The GPS industry’s failure to comply with the Department of Defense’s receiver filtering standards is the root cause of potential interference issues involving LightSquared’s proposed broadband wireless network, the company has told the FCC. “Had the GPS industry complied with DOD’s recommended filtering standards for GPS receivers, there would be no issue with LightSquared’s operations in the lower portion of its downlink band,” it stated. The Coalition to Save Our GPS countered, “LightSquared has completely mischaracterized the 2008 DOD GPS signal in space standards, which according to DOD’s own language, define ‘the levels of performance the U.S. Government makes available to users of [GPS],’ but in no way addresses standards for commercial GPS receivers. In fact, DOD specifically said that the receiver characteristics it detailed ‘are not intended to impose any minimum requirements on receiver manufacturers or integrators,’ and they do not specify commercial GPS receiver performance standards.” Additionally, when the DOD wrote its standards in 2008, the adjacent L-band frequencies were specifically for very weak satellite signals, not for the transmission of signals from the likes of LightSquared that are a billion times more powerful. “There has never been, nor will there ever be, a filter that can block out signals one billion times more powerful than those transmitted in an immediately adjacent frequency,” the coalition concluded.
LightSquared: GPS Interference Is Manufacturers’ Fault
- August 16, 2011, 10:49 AM