From: <[EMAIL PROTECTED]> Subject: [time-nuts] SRS SR620 External Source Issue -- Help Request Date: Wed, 21 Feb 2007 17:57:22 -0500 Message-ID: <[EMAIL PROTECTED]>
> I have an SR620 counter that I set up with a Z3801A as an external reference. > If I put a bnc T connector at the output of the Z3801A and use two equal > length bnc cables, one to the ext. ref input on the back and the other to > channel A then do a frequency measurement, I get a mean that is about .0015 > Hz below 10,000,000.0000Hz. > > Does any know why this might be happening? I would expect it to read > 10,000,000.0000 exactly give or take a couple on the last digit. The first thing that sprung to my mind was maybe some form of mathematical error in the software. There might be some other form of error such as non-linearity in interpolators, but that should not show up as a frequency error like that. It seems strange. There is really two very nasty tests you can do: 1) Measure with the time-base time on one or both channels, at various delays. 2) Measure a stable source which is just slightly off the time-base in frequency either in one channel or time-base on one channel and other source on the other. This really reveals "interesting" behaviours, such as how one channels signal affects the timing of the other. Cheers, Magnus _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
