The controversy over potential interference to GPS from LightSquared’s planned nationwide network of powerful 4G broadband retransmitting stations has now drawn Congress into the dispute. Letters expressing concern about adverse effects of the LightSquared network on GPS have been sent to the FCC by House and Senate members. Both the civil and military GPS communities raised objections earlier this year when the FCC granted LightSquared a waiver to its satellite-only license to allow the addition of up to 40,000 terrestrial repeater stations to supplement its satellite signals. The original license allowed only relatively few ground stations, limited to locations where satellite reception was poor. In a reply to a letter from Sen. Chuck Grassley (R-Iowa), FCC chairman Julius Genachowski called upon “interested parties” to work with LightSquared to resolve GPS compatibility problems and interference concerns due to either LightSquared transmissions or, interestingly enough, GPS receivers. However, the GPS community has consistently stated that LightSquared is solely responsible for any adverse effects to GPS, including the receivers. As tensions grow, the battleground is now also moving into the media, with LightSquared’s chairman writing anop-ed column in The Hill and the company placing a full-page advertisement in a weekly aerospace trade magazine.