You may have a "bias" error. Try connecting 1 PPS to the start input
and stop input via equal length of bnc barrels or two very short
pieces of matched length cable. Run your measurements again - you mave
have to subtract the "bias" from your measurements to get a true reading.
Bria - N4FMN
Joseph Gray wrote:
That is two methods yes (you need to distinguish between phase-delay and
group-delay). However, considering that he was reading AP200-3 the
text giving
the reference is:
+/- Systematic Error
Magnus, your psychic ability is amazing :-) Yes, I was reading
AP200-3. I'm surprised that I can't find AP174-10 at Agilent, though.
Thanks to everyone for the helpful suggestions. I had actually done a
simple measurement of a cable with my 5370A. I saw this method
mentioned on John Ackerman's site. The results I came up with were a
bit longer than the actual cable. I wasn't sure if this was due to the
BNC connectors and tee adapter, or some error in my measurement.
Here is what I got with the average of 100 measurements: Mean = 19.197 nS
I calculated the mean value times C (299,792,458 m/S) and then by the
velocity factor (Beldin RG-58AU is .66, right?). This comes out to
12.47 ft.
The coax I was using is 12 ft long.
As for the phantom appnote, I would still like to see a copy. It may
provide further insight into the process.
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