LightSquared defended its plans to build an LTE network in spectrum near GPS bands at a congressional hearing this morning, where some expressed skepticism about whether the company should be allowed to launch its mobile broadband service in the L-band.
Top officials at the Department of Transportation, Defense Department and Coast Guard, as well as executives from the Radio Technical Commission for Aeronautics (RCTA), Garmin, the Aircraft Owners and Pilots Association (AOPA) and the Air Transport Association (ATA) testified that LightSquared's original network plan would have catastrophic effects on GPS systems, and said it remained unclear whether the company's revised plan would resolve the issue.
Margaret Jenny, president of the RTCA, said testing showed LightSquared's network would be compatible with GPS systems if it only operated in the 5 MHz of Inmarsat's spectrum sitting farthest away from the GPS band. However, LightSquared's revised plan calls for the company to use the lower 10 MHz of Inmarsat's spectrum, which could knock out some high-precision GPS systems, such as those used to land airplanes and conduct rescue missions.
"The lower 10 MHz need more study," Jenny said.
Some speaking at the hearing called for LightSquared to move its network to spectrum outside the L-band or give up their plans altogether.
"Like the FDA, I think they [the FCC] need to issue a recall," AOPA President Craig Fuller said, comparing LightSquared's waiver to operate a mobile broadband service to a harmful drug that erroneously passed the FDA's screening process. "This is simply a toxic drug. This will not work in the system we have today."
Phil Straub, vice president of aviation engineering at Garmin International, echoed Fuller's remarks, calling for the FCC to rescind LightSquared's waiver and move the company's service out of the L-band.
"Please do everyone a service and put an end to this dysfunctional exercise," Straub said.
Some of the lawmakers questioning witnesses at the hearing also expressed doubts as to whether LightSquared should be allowed to move forward.
Missouri Republican Congressman Sam Graves said he was "terribly concerned" about the effect LightSquared's network could have on GPS systems used in the aviation and agriculture industries.
"I'll be honest with you, I'm not comfortable with it whatsoever, I'm not supportive whatsoever," Graves said.
LightSquared spokesman Jeff Carlisle defended the company's plans, pointing out that the GPS industry had only recently voiced concerns about interference despite the fact that plans to roll out a mobile broadband service in the L-band had been years in the making.
Carlisle also stated that LightSquared was confident its plan to use Inmarsat's spectrum would resolve the interference issue for 99 percent of the estimated 500 million GPS receivers currently being used in the United States.
"Our operation in the lower part of the band does not cause interference for the vast majority of GPS receivers," Carlisle said, but admitted that "further work needs to be done" to determine whether GPS used in aviation would still be affected under the company's revised plan.
Carlisle and witnesses speaking on behalf of the GPS industry clashed over whether filters could be used to resolve the interference issue. Carlisle stated that the filters were in development and would cost just pennies to install on some devices, while Straub and Fuller questioned the existence of the technology and the practicality of outfitting millions of GPS receivers with filters.
Republican Congressman Tom Petri said that the House Aviation Subcommittee, which he chairs, may ask the FCC for time to "allow full, comprehensive study of the plans" and called for independent testing of LightSquared's revised network build.
Roy Kienitz, under secretary for policy at the Transportation Department, said that more testing would be needed for the agency to assess whether LightSquared's revised network would affect GPS if it only operated in the lower 10 MHz of Inmarsat's spectrum.
"The Department of Transportation would like to work towards a 'win-win' – if one exists - that allows for increased broadband access, without disrupting existing and planned GPS-based services, such as NextGen," he said. "Any alternative must be robustly tested, as was the original plan."