More Tests Show GPS Interference

A news report this weekend from AP reports that additional tests have been showing potential interference with GPS signals from the planned deployment of the new LightSquared high-speed broadband wireless network. The so-called 4G network is part of the FCC’s general plan to push high-speed internet access to larger portions of the US population.




The article expands on the results from the previous tests that I reported on in an earlier blog. They note that during the tests in April at Holloman Air Force Base in New Mexico “GPS receivers built into farm equipment made by John Deere lost signals, as did most General Motors' OnStar navigation systems”.



Apparently as a result of the John Deere tests the House Appropriations Committee has weighed into the discussion again, this time in the Agriculture, Rural Development, Food and Drug Administration, and Related Agencies Appropriations Bill, 2012. The Committee report on the bill includes instructions to the Department of Agriculture “to ensure the FCC is aware of these concerns and to work with other Federal agencies, such as the Department of Defense and the Department of Transportation, to address them” (page 4; House Report 112-101). I suspect that we will see similar provisions in the DOT appropriations bill report when it comes out of Committee. It will be interesting to see what is included in the bill that provides funding for the FCC.



The article states that the most recent test results from RTCA, a nonprofit group that advises the FAA, “found that LightSquared's use of airwaves closest to the GPS spectrum would cause a ‘complete loss of GPS receiver function’ over large metropolitan areas”. Again there is no indication that the GPS timing signals used by various SCADA systems was specifically included in these tests, but a ‘complete loss of GPS receiver function’ does not portend well for SCADA systems.



The FCC is scheduled to receive a report this week from the technical working group that has been investigating the interference issue. The article notes that the following week we should see a request for public comments on the final deployment of the LightSquared system. I’ll certainly provide further information on that when it occurs.