As LightSquared wraps up another round of testing on its new approach to deploy a broadband-wireless network, lawmakers are pushing measures to prevent the plan from moving forward until they are satisfied that the network would not interfere with GPS use.

U.S. Sen. Pat Roberts (R-Kan.) attached an amendment to the financial services and government affairs appropriations bill prohibiting the Federal Communications Commission (FCC) from using any funds to permit LightSquared to build the network until concerns regarding GPS interference are addressed.

LightSquared is undergoing another round of testing to determine whether GPS receivers are susceptible to interference from LightSquared’s revised plan to use lower-power, lower-frequency terrestrial transmitters. The testing is slated to be completed Nov. 30.

“The FCC must be involved in this process, and the commissioners must require an objective demonstration of non-interference before LightSquared’s system gets the go-ahead,” Roberts says. “GPS is too important for any interference to be tolerated.”

The Roberts measure is similar to an amendment included in the House version of the financial services appropriations bill. That amendment was sponsored by Reps. Kevin Yoder (R-Kan.) and Steve Austria (R-Ohio). The Roberts measure also follows a letter from Rep. Sam Graves (R-Mo.) to the FCC in which he urges the agency to hold off on approval of LightSquared’s revised plan.

The financial services appropriations bill originally was included in a second multi-agency “minibus” appropriations package, but that package appeared to unravel shortly before Congress recessed for the Thanksgiving holiday.