At a hearing before the House Science, Space and Technology Committee yesterday, representatives of various federal agencies questioned LightSquared LLC’s latest plan to operate its proposed hybrid satellite-terrestrial wireless broadband network in the lower portion of its L-band spectrum assignment, as they called on the FCC to require further testing to assess the impact of LightSquared’s revised proposal on global positioning system (GPS) operations. In an attempt to lessen prospects that the LightSquared system will interfere with GPS receivers operating in adjacent spectrum bands, LightSquared filed an amended plan with the FCC in June that envisions initial network deployment in the 1526-1536 MHz band, which is farther away from GPS than the 1545-1555 MHz band where LightSquared had originally planned to commence operations. LightSquared has also offered to operate at one-tenth of its currently-authorized power level and contribute both monetary and expert resources in developing a solution for the small number of high-precision GPS receivers that the company claims could still experience harmful interference from its lower L-band operations. While stressing that federal agencies with GPS interests are “seeking a win-win solution” that would enable LightSquared to operate its network while protecting GPS operations, Anthony Russo, the director of the National Coordination Office for Space-Based Positioning, Navigation and Timing (PNT), emphasized to lawmakers that further testing is needed “to establish whether there are any mitigation strategies that can enable [LightSquared] operation in the lower 10 MHz portion of the band.” Along the same vein, witnesses from the National Aeronautics and Space Administration and from the Commerce, Transportation and Interior Departments recommended that the FCC should not approve LightSquared’s revised plan until further tests prove that the company’s long-term evolution network can operate safely in the lower L-band without interfering with GPS receivers. Concurring that further testing is necessary, committee chairman Ralph Hall (R-TX) said, “we have to find a way to open up more spectrum for broadband, but not at the expense of GPS.” Observing that each subgroup of the working group mandated by the FCC to analyze LightSquared’s GPS operations has already studied the lower L-band proposal and that 10 out of 38 GPS receivers tested by LightSquared “were resilient to our operations,” LightSquared Chairman Jeffrey Carlisle replied that issues of interference are related to technology “and can be addressed through proper design.”