The FCC had granted a conditional waiver to LightSquared, for them to continue developing their nationwide high-speed cellphone network. Apparently LightSquared never could prove that their system wouldn’t interfere with GPS and even went so far as to suggest that it was GPS’s problem, not theirs. From here:
Testing showed that LightSquared’s signal did not bleed into the GPS band. Instead, the problem was that GPS receivers were too sensitive to filter out LightSquared’s powerful cell towers operating on nearby frequencies.
LightSquared argued that it was the GPS industry’s responsibility to build receivers that only listened to their own designated frequencies, but GPS companies argued that LightSquared was trying to build a cellphone network relying on frequencies that should only be used by satellites, which transmit much fainter signals.
I can’t imagine what it would take to develop, test, and replace every GPS system out there. The FCC is revoking the waiver, and I’m sure a number of pilots and military personnel are breathing a sigh of relief. Any thoughts from the electrical engineers out there about the fight over frequencies?