[time-nuts] HP 53131A question
Magnus Danielson
magnus at rubidium.dyndns.org
Sat Nov 22 14:57:05 UTC 2008
iovane at inwind.it skrev:
> Hi all,
>
> I'm planning to use a HP 53131A for phase measurements.
> In a limit case, just to understand, suppose that I'm
> reading, say, 100 degrees, and the next reading gives again
> 100 degrees, but meanwhile the signal under test jumped 360
> degrees. Is there any way to detect such a case?
No. Not really. The counter makes a +/- TI measurement between channel A
and B and also measures frequency on one of them. The individual count
on the two channels is lost and thus the slip information. If you divide
the signals down by say 10, then a signle cycle slip on the original
signal would show up as a 36 degree shift in reading, while a 10 degree
shift on the signal would be displayed as a 1 degree shift on reading.
The dividers would hold the state which you don't get directly. Some
counters allow for simultaneous time-stamping and event counter
recording of A and B channels. Those counters safe enought state to
provide phase measurement (through time stamp) and slip difference
(through event counters). You are interested in absolute phase, so that
is what you want to do.
Cheers,
Magnus
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