FCC Requests Comments on Draft Interference Rules

Last month I reported on SiriusXM CEO Mel Karmazin's concerns about interference from wireless communications services (WCS) in my article Broadband Expansion May Threaten Satellite Radio. Late last week the FCC Office of Engineering and Technology, the International Bureau and the Wireless Telecommunications Bureau issued a Public Notice seeking comment on the draft interference rules [PDF] and proposals for mobile operations in the WCS and on establishing rules for terrestrial repeaters operating in the Satellite Digital Audio Radio Service (SDARS).

The Public Notice notes that the draft rules include "numerous provisions to minimize the risk of harmful interference to SDARS."

As an example, they would create a 2.5 MHz guard band on each side of the SDARS spectrum where mobile WCS operations would not be allowed. The commission also noted that the draft rules would reduce WCS out-of-band emissions in steps to a level less than that of "nearly any other mobile devices." The peak-to-average power ratio and duty cycle of WCS transmitters would also be capped.

WCS licenses would have an obligation to correct any harmful interference to SDARS, even if the WCS transmitters meet all of the technical standards in the draft rules, although Karmazin's comments indicate that he doesn't see that provision effectively protecting SDARS.

The Aerospace and Flight Test Radio Coordinating Council (AFTRCC), which represents the interests of the aeronautical mobile telemetry service—which operates in spectrum immediately above the WCS band—is concerned that WCS mobile operations will interfere with reception of distant signals from aircraft undergoing flight tests and create safety risks. The FCC noted the draft rules put stringent limits on emissions into the aeronautical telemetry band and require coordination in areas near aeronautical telemetry receiver sites.

SiriusXM Radio will benefit from the draft rules, as they will allow blanket licensing of SDARS terrestrial repeaters that comply with the draft rules. Repeaters that don't comply with the draft rules wouldn't be prohibited, but they would be subject to site-by-site licensing.

As you've probably noticed in RF Report's "Satellite Update" section, SiriusXM Radio is currently operating all of its terrestrial repeaters under special temporary authority and has to request extension of that authority every six months. WCS users are concerned about interference from SDARS terrestrial repeaters.

The Public Notice states that while the draft rules do not adopt any party's proposal in full, "the staff believes that the proposed rules take a fair and balanced approach to facilitating mobile broadband operations in WCS band spectrum, which is largely unused today, while providing reasonable protection against harmful interference to incumbent services."

Doug Lung

Doug Lung is one of America's foremost authorities on broadcast RF technology. As vice president of Broadcast Technology for NBCUniversal Local, H. Douglas Lung leads NBC and Telemundo-owned stations’ RF and transmission affairs, including microwave, radars, satellite uplinks, and FCC technical filings. Beginning his career in 1976 at KSCI in Los Angeles, Lung has nearly 50 years of experience in broadcast television engineering. Beginning in 1985, he led the engineering department for what was to become the Telemundo network and station group, assisting in the design, construction and installation of the company’s broadcast and cable facilities. Other projects include work on the launch of Hawaii’s first UHF TV station, the rollout and testing of the ATSC mobile-handheld standard, and software development related to the incentive auction TV spectrum repack.
A longtime columnist for TV Technology, Doug is also a regular contributor to IEEE Broadcast Technology. He is the recipient of the 2023 NAB Television Engineering Award. He also received a Tech Leadership Award from TV Tech publisher Future plc in 2021 and is a member of the IEEE Broadcast Technology Society and the Society of Broadcast Engineers.