Extensive testing by various government agencies, in cooperation with LightSquared, has shown their signal to interfere with GPS reception.
Although LightSquared statements in recent months have claimed the problems are solved, testimony in front of a US House Of Representatives sub-committee yesterday painted a different picture.
The problem stems from the location of the frequencies licensed by LightSquared. They are in an area of the spectrum normally reserved for Mobile Satellite Service.
In fact until last year, when the company (known at the time as SkyTerra) changed ownership, that was exactly what they did. The original business involved selling satellite based data services.
Low power terrestrial transceivers operating on the same frequencies as their satellite service were used to supplement the signal.
Under such a system, a dual mode device is used which can switch to a terrestrial connection when satellite service is not available. As required by law, this was authorized by the FCC.
However, under their new ownership, they received a conditional FCC waiver to use spectrum originally licensed for satellite service to offer wholesale terrestrial LTE (4G) mobile service.
Rather than a low power supplement for the satellite service, the terrestrial signal would become a separate product.
After testing earlier this year, LightSquared volunteered to drop plans to use one of their two 10MHz spectrum ranges because it was directly adjacent to frequencies used by GPS satellites.
The range in question now is much further from the GPS spectrum.
It is, however, adjacent to another range used for Differential GPS, a correction system used to improve the accuracy of GPS. According to a statement yesterday by Defense and Transportation Department officials, it would significantly impact the operation of high precision GPS receivers.
This is a direct result of the terrestrial nature of the new LightSquared signal, making it much more powerful than the adjacent satellite signals.
LightSquared has told government officials they believe the problem will be solved by the use of a different antenna for their towers, but their optimism has yet to be put to the test.
Karl Nebbia Associate Administrator, Office of Spectrum Management in the National Telecommunications and Information Administration told the committee there has been no testing to confirm their assertion.
It appears the earliest this could be resolved, assuming LightSquared's solution is viable, is the end of November. However, it could take much longer thanks to allegations that FCC Chairman Julius Genekowski improperly pushed through the waiver allowing the use of satellite frequencies for terrestrial signals.
A political battle over the situation is shaping up which could easily extend through the presidential election next November, perhaps even longer.
Written by: Rich Fiscus @ 16 Sep 2011 17:02
