Various reports about recent testing performed to decide whether the proposed LightSquared Network will broadcast harmful interference to GPS say that, in fact, there will be a significant disruption to the GPS system.
This potential threat to GPS, that much of the professional land surveying industry and other industries rely upon, is due to a waiver granted late last year by the FCC to allow a company called LightSquared to build a terrestrial based broadband internet network in the 1,525MHz to 1,559MHz L-band, which is immediately next to the 1559–1610 MHz band used by GPS. This waiver by the FCC, however, was made contingent upon LightSquared and the GPS industry resolving any potential interference problems. The recent testing was performed to determine just that.
You can visit this website to learn more about LightSquared and GPS.
GPS Interference From Proposed LightSquared Network Testing Roundup
Here is a roundup of some of the recent news about the GPS interference from the proposed LightSquared network:
- GPS World
"Deere & Company, a major provider of precision agriculture equipment and services, notified the Federal Communications Commission (FCC) on May 26 of substantial interference with its GPS receivers by the LightSquared signal. Deere receivers registered impact of and interference by the LightSquared signal as far away as 22 miles from a transmitter. Further, the company has found no practicable technical solution to the problem. Deere met with an FCC legal advisor to report on its analysis of recent New Mexico tests of the Lightsquared signal and effects on GPS equipment.
The U.S. military conducted anechoic chamber tests at a White Sands facility and open-air tests at Holloman Air Force Base in April. The tests, which simulated various cellular base station transmission schemes proposed by LightSquared in L-band frequencies between 1525-1559 MHz, without exception demonstrated severe interference to Deere’s high-precision GPS receivers.
The tests included configurations where the simulated emission was reduced in bandwidth and/or assigned to frequencies in the lower part of the L-band. The Deere presentation contains an interesting graphic showing how high-precision receivers are more affected by the proposed LightSquared signals than are consumer grade receivers...."
Professional Land Surveyor Source: GPS World -John Deere: Massive LightSquared Interference with No Solution in Sight
- TWICE Mobile
"Washington - Testing required by the Federal Communications Commission (FCC) to determine whether LightSquared's planned 4G LTE network will interfere with GPS equipment has found there will be "substantial interference," a lobbying group contended today.
"The test data discussed today makes clear that there is substantial interference to GPS if LightSquared turns on high-powered terrestrial facilities in the spectrum next door to GPS," said James Kirkland, a VP of Trimble Navigation and founding member of the Coalition to Save Our GPS.
The group consists of companies in the aviation, agriculture, transportation, construction, engineering, and surveying industries as well as suppliers of GPS-based equipment and services...."
Professional Land Surveyor Source: TWICE Mobile - Tests Confirm LightSquared's GPS Interference, Group Contends
- The Wall Street Journal
"WASHINGTON—LightSquared's plan to launch a new national wireless broadband network faces a setback as preliminary tests suggest the start-up's network could knock out some GPS systems.
LightSquared's interference problems could slow down FCC approval of its new network and create problems for other companies – including its primary financial backer, Harbinger Capital Partners, the hedge fund led by Philip Falcone. Harbinger and its affiliates have put $2.9 billion of assets into LightSquared, according to a LightSquared statement.
Harbinger has run into a series of other problems recently, as investors have withdrawn money and regulators have probed certain of the firm's...."
Professional Land Surveyor Source: The Wall Street Journal - LightSquared's Wireless Network Interferes With GPS
- Coalition to Save Our GPS
"WASHINGTON, June 9, 2011 /PRNewswire-USNewswire/ -- Speaking today at an event sponsored by the National Space-Based PNT Advisory Board, Jim Kirkland, Vice President and General Counsel of Trimble, a founding member of the "Coalition to Save Our GPS" sent a strong message to the Federal Communications Commission (FCC):
"The test data discussed today makes clear that there is substantial interference to GPS if LightSquared turns on high-powered terrestrial facilities in the spectrum next door to GPS," Kirkland said. "The data confirm what the industry told the FCC before it granted the waiver, and also confirms that there is no viable technical fix. It's time for the FCC to stop squandering resources trying to find a solution to an unfixable problem. Instead, it should focus its efforts on finding spectrum that LightSquared can operate in -- where LightSquared won't interfere with GPS.
"When it comes to broadband and GPS, it's not an either/or situation -- the United States can, and should have both. LightSquared says it has other spectrum and it should use it," Kirkland said.
At issue is an unusual waiver granted to LightSquared in January by the FCC's International Bureau allowing the dramatic expansion of terrestrial use of the mobile satellite spectrum (MSS) immediately neighboring that of the GPS -- utilizing extremely high-powered ground-based transmissions that tests have shown will cause interference to hundreds of millions of GPS receivers across the United States.
At the event, Kirkland and government representatives discussed testing conducted to measure interference to GPS receivers used in aviation and other critical government applications. In at least one test, LightSquared failed to deliver test equipment that matches its proposed operations, thus causing optimistic results -- and even those optimistic results showed interference.
"It's clearly a good thing that LightSquared is trying to do," Kirkland said. "No one in the GPS industry opposes its goals of increasing wireless data capacity and competition, but the available data has shown overwhelming interference, and LightSquared should not be allowed to launch in the spectrum adjacent to GPS."
A joint industry report is due to the FCC on June 15th, when the FCC will begin a public comment period before making its final decision."
Professional Land Surveyor Source: Coalition to Save Our GPS - FCC Should Focus Its Efforts on Finding a Practical Way for LightSquared to Proceed - Tests Confirm Planned Network Will Cause Substantial Interference
"This report documents a study conducted by RTCA Special Committee 159 in response to a request from the Federal Aviation Administration to address the issue of compatibility between the operation of a terrestrial wireless broadband network in the bands 1525-1559/1626.5 – 1660.5 MHz by LightSquared, pursuant to its FCC license, and GPS receivers onboard aircraft.
The report addresses the issues analytically based on existing domestic and international standards and includes results of tests of four certifiedaircraft GPS receivers.The study concludes that the current LightSquared terrestrial authorization would be incompatible with the current aviation use of GPS, however modifications could be made to allow the LightSquared system to co-exist with aviation use of GPS. The study’s conclusions and recommendations are strictly based on an assumed set of operational parameters for the LightSquared system and identified source mitigations. These operational parameters would produce less Radio Frequency Interference (RFI) than if LightSquared were to operate at its fully-authorized limits.
In addition, the analysis is based upon the assumption that all equipment is minimally compliant with the interference rejection requirements in harmonized domestic and international standards. Additionally since GPS is an aviation safety service, the analysis includes 6 dB safety margin as is standard practice. Results from the four receivers tested show that these receiver models are significantly more resilient to interference from the LightSquared terrestrial base stations than limits derived from the standards...."
If you are interested in protecting GPS please join the Coalition to Save Our GPS.