LOS ANGELES (KNX 1070) — A planned nationwide 4G broadband service threatens to cause “widespread, severe GPS jamming,” according to a recent GPS industry study and reported by KNX Newsradio.

Millions of GPS units are now in our cars, boats, planes and even smartphones.

A company called Lightsquared is hoping to begin testing the service this fall using 40,000 transmission towers.

Jeffrey Carlisle, an executive vice-president at Lighsquared claims the GPS study, done by GPS manufacturer Garmin, is faulty, because the correct filters were not used. But he concedes there may be some interference to GPS signals which, in his view, may require modification to some exiting GPS units.

Garmin’s Ted Gartner counters that his company has been unable to obtain the filters from Lightsquared, but doubts they would change the outcome of the study.

Garmin’s Ted Gartner Expresses Concern About Planned 4G Service

The FAA and U.S. military have now expressed their concern.

KNX 1070’s Charles Feldman Reports

An FCC spokesman tells KNX that “we recognize there is a potential for interference; it’s a concern.”

The FCC has ordered new tests to be conducted and says Lightsquared will not be allowed to start its 4G service until all parties involved are satisfied.

(©2010 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

Comments (9)
  1. Val barrett says:

    The magnetic reversal will also mess up GPS.

  2. Joe Dionne says:

    GPS doesn’t use magnetism.

  3. DecentDiscourse says:

    Oh, God. This is journalism? A few things to note. Not surprisingly, the comments provided to the FCC which raised this issue are from Garmin, the U.S. GPS Industry Council and Trimble Navigation. What’s also missing from this report is that the 4G company building this network, LightSquared, says any problem if it occurs comes from GPS receivers which are LOOKING INTO THE WRONG ADJACENT FREQUENCY BAND, not from interference caused by their system transmitting in its allocated frequency range. It’s also important to note that not all 4G systems are involved, so it’s not Verizon, or Sprint or T-Mobile. This is a new company operating in a different band. Finally, its important to note that the paper written by Garmin is based on simulations, not actual testing and that they tested only two devices. I’d love to know if higher quality GPS units with properly designed receivers would ignore adjacent channel signals and not be affected.
    I’m not discounting the simulation, but I’m not buying it hook, line and sinker either. You can see the whole 8 page “study” at http://www.gpsworld.com/gnss-system/signal-processing/lightsquared-jamming-report-11030

    1. Mike says:


      It’s hard to make filters that selective, and the way ALL high accuracy GPS receivers work is to look at the signals at the outer sides of the band. That’s why the impact on the FCC certified Garmin receiver is significantly worse then on the cheap consumer device.

      This spectrum is supposed to only be used for satellite communication, not 4G towers, for just this reason. LightSquared found a loophole in what would otherwise have been a very lengthy process to re-purpose that chunk of spectrum, followed by public bidding. LightSquared got the spectrum for free, and is trying to use it in the same was as spectrum that another cell phone company would have paid a large amount of money for.

      The RF experts I know are skeptical that LightSquard will have a filter good enough to prevent interference with GPS. No one has been able to get any information out of LightSquared yet.

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