New tests: LightSquared interferes with GPS

Fri, 06/10/2011 - 8:05am
Maisie Ramsay, Wireless Week

New government tests show LightSquared's planned LTE network interferes with GPS service.

LightSquared's planned hybrid satellite-terrestrial LTE network sits in spectrum directly adjacent to bandwidth used by GPS, sparking concern that the high-powered signals coming from LightSquared's network will overload sensitive GPS receivers.

The National Space-Based PNT Advisory Board reported yesterday that a series of 32 tests showed significant interference on GPS receivers used by the Federal Aviation Administration (FAA), John Deer, U.S. Coast Guard, NASA and Garmin.

FAA said LightSquared's transmitters caused "significant measured degradation" in GPS equipment used in aircraft. NASA reported similar results, saying the service caused "significant interference effects to space receiver."

Simulations from the advisory board found that if LightSquared were allowed to turn on the 40,000 base stations needed for its LTE network, GPS service would be knocked out within miles of each base station and affect GPS service used by NASA in space.

The group was unable to identify any way to mitigate the interference problem and suggested LightSquared deploy its network in different spectrum or substantially reduce the power of its transmitters, which would increase the number of base stations needed to provide coverage.

The report is bad news for LightSquared. The FCC gave the company a waiver to build land-only LTE service in its satellite spectrum in January on the condition that the network would not interfere with GPS service. The agency has said LightSquared will not be able to launch its network until the GPS interference issue is resolved.

LightSquared has issued a series of reports on the issue tracking the progress of interference testing and will release its final report on June 15.

LightSquared spokesman Jeff Carlisle was not immediately available for comment but said in a press call earlier this month that LightSquared still plans to launch the network on time early next year.


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