07.11.2011 02:05 PM
NTIA Releases LightSquared GPS Interference Study
Satellite1WASHINGTON: A federal report documenting GPS interference by the proposed LightSquared satellite-terrestrial broadband network has been released. The National Telecommunications and Information Administration recommended that the project remain on hold until the problem is solved.

“NTIA supports EXCOM’s recommendation that additional tests be performed and recommends that the FCC continue to withhold authorization for LightSquared to commence commercial operations until all the available test data can be analyzed and all valid concerns have been resolved,” said NTIA chief Larry Stricking in a letter to Julius Genachowski, head of the Federal Communications Commission, which green-lighted LightSquared in January. EXCOM is the National Executive Committee for Space-Based Positioning, Navigation and Timing, which directed the report.


It said multiphase tests of LightSquared’s proposed terrestrial transmitters demonstrated “significant detrimental impacts to all GPS applications” evaluated, including government and commercial uses. A simulation of the completed network of base stations “would result in degradation or loss of GPS function at standoff distances of a few kilometers extending to space operations,” it said.


The interference issue starting dogging LightSquared soon after it started testing transmitters. It filed a modified operational plan with the FCC June 30, taking issue GPS receiver quality. (
See “LightSquared Blasts GPS Receiver Quality.”) The company noted that GPS receivers do not adequately reject adjacent-band interference and should be made to do so per FCC rules.

The EXCOM test also observed that GPS receivers could be modified to reject interference, but that it would be “impractical, as they would require significant modification or complete redesign and replacement of currently fielded GPS equipment.


“The timeline to field new GPS receivers for some applications, from initial concept development through production, can take 10-15 years.”


The report urged the feds to conduct more thorough studies on LightSquared’s proposed network, including alternative signal configurations and handset transmissions. It recommended an additional evaluation period of “at least six months.”


LightSquared, in the meantime, is burning through cash awaiting for regulator approval. The company is funded through venture capital from Harbinger Ventures and private contributions from Harbinger’s principal, Philip Falcone. UBS and JP Morgan have also invested. The company last week announced having raised an additional $265 million from existing and new investors. It expects to sink $14 billion of private money into the network over an eight-year period.


The EXCOM report, “Assessment of LightSquared Terrestrial Broadband System Effects on GPS Receivers and GPS-dependent Applications,” is at the
NTIA website.

~
Deborah D. McAdams


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