Interference Studies Lead FCC to Block LightSquared Operations
NPEF test setup inside an anechoic chamber at the White Sands Missile Range, New Mexico.
On February 14, 2012, the National Telecommunications and Information Administration (NTIA) released three reports providing the unclassified results of the government's most recent LightSquared–GPS interference testing and analysis.
The reports, which follow up on previous studies released in 2011, assess potential interference to GPS devices from the nationwide "4G" network proposed by LightSquared Subsidiary LLC. Unlike the earlier studies, the new reports focus on LightSquared's offer to use only the lower 10 MHz portion of its authorized spectrum for the first few years.
Taken together, the earlier studies and the new reports demonstrate that both LightSquared's original and modified plans for its proposed mobile network would cause harmful interference to many GPS receivers.
NTIA: Cellular GPS Receivers NTIA, with LightSquared, developed a plan to validate earlier test measurements of GPS receivers used in cellular devices. Two independent test laboratories performed the validation measurements.
NPEF: Personal / General Navigation GPS Receivers At NTIA's direction, the National Space-Based Positioning, Navigation, and Timing Systems Engineering Forum (NPEF) tested the effects of LightSquared's lower 10 MHz signal on general purpose GPS devices.
FAA: Aviation GPS Receivers The Federal Aviation Administration (FAA) worked with LightSquared to conduct an analysis of the impact to certified aviation receivers of LightSquared's planned operation at the lower 10 MHz channel only.
Letters to NTIA and FCC
Based on the latest studies, the senior leaders on the National Executive Committee for Space-Based PNT concluded that, "there appear to be no practical solutions or mitigations that would permit the LightSquared broadband service, as proposed, to operate in the next few months or years without significantly interfering with GPS." They also stated that, "no additional testing is warranted at this time."View Letter to NTIA
These statements appear in their January 2012 letter to NTIA, which advises the President on telecommunications policy and represents federal agencies to the Federal Communications Commission (FCC).
NTIA issued its own letter to the FCC conveying the views of the federal agencies and NTIA's independent assessment. NTIA also submitted the NTIA, NPEF, and FAA reports for FCC and public review.View Letter to FCC
The NTIA letter concludes, "Based on the testing and analyses conducted to date, as well as numerous discussions with LightSquared, it is clear that LightSquared's proposed implementation plans, including operations in the lower 10 MHz would impact both general/personal navigation and certified aviation GPS receivers. We conclude at this time that there are no mitigation strategies that both solve the interference issues and provide LightSquared with an adequate commercial network deployment."
Upon receiving the NTIA letter, the FCC announced that "the Commission will not lift the prohibition on LightSquared. The International Bureau of the Commission is proposing to (1) vacate the Conditional Waiver Order, and (2) suspend indefinitely LightSquared's Ancillary Terrestrial Component authority to an extent consistent with the NTIA letter."
On February 15, 2012, the FCC issued a public notice inviting comments on its proposed actions via FCC Docket IB 11-109. The deadline for submitting comments was later extended from March 1 to March 16, 2012, with reply comments due March 30. View extension order...
In January 2011, the FCC authorized LightSquared to build out a nationwide network of radio transmitters for high-speed Internet access. However, the FCC required LightSquared to resolve GPS interference concerns to the FCC's satisfaction prior to operating the network.
The concerns stem from LightSquared's plan to broadcast powerful, terrestrial signals in frequencies close to the faint GPS signals from space. Though LightSquared would operate in its own radio bands, many GPS devices can pick up the stronger LightSquared signals and become jammed.
After a first round of tests showed widespread interference to GPS devices, LightSquared changed its operating plans. In September 2011, the FCC called for more testing based on a LightSquared signal at the lower 10 MHz only. The government conducted a second round of testing and analysis in October-November 2011 to see if the signal changes resolved the problem. The government did not test any proposed upgrades to GPS devices, as these were not available at the time.Get more information about LightSquared and GPS, including FCC orders, earlier studies, hearings, legislation, and more...