Avionics News January 2012 - 32

industry

Next Step in the GPS Battle
S T O R Y B Y B L A N D I N G S L O A N

fter many months of tests and filings with the Federal Communications Commission, the agency seems no closer to resolving the situation it created by granting a waiver to a single company – LightSquared – to build a dense, high-powered network that threatens GPS. A new round of tests – requested by the National Telecommunications and Information Administration – on LightSquared lower-band, lower-power effects, is ongoing. But, total testing to date is far from comprehensive. Under the terms of the FCC waiver, LightSquared can’t begin operations until the agency is satisfied that the transmissions would cause no harmful interference to GPS. Does that mean stalemate? Au contraire. LightSquared has threatened to sue if its plans are foiled. But the GPS community also has thrown out a marker. The Coalition to Save Our GPS, an umbrella group of manufacturers, users and trade associations, including the Aircraft Electronics Association, has filed to foreclose any future use by LightSquared of its upper band. The Coalition said such a ruling is justified, given the unworkability of LightSquared transmissions in the upper band and the need to reduce uncertainty in spectrum ground rules.
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More than GPS here-and-now is at stake. GPS is the cornerstone of NextGen air traffic management modernization, said Tom Hendricks, senior vice president for safety, security and operations with the Air Transport Association, at a recent Coalition briefing. The prospect of stepping back in a few years’ time and going in a different direction could “hurt airspace modernization and the airline industry and set (them) back at least a decade or more,” he said. And, required navigation performance “could be off the table for the foreseeable future.” The biggest element of uncertainty is LightSquared’s unwillingness to renounce its claims to the upper band or to higher power. In public statements, the company has said it will need to access the upper band of its spectrum in “just a few years, …well within the implementation timeframe for something like NextGen,” said Jim Kirtland, vice president and general counsel for Trimble, at the briefing. Aviation equipment, because of its high certification bar, also has a long, 10-to-15-year investment decision horizon, he said. Despite “overwhelming evidence” of interference in the upper band, however, the FCC has yet to rule it out for LightSquared, the Coalition said. “It’s

very important for the FCC to state that the upper 10 is not viable,” Kirtland said. “Nor would it ever be in the public interest to push through these transitions twice.” LOWER BAND As Scott Burgett, Garmin software engineering manager, put it in a recent presentation to the Positioning, Navigation and Timing National Advisory Board, “It is impossible to design new products compatible with LightSquared’s proposed system without knowing its technical end-state.” As the FCC digests the Coalition’s move, the first phase of the newest round of testing is taking place. Focused on lower-end GPS devices, these tests include some Garmin portable (non-FAAcertified) aviation units. The FAA is supporting tests of noncertified, general aviation, visual flight rules receivers. Part of the FAA’s concern is use of GPS data in vertical alerting and in feeding terrain warning systems, according to Sai Kalyanaraman, a Rockwell Collins senior systems engineer. For example, you can use helicopter terrain warning systems down to 100 feet above ground level, which might put you close to a LightSquared tower. Separately, the FAA is working with

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Avionics News January 2012

Table of Contents for the Digital Edition of Avionics News January 2012
