[time-nuts] Fundamental limits on performance
ik1odo at spin-it.com
Sun Sep 13 12:28:45 UTC 2009
At 06.51 13/09/2009, you wrote:
>In the deep space exploration biz, we've been talking about time and
>frequency transfer between spacecraft. It's pretty easy to figure
>out what the "Shannon limit" for the link between the spacecraft is
>(given power transmitted, antenna gain, etc... And with coding, we
>get within tenths, if not hundredths of a dB of the limit)...
>So, if I have a clock of some performance on Spacecraft A, is there
>a "simple" way to say how well I can do transfering that to Spacecraft B?
I think you have to translate your arbitrary time resolution in a
certain number of bits. I don't have the mathematical background to
develop it further, but it should be feasible. Those that developed
the GPS in the sixties should had it very clear :-) - here too you
have great limitations in throughput (50 b/s if I remember it well),
and the time sync is obtained by code despreading.
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