LightSquared is trying to get off the ground as a viable wireless carrier. It's struggling because it uses both ground towers and satellites. But, critics have said it messes with GPS signals. The FCC has said LightSquared has to resolve this issue to move forward. A report from both sides has found that yes, LightSquared messes with GPS. But, LightSquared sent a letter to the FCC saying it's all the GPS makers' fault, and should have been taken care of a decade ago. Now, the GPS industry is firing back. Hillicon Valley has an excerpt from letter the GPS industry sent the FCC. Be warned - there's some geek chow at the tail end of the graph:

"LightSquared is wrong, and its arguments reflect its fundamental lack of technical understanding of GPS and the profound technical difference between how communication and satellite navigation signals operate and are received," the GPSIC wrote.

LightSquared had accused GPS makers of not following Defense Department standards in designing their receivers, but the GPSIC noted that the Defense Department standards apply to military, not commercial, receivers.

"[LightSquared's] August 11 Letter changes nothing, and must be rejected as just another flawed effort on LightSquared's part to deflect attention from the technical and regulatory inappropriateness of introducing 4G LTE service into the 1525-1559 MHz and 1626.5-1660.5 MHz bands," the GPSIC wrote, referring to the sections of spectrum that LightSquared plans to use for its nationwide broadband network.

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