without notice, if interference does occur, it could be difficult for the affected licensee to track down the source.” The FCC should adopt procedures for gauging possible interference as part of any rulemaking on the matter, said broadcast engineering firm Cohen Dippel.

One group particularly concerned with possible interference is the International Association of Audio Information Services, a volunteer organization that broadcasts readings of newspapers, magazines “and other programs of interest to blind, visually impaired, physically disabled and other print-disabled persons.” IAAIS broadcasts often use FM subcarriers, secondary audio channels that can be picked up with special receivers. The group wants the FCC to require stations hosting or adjacent to subcarrier hosts to notify them of planned power increases. “Unfortunately, NAB and Xperi have neglected to fully consider the needs of existing services, such as FM sub-carrier users,” said IAAIS. “It is unclear to us why this is? It could be the expense of additional testing, a calculation that the risk is low, and/or they simply forgot to consider our needs.”