White Spaces Proposal Threatens Public Safety, APCO Says

Comments are due today (Tues.) and many parties are expected to file in opposition to the FCC proposal. However, Edmond Thomas, chief of the FCC Office of Engineering & Technology, has said in recent speeches he continues to believe that the TV “white spaces” can be safely used for wireless Internet and other unlicensed users.

APCO noted in its filing that some of the largest U.S. public safety agencies use the band, which includes channels 14-20, for their principal portable and mobile systems. The include the N.Y. Police Dept., the L.A. Police Dept. and the L.A. County Sheriff’s Dept., plus 11 other major localities’ agencies. APCO told the FCC the controls proposed are inadequate and would lead to “destructive interference” with public safety. “While the Commission proposes technological controls on the areas in which such devices can operate, the required technology is untested in a real world environment,” APCO said: “Public safety cannot be a ‘guinea pig’ for this spectrum sharing technology.”

L.A. County also filed comments opposing unlicensed use of the channels, citing public safety considerations. The county called on the FCC to instead test other channels first. “Once initiated, and once various location restrictions are proven effective, then and only then should the Commission consider allowing unlicensed operations on channels 14-20,” the county said.

Among other early comments, the Wireless Internet Service Providers Assn. encouraged the FCC to proceed with opening the unused TV channels to unlicensed users. “Operations in the TV channel spectrum below 700 MHz will allow users to access the unlicensed signals regardless of the amount of arboreal foliage along a transmission path,” the group said. “The impact of universal coverage on small, rural, economically deprived communities will be measurable.”

Pikes Peak Bcstg. told the FCC it should use the Longley-Rice Terrain Dependent analysis when determining interference of unlicensed devices in the TV broadcast band. TV engineers believe prediction of interference using F(50,50) curves is inaccurate, Pikes Peak said in comments. Pikes Peak engineers calculated predicted coverage for its full service TV stations and several UHF translators comparing the Grade B and 74 dBu contours by applying both F(50,50) and the Longley-Rice analysis. It found that “real world” coverage extends well beyond Grade B of the full service stations and the predicted 74 dBu contour of the UHF translators. If a fixed intentional radiator were allowed within the Grade B or 74 dBu contour of a translator, “significant” interference would occur to both viewers and in many cases the input to the TV translator that relies upon the full service station’s input channel, it said. Pikes Peak said the same analysis would indicate interference to its assigned DTV channels, which might result in complete loss of a signal. Pikes Peak asked the FCC to delay the proceeding until uncertainties of the digital transition, including the realignment of the TV band channels, are resolved. Pikes Peak also suggested that the Commission require licensing or registration of these devices in recognition of interference risks.

Metropolitan Area Networks said a Common Signaling Mode (CSM) would allow unlicensed devices to use the spectrum without creating interference. CSM involves a wireless interface, provided through beacon transmissions, providing a spectrum etiquette that alerts unlicensed devices as to what spectrum can be used and what must be avoided: “The Commission’s proposal can result in optimized spectrum usage provided that the Commission requires the use of technologies, such as CSM, that will protect current broadcast television transmissions.”