sat-com (figured I better change the subject)
"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
My cellphone carrier can detect which direction my phone is pointed very accurately in a single location in my home. It shows on my internal mapping function and GPS is shut off. That to me means constant triangulation along with direction sensing within my android device...
If I'm in an accident that is good...if I do something illegal that is bad...
Not bad for finding north to orient satellite antennas though...
That to me is scarey in itself.
Roger WA1KAT
On 3/27/2014 4:17 PM, 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
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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
participants (3)
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Greg D -
Howie DeFelice -
Roger Kolakowski