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Feds: LightSquared interferes with 'majority' of GPS

Thu, 12/15/2011 - 1:47pm
Maisie Ramsay, Wireless Week

A key government committee said Wednesday that LightSquared’s network affects a “majority” of general purpose GPS receivers and technology used to land planes, but it doesn’t appear to have a significant impact on cell phones.

"LightSquared signals caused harmful interference to the majority of other tested general purpose GPS receivers," said Anthony Russo, director of the National Coordination Office for Space-Based Positioning, Navigation and Timing. "Separate analysis by the Federal Aviation Administration also found interference with a flight safety system designed to warn pilots of approaching terrain."

The federal advisory committee examined tests of LightSquared's revised deployment plan, which moved its transmissions into airwaves located farther away from GPS bands. LightSquared had said the new plan would solve the majority of issues with GPS interference, but the preliminary test results suggest otherwise.

The PNT committee is still working on its final analysis of the tests "over the next several weeks." When complete, the results will be sent from the NTIA to the FCC.

The FCC has said it will not allow LightSquared to launch its wholesale LTE network until it resolves issues with GPS interference, but it could not be immediately reached for comment on the latest report.

LightSquared CEO Sanjiv Ahuja said that he "profoundly" disagreed with the government's analysis and again claimed GPS manufacturers' faulty designs were to blame.

"We profoundly disagree with the conclusions drawn with respect to general navigation devices," he said. "Interference issues are not caused by LightSquared's spectrum, but by GPS devices looking into spectrum that is licensed to LightSquared. We have taken extraordinary measures – and at extraordinary expense – to solve a problem that is not of our making."

The preliminary results announced by the PNT committee yesterday are similar to a report leaked to Bloomberg last week, which showed that LightSquared's proposed service interfered with 75 percent of GPS receivers tested by the government.

LightSquared said the report was purposely released to damage its reputation and wants the government to investigate the leak.

The results from the first round of tests don’t bode well for a second phase of tests on timing devices and high-precision GPS receivers, which are more sensitive to interference than other electronics. The government is still conducting those tests, and its final report isn’t expected until February.

LightSquared has come out with a bevy of filters and receivers it says can make its network compatible with GPS, and this week it offered to keep its on-ground transmissions at lower levels as it strives to come up with ways to address the interference issue.

Many in the GPS industry describe the issue as an insolvable problem of physics.

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