GPS Interference

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LightSquared Says GPS-Interference Issue Resolved; Others Skeptical

December 12, 2011

Last week was a tumultuous one for supporters of telecommunications provider LightSquared and the company’s proposed 4G wireless broadband network. Both the company and a key ally each claimed victory against interference with Global Positioning System (GPS) receivers, but a leaked government report says that significant work remains to be done before the issue is completely resolved for the millions of GPS devices now in the field.

On December 7, LightSquared CEO Sanjiv Ahuja announced that testing on three companies' existing GPS receivers by Alcatel-Lucent labs showed those devices, after being retrofitted with filters, were not disrupted by LightSquared's immensely strong signal bleeding onto bandwidth used by much weaker GPS signals. “Preliminary results show that GPS devices tested in the lab easily surpass performance standards thanks to these newly developed solutions” Ahuja said. “We are confident that this independent testing will mirror testing being done by the federal government.” Review the full LightSquared press release.

The next day, Javad GNSS President Dr. Javad Ashjaee provided details about his company's proposed solution to GPS interference problems. In a webinar hosted by GPS World magazine, Ashjaee stated that company tests involving the proposed fix of a ceramic signal filter, followed by a series of surface acoustic wave filters, successfully blocked the LightSquared LTE signal. “I should do this regardless of LightSquared, to provide a better signal,” he stated. “There is no need to stop progress.... My solution provides a short-term answer, but at least I'm trying to solve the problem.”

When asked what it would cost to make those retrofits to existing receivers, Ashjaee provided estimates ranging from a low of $300 for current Javad GNSS receivers, to a high of $15,000 in a “worst case” scenario for competing devices. Amortized over several years, Ashjaee asserted even that amount would work out to “less than a Big Mac a day.”

Not surprisingly, a key GPS advocate expressed skepticism of LightSquared's claims. “It's important to keep in mind that these are LightSquared-sponsored tests separate from the ongoing, independent testing being conducted under the auspices of the NTIA [National Telecommunications and Information Administration], and are simply one input into an overall analysis of the effect of LightSquared's planned operations on critical GPS uses,” said Jim Kirkland, vice president of Trimble and a founding member of the Coalition to Save Our GPS. Kirkland added that the results of the NTIA-supervised tests of consumer GPS devices were expected to be available by mid-December.

Reports: GPS Devices Remain Affected

It didn't take that long. On December 9, multiple news agencies reported the results of a leaked report, ahead of the government's formal presentation of the NTIA data. According to Bloomberg, those results showed LightSquared's signal interfered with 75 percent (69 out of 92) of GPS receivers tested. “LightSquared signals caused harmful interference to a majority of GPS receivers tested,” reads the draft, which went on to state that “millions of GPS units are not compatible” with LightSquared's proposed network.

LightSquared was quick to respond to those charges. Martin Harriman, executive vice president of LightSquared's Ecosystem Development and Satellite Business, called the leaked report “patently false” and based on “incomplete government data.... This breach attempts to draw an inaccurate conclusion to negatively influence the future of LightSquared and narrowly serve the business interests of the GPS industry.”

The full results of the NTIA tests will likely come in the next week, with the results from separate testing of high-precision receivers expected in January.

Coalition to Save Our GPS

NBAA is a member of the Coalition to Save Our GPS, which has more than 200 members and is committed to resolving the threat to GPS and preserving its benefits for industries, government and citizens. Earlier this year, NBAA President and CEO Ed Bolen submitted written testimony to a joint hearing of the House Subcommittee on Aviation and the House Subcommittee on Coast Guard and Maritime Transportation.

“Our [NBAA] Members are not opposed to the development and deployment of new or improved technology systems like LightSquared – as long as it is conclusively proven that it will not result in radio interference with GPS systems or pose any threat to the global aviation transportation system,” Bolen’s testimony stated.