For radio stations, especially AM stations, HF means more headaches every day. Radio frequency or RF interference has grown along with the number of electronic devices on the market. Now the Federal Communications Commission is taking the first steps to address RF concerns. Because the ability to reduce the sources of this conclusion is limited, the FCC is focusing for the first time on the standards that receiver manufacturers rely on.
The Commission voted in April to launch a process to explore options to encourage improvements in RF receiver performance. While FCC frequency management efforts have often focused on broadcaster regulations, the Notice of Inquiry (ET File No. 22-137) takes a fresh look at the role of receivers and how improved receiver performance can drive more efficient use of spectrum. The commission says its goal in this process is to lay the groundwork for future actions that could help create a more transparent and predictable radio spectrum environment for all spectrum users, including radio stations. Ideas being explored include the use of incentives, industry-led voluntary approaches, and regulatory requirements. It also examines the Commission’s legal authority for various approaches it might consider.
“The era of rich spectrum is coming to an end. As with real estate, they just don’t do anything with it anymore. The future is dense spectral neighborhoods of commercial users, densely packed in space and spectrum, vying for every last hertz of usable real estate,” said Commissioner Nathan Simington, who has led the FCC’s RF control efforts. “We should think of the RF spectrum as a fully occupied country whose use must inevitably be intensified. Our regulatory philosophy must reflect this new reality,” he said.
Moving forward in the process, Xperi – the licensor of HD Radio and DTS AutoStage technology – is asking the FCC to focus on preserving existing spectrum usages and established users such as radio stations. In comments filed with the agency, the company also penalized the FCC for failing to mention the potential effects of increasing the noise floor, particularly in the AM band.
Xperi also warns that inference is likely to become a bigger problem for FM. Both bands suffer from increasing levels of interference, mainly caused by inexpensive switching power supplies found in most consumer electronics devices. “While this type of noise has historically been prevalent in the AM band, new sources of unintended radiation are now threatening both AM and FM quality of service,” the FCC said.
A fix may already be in hand. Xperi says digital radio’s In-Band On-Channel (IBOC) technology offers a “significant level of interference immunity” and it believes things will improve as more stations switch to digital operations. Xperi proposes that the FCC adopt a minimum product requirement for car and portable AM/FM radios to include digital radio capabilities to “ensure continued efficient use of the AM/FM band and the services they provide.”
At the same time, Xperi says that a one-size-fits-all approach should not be used. “The receivers used for aeronautical radars and satellites, for example, bear little resemblance to the receivers used for broadcast services or personal communications devices,” it says.
What about satellite radio receivers?
From satellites stationed more than 22,000 miles in space, SiriusXM transmits signals to more than 130 million moving vehicles with teacup-sized antennas and other wearable and mobile devices. Given the potential for RF interference similar to AM/FM, she agrees that the FCC should not use general mandates.
“Voluntary approaches represent the best path forward,” says SiriusXM, noting that all of its investments in receiver performance are driven by market incentives. “SiriusXM operates in a highly competitive audio market and must continually evolve and improve its approach to receiver design and performance to meet demand and provide the best possible audio experience for its listeners,” it said.
As the Commission moves forward, SiriusXM believes the FCC should use “reasonable” receiver performance metrics that reflect industry standards and technical realities. The company also says that one of the FCC’s guiding principles should be that services already licensed should expect protection from new entrants.
The RF investigation is still in its early stages and where the commission goes will depend in part on the feedback it receives from the various industries. But FCC Chair Jessica Rosenworcel said both receivers and transmitters must be part of the response.
“It’s a two-sided offer. Both are vital. Both are important,” she said. “There is too little in our existing spectrum policy that recognizes this truth. There is also too little incentive for users or manufacturers to invest in better quality receivers.”