Do You Still Remember How to Read a Road Map?

You might want to refresh your map-reading skills, for a company called "LightSquared" wants to implement a nationwide wireless network. But their frequencies (which the chowderheads at the FCC let them have) are right next to the GPS frequencies.

So what you have are pretty weak signals coming down from satellites 12,500 miles up, which your GPS receiver will need to pick up through the noise broadcast by a transmitter that is virtually next door.

This is what your GPS receiver is looking for:

The GPS signal strength measured at the surface of the Earth is about –160dBw (1 x 10–16 watts), which is roughly equivalent to viewing a 25-watt light bulb from a distance of 10,000 miles.

That weak signal is because the satellites' transmitters have a signal strength of 50 watts. LightSquared's towers will have transmitters with a signal strength of 1,500 watts. GPS receivers would have to pick out those extremely weak GPS signals through that strong noise. The tests seem to be revealing that they cannot do it.

You may not know this: Modern agricultural equipment is very dependent on GPS. The folks at John Deere did some testing and found this: Deere receivers registered impact of and interference by the LightSquared signal as far away as 22 miles from a transmitter. Further, the company has found no practicable technical solution to the problem.

The FAA wants to replace its ground-based navigation aid system with GPS. Smaller airports had instrument approaches that used non-directional beacons (NDBs) for navigation. The FAA has been decommissioning NDBs and replacing the NDB approach procedures with GPS approaches. The LightSquared network would likely completely fuck those things up.

LightSquared's network would most likely screw with vehicle navigation systems. No doubt that they have bought off their share of congressmen. But between the airlines, agriculture, trucking, public safety, the car companies and the motoring public, my bet is that LightSquared is going to lose this fight.