[time-nuts] Thunderbolt Loop Damping

Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Jul 7 22:14:58 EDT 2008


Tom Clifton wrote:
> The manual doesn't give much direction on tweaking the disciplining parameters.  Also, not having anything better to compare results to, I'm pretty handicapped.  Has anybody done any tweaking and perhaps can offer any suggestions?  
>
> Over the weekend I was able to get a GPS antenna on the roof coupled to the receiver in the basement by using an abandoned run of RG6 (Thanks Direct-TV! - The AT&T U-Verse doesn't fade during storms...)  Logging of the 10mhz shows it stays pretty much under 0.05ppb.  The Excel graphs are easy to generate, but not easy to use if that makes sense.  Limited to 32k datapoints per graph and very difficult to zoom in on.
>
> Also, Is anybody else as confused as I am by negative ppb numbers???  is 0.00ppb the 10x-11 "baseline" so that -0.01ppb is really 0.009ppb?
>
> Tom
>
>   
Tom

Surely the ppb measure just reflects the measured frequency error 
(actual OCXO frequency - 10.00000000000000000000000MHz ) in parts per 
billion, so a -ve ppb just means the sign of the error has opp0site that 
for a +ve ppb number.

Bruce




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