However, "if they want to claim that they're entitled to some performance from the GPS constellation, then [the DoD standard is] the standard they need to meet. ... If they go outside those standards, they're taking a risk," Carlisle said.

LightSquared has said for several months that the GPS industry is to blame for the interference, but it did not make any claims about the DoD recommendation earlier, partly because it needed to verify that the highly technical document was still current and was considered authoritative, Carlisle said. "You don't want to say something like this prematurely," he said.

In addition to the DoD recommendation, the International Telecommunication Union, a United Nations agency, has also warned since 2000 that stronger filtering might be necessary to protect GPS from nearby transmissions, LightSquared said.

The Coalition to Save Our GPS, which has led the fight against LightSquared's proposed network, defended the filters used in GPS devices and called the latest filing a sign of "desperation" by LightSquared.

"GPS receivers incorporate filters that reject transmissions in adjacent bands that are hundreds of millions of times more powerful than those of GPS. What LightSquared is proposing, however, is to transmit signals that are at least one billion times more powerful," the group said in a statement. "There has never been, nor will there ever be, a filter that can block out signals in an immediately adjacent frequency band that are so much more powerful, nor has LightSquared put forward any credible, independent expert opinion or other evidence that this is possible."