The signal is encrypted at the satellite. Military receivers can decode this encryption to get better accuracy , but not 1 cm accuracy. My ship was issued a cheap civilian GPS receiver during the gulf war, as were many others. They revolutionized navigation but I can confirm that they did _not_ have 1 cm accuracy even with the encryption turned off at the satellite.
Another way to defeat the encryption that was not mentioned here is to use a ground-based GPS transmitter of your own construction to calibrate the satellite signals. There was talk a while back of using them to assist in automatic aircraft landing systems at airports since they would be a lot cheaper than the alternatives that were supposed to be under design.
Need I mention that such a system would be a prime target for jamming?
Slashdot Mirror
The signal is encrypted at the satellite. Military receivers can decode this encryption to get better accuracy , but not 1 cm accuracy. My ship was issued a cheap civilian GPS receiver during the gulf war, as were many others. They revolutionized navigation but I can confirm that they did _not_ have 1 cm accuracy even with the encryption turned off at the satellite.
Another way to defeat the encryption that was not mentioned here is to use a ground-based GPS transmitter of your own construction to calibrate the satellite signals. There was talk a while back of using them to assist in automatic aircraft landing systems at airports since they would be a lot cheaper than the alternatives that were supposed to be under design.
Need I mention that such a system would be a prime target for jamming?
Unless your CPU is made of a few atoms floating in a rarefied vacuum I doubt this technique will help much.