Start-up wireless carrier LightSquared threatened litigation if the Federal Communications Commission does not clear it to operate a network of up to 40,000 cell towers the GPS industry claims will interfere with GPS receivers.
Jeff Carlisle, LightSquared's vice president of regulatory affairs and public policy, told reporters at a briefing Monday that any interference with high-precision GPS receivers from the company's planned network results from the fact that those receivers "look" into the adjacent frequency band.
In a letter to FCC Chairman Julius Genachowski Monday, Carlisle said that GPS manufacturers have ignored standards developed by the Defense Department to block reception of transmissions from adjacent bands.
Martin Harriman, vice president of ecosystem development and satellite business for LightSquared, said that manufacturer Javad GNSS has developed a signal filter that will mitigate interference problems with high-precision GPS receivers.
Last month, the company said it planned to market filters for high-precision receivers for positioning applications by November 2011 and filters for precision timing devices by March 2012. Harriman said the filter technology developed by Javad "could possibly be used by other manufacturers."
After tests this spring showed the LightSquared system did cause interference with GPS receivers at the portion of its frequency band closest to the GPS spectrum, Carlisle said the company voluntarily agreed to limit its initial deployment to the lower 10 MHz of its spectrum, which is further from the GPS band.
In a Sept. 13 public notice, the FCC said that "results thus far from the testing using the lower 10 MHz showed significant improvement compared to tests of the upper 10 MHz, although there continue to be interference concerns . . . with certain types of high precision GPS receivers, including devices used in national security and aviation applications."
The FCC added that additional tests are necessary, and the National Telecommunications and Information Administration put the new round of tests on a fast track with plans to finish them by Nov. 30.
Carlisle said LightSquared has tried to conduct itself as a "good neighbor" to GPS receiver manufacturers and users, but threatened legal action if the FCC does not green light the company's network after the latest round of tests are completed. FCC regulations make it clear, Carlisle said, that GPS receivers are not entitled to protection from interference "if they are listening outside their band."
"If it is impossible to get a decision on this that allows us to go forward . . . that's what we'll do," Carlisle said.