LightSquared admits it will knock out 200,000 sat-navs
Unholy row at FCC: GPS industry predicts rain of planes
"The results of the initial tests haven't been shared (we have asked for a copy, and the PDF summary contains details of the revised testing), but LightSquared claims all the tests show definitively that it isn't leaking transmissions into the frequencies in which GPS is supposed to operate (which start at 1559MHz). Instead the GPS receivers "have been deliberately or, sometimes, inadvertently, designed ... with the assumption that there would be no adjacent-band terrestrial transmissions".
GPS receivers straining to pick up the weak satellite signal are listening on too broad a band, according to LightSquared, which is why they have problems with when LightSquared transmits on its upper band despite there already being a significant buffer (the now-not-to-be-used band lies at 1545.2-1555.2 MHz). So LightSquared said it will move to 1526-1536MHz for its launch, and claims that the independent testing in this band shows that smartphone and consumer GPS will all work and that only the 200,000 of so high-precision devices will have problems.
The GPS industry is, of course, having none of it. The Coalition to Save Our GPS sees no reason why they should be forced to change their designs, and contends that LightSquared's estimate of 5 cents per device for better filtering is entirely untested and no better than a guess. They also point out that LightSquared's new plan only delays the use of the upper band, and is based on (what they consider) a flawed assumption that the GPS industry will clean up its accuracy of reception.
Rather more hyperbolically, the Coalition also claims that that planes will fall from the sky and that allowing LightSquared to deploy will cost the US economy $96bn annually."
More: theregister.co.uk
Jim |
