[time-nuts] HP 5328A Divider / Timebase Output performance

Bob Camp lists at rtty.us
Thu Mar 18 01:41:38 UTC 2010


Hi

You could time stamp the replies against the PC's clock. That would at least let you spot drop outs.

Bob


On Mar 17, 2010, at 9:32 PM, John Miles wrote:

> 
>> OK, so I tried this myself. A sloppy setup but never the less... The
>> CNT-90 time-base output via a T-connection on B-channel and then over to
>> the A input of the HP 5328, selected START A and then the T.B. OUT over
>> to CNT-90 channel A. At 100 kHz setting on the HP 5328, the TI A->B
>> measurement on CNT-90 shows some jitter, but RMS jitter is below 400 ps
>> at least and ADEV readings somewhat below that.
> 
> There's one other potential error source in Bert's case that might make his
> results look a bit worse than they really are.  TI addresses the 5370 in
> talk/listen mode, and I've noticed that it can sometimes get into a state
> where the counter appears to skip every other reading.  I've only seen this
> happen with 1-pps sources driving both channels but it could conceivably
> happen on a 10 MHz test as well.  The result would be 2 seconds' worth of
> noise/drift between readings instead of one, which would artificially make
> the graph look a bit worse.
> 
> So if the counter's display seems to change only after every other START
> cycle, that could be happening.  The next test version will allow the
> counter to run in talk-only mode with arbitrary measurement periods, which
> should avoid this behavior completely.
> 
> -- john, KE5FX
> 
> 
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