[time-nuts] GPS Modulation and 10 MHz Delay Lock

Magnus Danielson magnus at rubidium.dyndns.org
Wed Oct 3 20:17:43 EDT 2012


On 10/03/2012 03:38 PM, paul swed wrote:
> I think it was this thread.
> But the actual chip rates derive from a 10.22999999543 clock.
> We call it 1.023 Mhz but its not. In time-nuttery it matters.
> Doesn't that make the use of the signal a bit messy?

Nope. You missed the point of this off the mark is to compensate for the 
relativistic frequency shift that is occuring so the GPS clock at launch 
is at this rate, but when in orbit it will run a little faster, so this 
rate will match up better. Then, the remaining error is corrected for in 
the broadcast model so this first degree approximation will just get 
that decently into range.

Check ICD GPS 200D.

Cheers,
Magnus




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