New LightSquared Plan Fails To Ease GPS Interference Worries
SAN FRANCISCO — A recent proposal byto modify its plans to deploy a U.S. broadband network in a way that would decrease its interference with GPS receivers has done little to allay concerns raised by representatives of federal agencies that rely on precise GPS signals for transportation, communications, weather forecasting, disaster response and scientific research.
Government executives testifying Sept. 8 before the U.S. House Science, Space and Technology Committee called for additional testing of the proposed LightSquared network in light of the company’s plan submitted June 30 to the U.S. Federal Communications Commission (FCC) to mitigate its interference on GPS receivers by concentrating its initial service to a 10-megahertz block of the L-band spectrum that is farther from the GPS spectrum band than the portion of the spectrum the Reston, Va.-based startup previously planned to use. That proposal was submitted to the FCC shortly after a government working group completed extensive testing of the LightSquared network and concluded that it would cause serious interference with GPS receivers.
“Federal agencies are recommending further testing of the proposed LightSquared configuration,” said Anthony Russo, director of the National Coordination Office for Space-Based Position, Navigation and Timing. Russo added, however, that after previous testing of the LightSquared network, the federal working group tried unsuccessfully to think of ways the LightSquared network could coexist with GPS. “After considering the full range of options, [the working group] could not identify any feasible option that would both mitigate harmful interference for, not all but most, GPS users and still allow LightSquared to meet their system requirements,” Russo told lawmakers.
Jeffrey Carlisle, LightSquared’s executive vice president for regulatory affairs and public policy, disputed that claim and suggested that LightSquared could provide a valuable service to U.S. customers without interfering with the vast majority of GPS receivers. While a fraction of the government’s receivers would still experience interference as a result of the latest LightSquared proposal, that interference could be mitigated through the use of sophisticated GPS antennas, he said.
“Americans do not have to choose between a robust GPS and a competitive broadband wireless network,” Carlisle said. “They can have both because this is an issue of responsible receiver design and coordination of the network. It is a technical issue that can be solved just as it is solved every time anybody deploys a wireless network in the United States.”
Carlisle acknowledged that between 500,000 to 750,000 of the 400 million GPS receivers currently used in the United States could still experience some interference from the LightSquared signal in the lower 10-megahertz channel. However, LightSquared is willing to “fund research into resilient precision devices and coordinate the deployment of our network to avoid interference with” those receivers, Carlisle said.
Government officials testifying at the hearing were not satisfied with that plan, saying the high-precision GPS receivers affected by the LightSquared network play such important roles in science and research applications that their accuracy could not be jeopardized. For example, some U.S. National Oceanic and Atmospheric Administration (NOAA) programs that monitor weather on Earth and detect solar storms would be harmed by the LightSquared service even if that service were limited to lower power levels and the lower portion of the spectrum band as the company proposed, Mary Glackin, NOAA deputy undersecretary, told members of the House panel.
Similarly, NASA officials are concerned that the deployment of the LightSquared network will harm ongoing Earth and space science programs. “At this time it is clear to NASA that the FCC-imposed condition requiring resolution of the GPS interference issue prior to commencing commercial operations has not been satisfied including by LightSquared’s modified plan of June 30,” said Victor Sparrow, director of spectrum policy, space communications and navigation in NASA’s Space Operations Mission Directorate. “The impact to NASA’s GPS systems from interference created by the network would be substantial.”
Lawmakers repeatedly mentioned their desire to maintain GPS service without interference and to support the LightSquared venture with its potential to create jobs and inject money into the economy. “Can we use the L-band or some portion of it for an Earth-based broadband network without damaging GPS?” asked U.S. Rep. Eddie Bernice Johnson of Texas, the ranking Democrat on the House panel. “I hope the answer is yes. LightSquared plans to invest $14 billion and employ 15,000 people. … We are desperately in need of jobs, profit and growth.”
Rep. Donna Edwards (D-Md.) added that the LightSquared plan pits the government’s reliance on GPS against President Barack Obama’s goal of expanding broadband service to underserved communities. “Given the level of investment the federal government has made and the competing policy directives, why it is that our agencies don’t have some responsibility to figure out a solution that allows LightSquared to move forward and at the same time protect our vital GPS services?”
Government officials said they have tried to find a solution that would allow LightSquared to deploy its broadband network.
Carlisle expressed frustration with government officials and the GPS community. When LightSquared began working with the FCC on its proposed network in 2001, government officials balked at the possibility that the LightSquared signal would exceed its allotted spectrum and bleed over into the GPS band, Carlisle said. To prevent that from happening, LightSquared developed filters to limit emissions outside of its spectrum band.
It was not until long after those concerns were satisfied that government and industry officials raised another issue, warning that even the modified LightSquared plan would interfere with certain GPS receivers that require precise timing information for scientific and technical applications. That issue “was first raised by the GPS industry council in September of last year after we had already committed $4 billion to this project on the basis of rules that had been written [by the FCC] six years previously,” Carlisle said.
After trying to satisfy government concerns and reduce the network’s impact on GPS, “we are moving forward with the proposal to establish a competitive broadband network,” Carlisle said.
Nevertheless, Scott Pace, director of the Space Policy Institute at George Washington University, suggested that the conflict between government agencies and LightSquared will be difficult to resolve. “There is no viable or verifiable technological solution that has been identified to date that would allow a ground-based broadband communications network to operate in close proximity to GPS signals,” Pace said.