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
_______________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
