Washington - GPS industry representatives went before Congress today to pan a proposal by LightSquared to reduce interference between LightSquared's planned 4G cellular network and GPS receives used by consumers and industry.

LightSquared offered to limit the initial operation of its 4G LTE network to the lower part of the L-band spectrum that it planned to use and to reduce planned base-station transmitter power by more than 50 percent. Although LightSquared said the solution would still, to some degree, likely affect precision GPS systems used by the aviation and agriculture industries, it said it would work to include solutions in a report to be delivered to the Federal Communications Commission (FCC) on July 1.

In testimony prepared for a hearing by a House Transportation and Infrastructure Subcommittee, representatives from GPS supplier Garmin, the Air Transport Association (ATA), and the Aircraft Owners & Pilots Association (AOPA) contended the only way to resolve interference would be to move LightSquare's operation out of the L band altogether to a band farther away from the GPS band.

LightSquared's mitigation proposals are either "infeasible or insufficient," a statement by the three organizations said.

Referring to plans to move LightSquared operations to a lower portion of the L band farther away from GPS frequencies and to reduce base-station output, ATA senior VP Tom Hendricks said the plans were "fraught with technical challenges not yet fully understood." Regarding a proposal to apply filters to high-precision GPS receivers, Hendricks noted that no such filters today exist.

Even if a technical fix did become feasible, the costs would be astronomical, Hendricks continued. "The U.S. airline industry simply cannot afford to purchase and install it in approximately 6,600 aircraft, which would cost billions of dollars," he contended.

Garmin aviation engineering VP Philip Straub said the LightSquared solution "conveniently ignores much of the existing user base, especially users of high precision GPS equipment."

"With so much of the early evidence showing that LightSquared's proposed network would potentially endanger nearly every flight operating in U.S. airspace, it seems evident that no further development of this system can be allowed," added AOPA president/CEO Craig Fuller.

For its part, the carrier has said that tests run by LightSquared and GPS suppliers found the lower block of frequencies to be "largely free of interference issues with the exception of a limited number of high-precision GPS receivers." To "provide additional protection," the carrier said it would reduce maximum authorized base-station transmitter power by more than 50 percent.

"This is a solution which ensures that tens of millions of GPS users won't be affected by LightSquared's launch," said LightSquared chairman/CEO Sanjiv Ahuja.