From Connected Planet: In a letter to FCC Chairman Julius Genachowski, Sen. Chuck Grassley — ranking Republican on the Senate Judiciary Committee — asked who would pay for the retrofit of millions of military, government and commercial receivers if LightSquared’s network was given the green light. Here’s an excerpt from the letter dated Sept. 29:

“My concern regarding LightSquared’s application to create a terrestrial 4G network is that the Federal Communications Commission (FCC) appears not to have taken sufficient steps to safeguard the American taxpayer and appears to have let LightSquared off the hook regarding the multi-billion cost to retrofit GPS receivers to block out LightSquared’s terrestrial network.

“ … Despite the readily apparent concerns which were present throughout the waiver process, at no point has the FCC addressed who will pay to retrofit every single federal, state, and local government GPS receiver, which will require a filter as a result of interference caused by LightSquared’s terrestrial network.”

Grassley cited the Defense Department as the primary source of his concerns. In the letter, Grassley drew from Air Force Space Command General William Shelton’s testimony before a House Armed Services subcommittee earlier this month: “We have not estimated cost however, I think it would be very safe to say that the cost would in the Bs – billions of dollars,” Shelton said. “We believe that the time would probably be a decade or more to accomplish all this. There are probably a million receivers out there in the military, maybe even more than that.” Read the entire article here.