[time-nuts] GPSDO TC & Damping
bruce.griffiths at xtra.co.nz
Sat Jan 10 00:57:25 EST 2009
Mark Sims wrote:
> The good Lady Heather's GPS Disciplined Oscillator Controller Program calculates and plots (also writes the results to the log file) ADEV and OADEV of the Thunderbolt's reported error estimates. My comparison of these "auto-ADEVs" to the values generated from a Tek DC5010 counter showed they agreed within a factor of two.
> Note that the DC5010 was measuring the Thunderbolt 10 MHz signal against a 1 MHz cesium reference. The data had to be massaged some where the phase rolled over (the DC5010 counter has a 5 nsec or so bogus zone where the time interval is wrapping). The counter was set up to calculate time intervals over 10 seconds (to get picosecond resolution) so ADEVs below 10 seconds were not available.
> What does the plot of ADEV vs tau look like when the Thunderbolt OCXO is
> unlocked and one just logs the Thunderbolt's own measurements of the
> phase and frequency errors.
> It should exhibit a minimum at a value of certain value of tau.
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Where these results obtained when the Thunderbolt OCXO was locked?
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