[time-nuts] Disciplining Rubidium

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Apr 24 19:04:33 EDT 2008

Jim Lux wrote:
> Other uncertainties (multipath, ionosphere, phase center movement 
> with look angle, etc) are of that general magnitude as well, so even 
> if your little receiver could put out a 1pps with 1ns accuracy, the 
> other parts of the system are worse.

Receiving antenna phase centre movement will only be a few cm not meters.
Also the phase centre position is highly repeatable and once calibrated 
can easily be corrected for.
Even the phase centre movement of the SV transmitting antenna (typically 
a helical antenna array) can be modelled.

Multipath has a relatively small effect on a carrier phase disciplined 

Correction of the ionosphere propagation delay correction can take 
advantage of the difference between the ionosphere's group and phase 
Only a single frequency receiver is required for this.

However generating an accurately positioned PPS pulse is another matter 
entirely as code phase data is required.


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