Reston, Va. - A government advisory board's tests that found LightSquared's planned 4G LTE network will interfere with GPS receivers of all types were "rigged to ensure that most receivers will fail," claimed LightSquared VP Jeff Carlisle.
The advisory board, called the Positioning, Navigation, and Timing Executive Committee (PNT EXCOM), advises the federal government on GPS issues, but the tests were actually conducted for it by the GPS industry, Carlisle said. GPS industry members "cherry-picked" the GPS receivers to be tested and focused the tests mainly on "obsolete and niche devices" that included discontinued GPS receivers and devices manufactured as far back as 1997, he charged. The tested devices were "ringers" and don't reflect devices on the market today, added LightSquared VP Geoff Stern.
On top of that, the advisory board's tests were based on LightSquared power outputs that are 32 times greater than what LightSquared actually plans, the company said. And the GPS industry defined failure by an arbitrary 1dB increase in the noise floor detected by GPS receivers even though today's GPS receivers are designed to tolerate a 6dB increase before a noticeable impact becomes apparent to GPS users, the company added. "The 1dB threshold can be detected only in a lab," and previous Federal Communications Commission (FCC)-mandated tests conducted by the GPS industry in partnership with LightSquared and federal agencies found that a 1dB increase in noise "didn't change accuracy," Carlise contended.
LightSquared called on the FCC and National Telecommunications and Information Administration (NTIA) to properly review the results and move forward quickly on LightSquared's proposal to use its satellite-band spectrum, which is next to the GPS band, for its planned terrestrial cellular-data network.
The NTIA has been analyzing the results of other tests mandated by the FCC and conducted by representatives of the federal government, GPS industry and LightSquared. Those tests were designed to gauge whether LightSquared's network would interfere with the operation of GPS receivers in cellphones, car navigation systems, and other consumer-oriented devices used for marine and outdoor recreation activities. The NTIA must also analyze the results of separate FCC-mandated tests planned for GPS receivers used for high-precision and timing applications. A start date for those tests hasn't been announced.
The Coalition to Save Our GPS, which represents GPS industry suppliers,
conducted to date found that LightSquared interfered with GPS in six of 39 cellphones and with 20 of 29 general location/navigation receivers. The group also cast doubt on the effectiveness of adding filters to these devices and high-precision GPS devices.