More Tests Show LightSquared Interference With GPS

A new set of tests by the National PNT Engineering Forum, a federal advisory group of engineers, showed that LightSquared's proposed mobile broadband network disrupted the signal strength to all GPS devices in the test area, the Wall Street Journal reports.

A separate Federal Aviation Administration-commissioned study found that "GPS operations below 2000 feet would be unavailable over a large radius of metro (areas)" for aircraft.

LightSquared argues it can prevent such interference, using better filters and possibly by creating bigger guard bands, though that will reduce the amount of useful spectrum LightSquared can use. The basic problem is that the adjacent GPS signals are quite weak, compared to the much-stronger Lightsquared signals.

But interference with other licensed users is the kiss of death for any new user of spectrum. It appears the interference issues are more substantial than LightSquared had expected, and it seems doubtful LightSquared's plans can proceed without substantial modification. There undoubtedly will be some demand that the plan be scuttled.

More Tests Show LightSquared Interference With GPS (subscription required)