[time-nuts] Agilent appnote
kirbybq at bellsouth.net
Mon Jul 25 14:03:24 EDT 2005
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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