[time-nuts] Measuring frequency difference

WarrenS warrensjmail-one at yahoo.com
Sun Feb 7 23:42:32 UTC 2010


John Green said:
> "The thing that surprised me was how much a TBOLT's  [phase]  moved around 
> compared to my Z3801."
    That will be the case if  you are using the Tbolt's default tuning 
values.

ws

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[time-nuts] Measuring frequency difference
John Green wpxs472 at gmail.com

I started out using an oscilloscope and comparing OCXOs to my Z3801 GPSDO.
Later I used it to compare an LPRO 101 to the Z3801 and finally, a TBOLT. I
later acquired a Racal 1992 which makes things a little easier but no more
accurate in my opinion. If you are looking at frequency difference or
frequency drift, and not stability, either of these methods and a stopwatch
will get pretty good results. It took me a couple of days to get an LPRO
adjusted so that I saw one cycle slip every few hours. It takes patience.
The thing that surprised me was how much a TBOLT moved around compared to my
Z3801. Though it stayed within one cycle because it was "phase locked", it
jumped around a good bit while the LPRO just slowly slipped in one direction
or the other.





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