Howie DeFelice wrote:
"I bet (a small bet anyway) my cell phone carrier doesn't save receive frequency data accurate enough to determine what direction I am driving though."
You are probably right since the doppler shift is pretty small ( at least I hope it is :) ) on a cellphone. The satellite access is MA-TDMA so the burst timing and frequency offset need to be tracked. This is a useful performance metric when troubleshooting connectivity issues in a big network.
- Howie AB2S
If my math is correct, doppler shift for a car driving 60mi/hr directly towards a non-moving cell tower (not always a safe assumption in California) would have a Doppler shift of about 90 hz, assuming a cell frequency of 1 ghz. There's probably considerably more variation in your carrier frequency due to temperature, power supply factors, and component ageing, though I suppose with time these could probably be determined and backed out.
Greg KO6TH