NAB, MSTV Warn FCC About “White Space” Interference

The National Association of Broadcasters and the Association for Maximum Service Television have told the FCC that white space proponents have failed to provide proof that using a portion of broadcasters’ spectrum for unlicensed devices would not interfere with broadcast signals.

In reply comments filed with the commission this week, the two lobbying organizations were responding to the FCC Office of Engineering and Technology Laboratory’s report Interference Rejection Thresholds of Consumer Digital Television Receivers Available in 2005 and 2006. NAB and MSTV criticized the Device Coalition’s attempts to use the report to show unlicensed white space devices would not cause interference to DTV receivers. The Device Coalition is a consortium of consumer electronics and computer companies that support using unused space in the broadcast spectrum, i.e. white spaces for unlicensed devices.

“While the Device Coalition attempts to use the Commission’s Report to support its position that harmful interference will not occur, it fails to cite to any data or findings within the Report. At no point throughout this process has the Device Coalition presented the Commission with any research to counter the studies submitted by MSTV and NAB, and now the Commission, proving that harmful interference will occur.”

NAB and MSTV also used the reply comments to criticize the devices Device Coalition submitted for testing, stating, “these devices are not representative of the TV band devices which would be introduced into the market. Consequently, these devices cannot form a basis upon which to craft rules capable of protecting the public’s television service from the actual devices intended for the TV band.”

After explaining that the data from the FCC Report “clearly shows that a 100 mW transmitter operating on the first adjacent channel could cause interference to DTV viewers in 80 to 87 percent of a TV station’s service area depending on which of the Commission’s tested DTV receivers is used,” MSTV and NAB listed the steps the FCC must take to address the concerns discussed in the Report.

MSTV and NAB said that, at minimum, the FCC must prohibit TV band devices from operating on co- or adjacent channels, that it must establish proper desired to undesired (D/U) ratios, and that it must prohibit operation of all personal/portable devices within the television broadcast spectrum.

“The stakes in this proceeding are particularly high as the country is undergoing an expensive and important transition to DTV technology,” the two organizations noted in their comments. “It is integral that the Commission protect the billions of dollars invested in this transition.”

Broadcasters are not the only ones submitting reply comments concerning the OET report.

Samsung Electronics said, “Even very low-power emissions from personal/portable devices operating within broadcasters’ service area in locations where the signal is relatively weak could potentially prevent the reception of broadcast DTV signals. The FCC Report is a valuable first step, but significantly more testing is necessary before the Commission should permit unlicensed uses of the white spaces by personal/portable devices.”

Samsung cautioned, “As mobile services become a growing part of U.S. DTV broadcasting, protection of DTV reception from interference will be even more important than today.”

LG Electronics, which recently introduced its MPH technology in competition to Samsung’s A-VSB technology for delivering programming to mobile, portable and handheld devices echoed Samsung’s concerns and issued an even sterner warning:

“It would be sadly ironic if, after all these efforts by the private and public sectors to educate consumers and to promote a successful conclusion to the transition, the Commission were to allow new devices to prevent consumers from reaping the benefits of that transition. Moreover, the Commission should not allow new devices to preclude the public’s enjoyment of new DTV innovations, many of which are already in advanced stages of development.”

LG noted that it was not possible to predict the proximity of unlicensed transmitters to consumer portable DTVs and other mobile devices.

All of the comments and reply comments in this proceeding are available using the Search for Filed Comments web site. Enter “04-186” in box 1, which is labeled “Proceeding.”

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.