[time-nuts] Disciplining Rubidium
Bruce Griffiths
bruce.griffiths at xtra.co.nz
Thu Apr 24 23:04:33 UTC 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.
>
>
Jim
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
oscillator.
Correction of the ionosphere propagation delay correction can take
advantage of the difference between the ionosphere's group and phase
velocities.
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.
Bruce
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