New reports, citing a draft version of test results, say that LightSquared 4G LTE service caused "harmful interference" to the vast majority of GPS receivers used in the tests. These latest tests echo earlier ones that showed much the same result. In the latest results, we see that an alarmingly high number, 75 percent, of GPS units tested showed interference.
The tests were results conducted from Oct. 31 to Nov. 4. The draft seen by Bloomberg says that "millions of fielded GPS units are not compatible" with the planned LTE service.
The draft said, "LightSquared signals caused harmful interference to majority of GPS receivers tested. No additional testing is required to confirm harmful interference exists." Federal official will be reviewing the results in a meeting next week of U.S. officials reviewing the LightSquared proposal.
LightSquared, based in Reston, Virginia, has proposed a high-speed mobile Internet service using 40,000 base stations. Its service would operate in frequency spectrum previously reserved mainly for satellites, which is where the problem lies: it is near the frequencies used by GPS devices.
As a remedy, LightSquared has proposed operating at a lower power than the level used for the testing. Martin Harriman, executive vice president of LightSquared, said in an interview the that company believes that by using lower power it could limit interference to only about 10 percent of devices.
Harriman also issued the following statement regarding the leak of the draft report. "By ignoring this commitment by LightSquared [of lower power], this conclusion is erroneously based on estimated power levels that are up to 15 times the levels guaranteed by LightSquared. This breach attempts to draw an inaccurate conclusion to negatively influence the future of LightSquared and narrowly serve the business interests of the GPS industry."
The FCC gave LightSquared preliminary approval for its network in January pending interference tests.
This round of testing included participation by the DoD and the FAA, as well as GPS makers Trimble Navigation Ltd. and Garmin Ltd., farm-gear manufacturer Deere & Co., and GM's OnStar unit. Federal authorities still have one more round of testing, to be conducted on high-precision GPS devices.
The National Space-Based Positioning, Navigation, and Timing (PNT) Systems Engineering Forum plans to present these results on Dec. 14 in Washington, DC.