By Brendan Sasso - 09/08/11 09:42 PM EDT
In response to earlier test results that revealed GPS interference, LightSquared agreed to modify its proposal and only operate its land-based broadband network on the lower 10 MHz of its spectrum. According to LightSquared, that change will cost the company $100 million.
But government GPS operators are concerned that might not be enough to prevent serious interference issues.
In particular, LightSquared’s network could still cause problems for high-precision GPS devices.
Glackin said LightSquared might interfere with NOAA systems that model global climate data, monitor sea level trends and forecast short-term weather events.
David Applegate, associate director of natural hazards for the U.S. Geological Survey, warned LightSquared’s network could interfere with monitoring earthquakes and volcanoes.
“I agree with the agencies before us today that additional testing should be required before the [Federal Communications Commission] allows LightSquared to begin commercial service,” said Rep. Ralph Hall (R-Texas), chairman of the Science, Space and Technology Committee.
Rep. Eddie Bernice Johnson (D-Texas), ranking member of the committee, said she is hopeful GPS and LightSquared can coexist. But she said if LightSquared cannot resolve the interference issues, the FCC should not approve its proposal.
Rep. Jerry McNerney (D-Calif.) praised the potential benefits of expanded broadband access that would result from LightSquared’s network, but he expressed skepticism that the GPS problems have been fixed.
“I just don’t think we’re there yet,” he said.
"I don't want to face my constituents at a town meeting if their GPS ends up not being what it's supposed to be and what it has been as a result of spectrum interference," said Rep. James Sensenbrenner (R-Wis.).
Jeff Carlisle, vice president of regulatory affairs for LightSquared, said the previous rounds of testing provided sufficient information about the interference issues and that new testing is not needed.
He said the only remaining problems are with high-precision GPS devices, which represent a small share of all GPS devices. Those remaining problems can be fixed by putting filters on the high-precision GPS devices to prevent them from “looking into” LightSquared’s spectrum, he said.
Anthony Russo, director of the National Coordination Office for Space-Based Positioning, Navigation and Timing, disagreed, saying it is unclear whether the technology exists to prevent serious disruption with high-precision devices.
Russo said LightSquared’s network would be billions of times more powerful than nearby GPS receivers. Citing a Stanford professor, Russo said the difference between the power of GPS receivers and the power of LightSquared's network is like the difference between a teaspoon of water and Niagara Falls.