We’ve been talking about the battle between LightSquared and the GPS industry. The heart of the problem is that the spectrum for 4G network and the GPS signals are right next to each other and compared to GPS signals 4G signals are way way stronger, possibly causing interference.
In a report published June last year did indeed say this was the case.
“For the originally defined LightSquared spectrum deployment scenarios, GPS-based operations are expected to be unavailable over entire regions of the country at any normal operational aircraft altitude.”
So LightSquare’s solution was to use the dark orange band to the left to stay as far from regular GPS receivers as possible. This combined with better management of emissions from transmitter would save the sat nav systems used in aircrafts and cars.
However the super accurate high end GPS receivers are still very susceptible to interference because their radio frequency filters are very “liberal” and sometimes the augmentation signals used by them are actually transmitted from frequencies in the mobile satellite band.
I guess the problem is actually receivers not sticking to their allowed frequency since the receiver side of things is not really regulated by FCC.
However if you want more technical insight do read up on this article too.