Federal Committee Says No Remedy for LightSquared Interference (1/17/12)
By Sandra Wendelken
A federal committee that provides guidance to the GPS program unanimously concluded that there are no solutions available to remedy the interference found in tests by the committee and LightSquared, which is proposing a new hybrid satellite/terrestrial broadband commercial service.
The test findings by federal agencies found that both LightSquared's original and modified plans for its proposed mobile network would cause harmful interference to many GPS receivers. Additionally, an analysis by the Federal Aviation Administration (FAA) concluded that the LightSquared proposals are not compatible with several GPS-dependent aircraft safety-of-flight systems.
“Based upon this testing and analysis, there appear to be no practical solutions or mitigations that would permit the LightSquared broadband service, as proposed, to operate in the next few months or years without significantly interfering with GPS,” said a letter to the National Telecommunications and Information Administration (NTIA). “As a result, no additional testing is warranted at this time.”
The letter, from the National Space-Based Positioning, Navigation and Timing (PNT) executive committee, said nine federal departments and agencies tested and analyzed LightSquared's proposals to repurpose the mobile satellite services (MSS) frequency band adjacent to GPS frequencies to permit another nationwide terrestrial broadband service.
LightSquared executives countered that the process used to test GPS devices by Air Force Space Command on behalf of the PNT executive committee was rigged by manufacturers of GPS receivers and government end users to produce bogus results. The company asked the FCC and NTIA to conduct the second round of tests on high-precision devices at an independent laboratory to ensure objectivity and transparency. Company officials recently said the interference issues can be at least partially alleviated through filtering technology.
“Over the past year we have closely worked with LightSquared to evaluate its original deployment plan, and subsequent modifications, to address interference concerns,” the PNT letter said. “This cooperative effort included extensive testing and analysis of GPS receivers. Substantial federal resources have been expended and diverted from other programs in testing and analyzing LightSquared's proposals.”
The committee proposed to draft new GPS spectrum interference standards that will help inform future proposals for non-space, commercial uses in the bands adjacent to the GPS signals and ensure that any such proposals are implemented without affecting existing and evolving uses of space-based PNT services vital to economic, public safety, scientific and national security needs. The FCC has yet to release an order on whether the LightSquared service can move forward.
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