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LightSquared Blames GPS Industry for Interference in Report

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Top message:  When all else fails... by crood   Jun 30, 2011, 10:06 AM

Replying to:  Re: LightSquared is right by WiWavelength   Jun 30, 2011, 11:16 PM

Re: LightSquared is right

by CellStudent    Jul 1, 2011, 12:04 AM

C'mon, CellStudent, if you are going to make that kind of damning assertion, I certainly hope that you have the material evidence to corroborate it. ... »

GPS device test results, which were also filed at the FCC today, show unequivocally that the interference is caused by the GPS device manufacturer's decision over the last eight years to design products that depend on using spectrum assigned to other FCC licensees.

The GPS receivers aren't staying within their band. They're listening to a 20 MHz wide band to catch a 0.5 MHz wide signal because they were too cheap to add an extra two or three orders to their filter designs for suppressing *radically* out-of-band transmissions! I ran the MATLAB simulations on it back in March or April when you and I spoke about this last and a 6th order analog filter was more than sufficient to provide 120 dB of rejection at the stopband edge of a GPS receiver with less than 1 dB loss at the passband edge.

The GPS makers have been completely banking on the fact that no one would ever use that spectrum for anything else, ever again. Globally.

L-Band isn't *just* good satellite spectrum- it's even more useful as terrestrial spectrum, because the higher microwave bands (like Ku and Ka) perform almost as well for satcom, but are practically useless for terrestrial omni propagation.

As for the bandwidth fragmentation, I'll agree that it's a problem, but the problem is policy and economy, not technology. ... »

AT&T bought AWS on the West coast, and Verizon bought AWS on the East coast. As a result, neither one of them can do anything with either block because the resulting handsets will only work across half the country. T-mobile bought AWS nationwide, so they're doing just fine. So fine AT&T wants all of it.

But if there were some (fair, viable, not Big Brother) way to force a spectrum swap so that one carrier gave up their PCS bands to the other and was gifted with AWS bands in return, (or something equally equitable) both companies could deploy and we'd have greater capacity, better service, and more comparable service providers to choose from nationwide.

The choice and availability of bands out there isn't the problem. The fact that different chunks of it in different bands are all owned by different companies in different regions is the problem. I wish there were an easy solution.

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