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LightSquared broadband service could interfere with GPS signals

LightSquared's teaming of ground- and satellite-based antennas for a wireless broadband network could foul up GPS and other signals, early tests suggest.

June 15, 2011|By Scott Canon

Reporting from Kansas City, Mo. — Early tests for a revolutionary teaming of ground- and satellite-based antennas for a wireless broadband network suggest that it could foul up GPS and other signals.

Preliminary test results released this week could set back plans for LightSquared Inc. of Reston, Va.

Garmin and others in the satellite-guided navigation industry have been warning that LightSquared's plan poses a threat to global positioning system devices.

A LightSquared executive conceded that the tests indicated that at some frequencies and power levels the company's technology could interfere with other signals. But he said adjustments could be made to safely bring the service to market.

"There are still ways we can coexist," said Jeff Carlisle, a LightSquared vice president.

The GPS industry saw the testing as more damning.

"There is no viable technical fix," said James Kirkland of GPS maker Trimble Navigation.

An official working with the organization overseeing the testing — the National Coordination Office for Space-Based Positioning, Navigation and Timing — said the science was not yet clear on how vexing the radio interference problems might ultimately prove.

"I don't think anybody knows yet," said the official, Air Force Col. Robert Hessin.

LightSquared has a tentative go-ahead from the Federal Communications Commission to build a network that toggles between earthbound cell towers and satellite receivers. The combined ground-space network could theoretically deliver high-speed signals to mobile devices and give coverage to almost every nook and cranny of the U.S. LightSquared plans to wholesale the service to carriers such as Sprint Nextel Corp. and to electronics makers.

But FCC approval depends on further scientific study to make sure that the LightSquared network won't jam other signals. It has been assigned a little-used frequency that cellphones haven't touched before. That frequency borders on, and runs the risk of bleeding into, wavelengths set aside for GPS signals.

Testing done so far shows significant interference when the LightSquared technology operates at the highest range of the frequencies allotted to it by the FCC. Hessin said moving to lower frequencies in its assigned spectrum might help, and representatives of the aviation industry have signaled that might work. Still, he said, that will require new tests.

LightSquared's Carlisle said he thought the company could make changes without destroying the economics of its network. The company still expects to meet an FCC mandate to deploy a service that reaches 100 million Americans by the end of 2012, he said.

Canon writes for the Kansas City Star/McClatchy.

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