Data Shows Disastrous GPS Jamming from FCC-Approved Broadcaster
February 1, 2011Representatives of the GPS industry presented to members of the Federal Communications Commission clear, strong laboratory evidence of interference with the GPS signal by a proposed new broadcaster on January 19 of this year. The teleconference and subsequent written results of the testing apparently did not dissuade FCC International Bureau Chief Mindel De La Torre from authorizing Lightsquared to proceed with ancillary terrestrial component operations, installing up to 40,000 high-power transmitters close to the GPS frequency, across the United States.
The document describing the testing states that the Lightsquared initiative “will have a severe impact on the GPS band” and “will create a disastrous interference problem for GPS receiver operation to the point where GPS receivers will cease to operate (complete loss of fix) when in the vicinity of these transmitters.”
On January 26, the FCC waived its own rules and granted permission for the potential interferer to broadcast in the L Band 1 (1525 MHz—1559 MHz) from powerful land-based transmitters. This band lies adjacent to the GPS band (1559—1610 MHz) where GPS and other satellite-based radio navigation systems operate.
The company, Lightsquared, has stated that it will work with the GPS industry to see which GPS equipment needs "filtering so that they don't look into our band." The FCC wants to start the testing process on February 25 and have it completed by June 15, 2011.
"It's a fast process," noted Lightsquared executive vice president for regulatory affairs and public policy Jeff Carlisle.
Prior to the decision, representatives of the U.S. GPS Industry Council and two prominent GPS manufacturers, Garmin and Trimble, presented a report, “Experimental Evidence of Wide Area GPS Jamming That Will Result from LightSquared’s Proposal to Convert Portions of L Band 1 to High Power Terrestrial Broadband,” to five members of the FCC’s Office of Engineering and Technology, including its chief, two members of the FCC International Bureau, one from the Public Safety and Homeland Security Bureau, and two from the Wireless Telecommunications Bureau.
Click on the following link for a full PDF of the Experimental Evidence of Wide Area GPS Jamming.
The document conveys results of testing on a common portable consumer automotive navigation device and on a common general aviation receiver. The consumer GPS device began to be jammed at a power level representing a distance of 3.6 miles (5.8 kilometers) from the simulated LightSquared transmitter. The consumer device lost a fix at 0.66 miles (1.1 kilometers) from the transmitter.
The Federal Aviation Administration (FAA)-certified aviation receiver began to be jammed at a distance of 13.8 miles (22.1 kilometers) and experienced total loss of fix at 5.6 miles (9.0 kilometers) from the transmitter.
During the laboratory testing, GPS signals were simulated by a Spirent GSS 6560 GPS simulator, representing a constellation of 31 GPS satellites, the current configuration. LightSquared’s signal was simulated using a Rhode and Schwartz SMIQ-03S signal generator with digital modulation, amplified to achieve the relevant signal strengths. Full technical specifications and parameters are described in the Experimental Evidence document linked above.
The industry report concludes: “As shown by the Garmin testing described in this document, the proposed LightSquared plan to add 40,000 high-powered transmitters in the band adjacent to GPS will result in widespread, severe GPS jamming. This will deny GPS service over vast areas of the United States.”
In its subsequent decision document on January 26, the FCC not only authorized LightSquared to proceed, it turned up its nose at assertions that the entire process had been conducted in near-stealth mode as well as on an accelerated track. Lightsquared filed its petition to the FCC just prior to the U.S. Thanksgiving holiday, and much of the process transpired during the run-up to winter holidays. “We conclude that the pleading cycle for LightSquared’s request — in which the Comment Public Notice was issued on November 19, 2010, with comments due on December 2, 2010, and reply comments due on December 9, 2010 — is sufficient for the decisions we make herein.”
In a passage far down the FCC decision document that specifically addresses GPS, the Commission states:
“GPS AND OTHER INTERFERENCE CONCERNS
A. GPS-Related Interference Concerns
39. Several commenters raise concerns about potential interference to GPS receivers and other devices that may result from operation of LightSquared’s base stations, while LightSquared asserts that it continues to meet its obligations with regard to addressing interference concerns. NTIA also expresses concern that LightSquared’s services could adversely impact GPS and other GNSS receivers, and asks that the Commission address these inference issues before interference occurs. We emphasize that any potential interference to GPS is a significant concern, and note that the Spectrum Task Force at the Commission recently established an internal technical working group dedicated to examining this issue. 40. The U.S. GPS Industry Council proposes that NTIA, working with industry and government technical experts, examine the potential for interference within a reasonable time frame, not to exceed 90 days.In its letter, NTIA states that, if the Commission grants LightSquared’s request, the Commission should establish a process that will ensure the interference issues are resolved prior to LightSquared’s offering service that could cause interference, and that will motivate all parties to move expeditiously and in good faith to resolve the issues. NTIA further states that it stands ready to work with the Commission, LightSquared, and affected parties and concerned Federal agencies to address these interference concerns. More recently, LightSquared states that it takes the concerns raised by the GPS community about possible overload of GPS devices by LightSquared’s base stations very seriously, and that it is appropriate for interested parties to devote resources to a solution as soon as possible.
LightSquared professes confidence that the issues can be resolved without delaying deployment of its network. At the same time, in order to address the concerns raised, LightSquared states that it would accept, as a condition of the grant of its request, the creation of a process to address interference concerns regarding GPS and, further, that this process must be completed to the Commission’s satisfaction before LightSquared commences offering commercial service, pursuant to the approval of its request, on its LBand MSS frequencies. Further, LightSquared commits to working diligently and cooperatively with the Commission, NTIA and the Federal agencies, and the GPS community to help resolve the interference issues through a rigorous process that can address these issues in a comprehensive manner.
41. We agree on the need to address the potential interference concerns regarding GPS as LightSquared moves forward with plans to deploy and commence commercial operations on its network.Further, we believe that establishing a working group that brings LightSquared and the GPS community together to address these interference issues expeditiously would serve the public interest. We envision a working group in which cooperative and candid discussions can ensue, and where information, including proprietary information, can be shared among the participants with appropriate measures in place to protect the confidentiality of that information. Commission staff will work with NTIA, LightSquared, and the GPS community, including appropriate Federal agencies, to establish a working group to fully study the potential for overload interference to GPS devices and to identify any measures necessary to prevent harmful interference to GPS. As a condition of granting this waiver, the process described below addressing the interference concerns regarding GPS must be completed to the Commission’s satisfaction before LightSquared commences offering commercial service pursuant to this waiver on its L-band MSS frequencies.
42. As an additional condition of granting this waiver, we require LightSquared to help organize and fully participate in the working group described above. The working group shall focus on analyzing a variety of types of GPS devices for their susceptibility to overload interference from LightSquared’s terrestrial network of base stations, identifying near-term technical and operational measures that can be implemented to reduce the risk of overload interference to GPS devices, and providing recommendations on steps that can be taken going forward to permit broadband wireless services to be provided in the LBand MSS frequencies and coexist with GPS devices. Because the GPS interference concerns stem from LightSquared’s transmissions in its authorized spectrum rather than transmissions in the GPS band, the Commission expects full participation by the GPS industry in the working group and expects the GPS industry to work expeditiously and in good faith with LightSquared to ameliorate the interference concerns.
43. Further, we require that LightSquared submit an initial report to the FCC and NTIA by February 25, 2011, that includes a work plan outlining key milestones for the overall analyses. In addition, LightSquared must submit progress reports on the 15th day of each succeeding month or first business day thereafter. The first of these reports must at a minimum include base station transmitter characteristics, categories of GPS devices and their representative performance characteristics, and test plans and procedures. LightSquared is further required to submit a final report no later than June 15, 2011, that includes the working group’s analyses of the potential for overload interference to GPS devices from LightSquared’s terrestrial network of base stations, technical and operational steps to avoid such interference, and specific recommendations going forward to mitigate potential interference to GPS devices. The Bureau reserves the right to adjust the reporting dates and requirements in consultation with NTIA. The process will be complete once the Commission, after consultation with NTIA, concludes that the harmful interference concerns have been resolved and sends a letter to LightSquared stating that the process is complete.”
The full PDF of the FCC decision is available here.
For further background on this story, see GPS Community Urged to Contact Congress Regarding FCC Proposal.
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