New government test results show that a proposed high-speed wireless broadband network being launched by a company called LightSquared could jam GPS systems used for aviation, public safety, military operations and other uses.
The results released this week by a federal working group come amid mounting concern that LightSquared's planned network could cripple GPS systems embedded throughout the nation's infrastructure.
The FCC sees the LightSquared network as one part of a broad government push to bring high-speed Internet connections to all Americans. It would cover at least 92 percent of the U.S. by 2015.
But the company's plans have set off alarm bells among GPS equipment makers and the many government agencies and companies that rely on GPS systems, because LightSquared's network would use airwaves right next to those already set aside for GPS. They warn that sensitive satellite receivers — designed to pick up relatively weak signals coming from space — could be overwhelmed when LightSquared starts sending high-powered signals from as many as 40,000 transmitters on the ground.
"LightSquared's network could cause devastating interference to all different kinds of GPS receivers," said Jim Kirkland, vice president and general counsel of Trimble Navigation Ltd., which makes GPS systems.
Faced with these concerns, the FCC has made clear that LightSquared cannot launch its network until the interference problems are resolved. It is requiring the company to participate in a technical working group with GPS manufacturers and users to study the matter.
Results compiled by a working group of the National Executive Committee for Space-Based Positioning, Navigation, and Timing — a government organization that advises and coordinates among federal agencies that rely on GPS technology — found potential for widespread GPS interference. The tests showed that wireless signals from LightSquared's planned network interfered with GPS receivers used by the Coast Guard and NASA and caused Federal Aviation Administration GPS receivers to stop functioning altogether.
Despite the test results released so far, the FCC insists the interference questions are far from settled. "Some of the tests to date may have relied on different assumptions, metrics and mitigation assumptions, and so may not accurately reflect the potential for interference as a result of how the network may be operated," the agency said.
LightSquared executive vice president Jeffrey Carlisle said he remains confident that the company's new network and GPS systems can co-exist. After all, he noted, findings of interference do not come as a surprise. What matters, he said, is what can be done about the interference.
Among the solutions outlined by the government working group: modifying LightSquared's antenna patterns and reducing the power levels of its base stations; limiting the slices of airwaves that LightSquared can use or moving the company to a different part of the spectrum; and installing better filters on GPS receivers to screen out LightSquared's signals.
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