LightSquared's proposals not viable, general says

LightSquared’s proposed wireless broadband network “cannot exist” with the U.S. military’s Global Positioning System technology, Air Force Space Command Commander Gen. William Shelton reiterated Sept. 20, reports Philip Ewing at DOD Buzz.

Even though LightSquared’s alternative proposal for its network would move its signal farther away from GPS, it would still squelch the harmonic frequencies that precise receivers use, Shelton said during a question-and-answer session and subsequent discussions with reporters at the Air Force Association trade show in Washington, D.C.

As for the idea of installing “filters” to protect GPS receivers, the concept is cost prohibitive, Shelton said, adding that the only viable solution is having the FCC move LightSquared’s network up or down the spectrum.

Reader Comments

Tue, Sep 27, 2011 RC

Lightsquared has been trying to force the wrong service into spectrum intended for other purposes. Their crying over "what they paid for" is a dishonest response to getting caught.

Tue, Sep 27, 2011 DEFENDER OF THE FREE WORLD

Hey, I have a novel idea, how about Lightsquared change there operating frequency instead of the other way around. MGRS system only controls most of the western world, people have no idea ll of the second and thrid orders effects that their life would have if the system is disrupted in any way.

Mon, Sep 26, 2011 RobertGPS

Mr. Diepold, You are either technically incompetent to make this judgment or you are being disingenuous. The issues lies in the overwhelming differences in the signal levels between the two systems. The GPS signal is received at a level of -130dBm at the surface of the earth. The Lightsquared ERP can be as high as +62dBm (that’s 192dB delta – i.e. the lightsquared signal is 15,484,932 trillion times stronger). It would be like trying to see a faint star far off in the galaxy while looking directly at the sun. Imagine if Lightsquared were allowed to proceed and 10 years from now, once the system is fully fielded and 100’s of millions of applications are deployed, indeed nearly every aspect of our economy has become dependent on it (as we have on GPS), then all of a sudden the FCC approves the deployment of 40,000 transmitters that operate at 100MW and that is located only 16MHz away from the Lightsquared spectrum. This would render nearly every Lightsquared receiver unusable. Are you honestly telling me that Lightsquared would simply say, “oh well, we should have use better filtering?”

Thu, Sep 22, 2011 Ken Diepold Charlottesville, VA

IF the USAF would not allow their GPS to bleed into private spectrum then LightSquared would not be the problem. GPS exceeds the 1559 MHz limit of their operating range. LightSquared paid for 1559-1607 MHz band and GPS is the cause of the interference. The nissue is only for 1-2% of the LightSquared system, not drop dead as the naysayers say!

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