GPS Interference

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NBAA Calls Upon FCC to Maintain GPS Network Integrity

Comments Note Importance of Technology to NextGen Plans

August 2, 2011

Comments submitted July 28, 2011, by the National Business Aviation Association (NBAA) call for the Federal Communications Commission (FCC) to maintain "the complete integrity of the GPS signal," over plans by telecommunications provider LightSquared to overpower those frequencies with its 4G-LTE wireless network.

"NBAA is concerned that the waiver granted earlier this year by the Commission [FCC] to LightSquared, regardless of its good intentions and the caveats it employed, was a rush to judgment," reads a letter from Steve Brown, Senior Vice President, Operations & Administration to FCC Secretary Marlene Dortch. "We wish to join those expressing concerns and dismay over the interferences the proposed LightSquared system will impart on the Global Positioning System (GPS) L Band frequencies."

Review the full NBAA letter to the FCC (48KB, PDF)

The letter comes in response to a request for public comment following LightSquared's June 30 filing with the Commission, in which the company admitted signals from its proposed network would interfere with weaker GPS signals on adjacent bandwidth. As NBAA reported, a separate study filed by the FCC technical working group (TWG) tasked with resolving the frequency-sharing issue, determined a solution likely isn't possible in the near future.

"NBAA has closely monitored the activities of the FCC-mandated technical working group co-chaired by LightSquared and the United States Global Positioning System (GPS) Industry Council (USGIC)," the Association states. "Virtually all results have indicated that interference will decimate the signals-in-space of the GPS and make virtually useless millions of GPS receivers."

In its comments, NBAA illustrates the aviation community's support for new technology, including early development of what evolved into LightSquared's proposed ground-based wireless network. "Previously, we were involved during the development of the FCC original ancillary terrestrial component concept," the letter reads. "It was never envisioned at that time to have anything near the power output or functionality found in the current LightSquared proposal. It never would have been supported by the industry if that had been the case."

Subsequent developments, the letter adds, led to the industry's realization that "the spectrum under US and ITU regulation was not wholly appropriate for the ancillary system being proposed. Now, the LightSquared application has proven the naysayers to have been prophetic."

Perhaps the greatest concern over LightSquared's plans, even compared with the immediate impact such a network would have on existing GPS users, is the importance of global positioning technologies to the Federal Aviation Administration's NextGen air traffic control network.

"There is now no question that without the complete integrity of the GPS signal, the FAA's multi-billion dollar planned deployment of the Automatic Dependent Surveillance-Broadcast (ADS-B) system (which serves as the foundation for the satellite-based Next Generation Air Transportation System [NextGen]) will not be possible," NBAA points out. "These concerns are obviously of vital importance to the safety, security and economic viability of our national air transportation system, and the FCC must participate in totally mitigating all attendant issues before any LightSquared or similarly proposed system can be allowed to go live in any spectral proximity to the GPS portion of the L Band.

"Our members are not opposed to the development and deployment of new or improved technology systems like LightSquared has proposed," the letter concludes, "as long as it is conclusively and unequivocally proven that it WILL NOT result in RFI (Radio Frequency Interference) with GPS systems or components or pose any threat to the global aviation transportation system."

Earlier this year, NBAA was among more than 200 entities that joined forces to form the Coalition to Save Our GPS, which is committed to resolving the threat to GPS and preserving its benefits for industries, government and citizens. The FCC is not expected to determine whether the company may proceed with its plans until September.