Hi The blue trace is what a spur (FM noise tone) looks like when measured as ADEV. As Charles has pointed out several times it’s pretty easy to get these sort of issues with low levels of “interference”.
Bob > On Aug 1, 2015, at 5:49 PM, Bob Stewart <[email protected]> wrote: > > Hi Poul, > Here's an example of what I'm talking about. See description and notes. The > blue trace is the one using the clock in the 5370A. The other tests match > pretty closely down to around 60s or so. > > http://evoria.net/AE6RV/5370A/Test1.png > Bob > > From: Poul-Henning Kamp <[email protected]> > To: Bob Stewart <[email protected]>; Discussion of precise time and frequency > measurement <[email protected]> > Sent: Saturday, August 1, 2015 4:10 PM > Subject: Re: [time-nuts] Data Collection for Allan Deviation > > -------- > In message <[email protected]>, > Bob Stewart writes: >> Hi Poul, > >> "0) Make sure that the counter does not get its reference frequency >> from any of the input signals." >> >> Does your rule 0 hold if one of the input signals is a Cs standard? >> I believe I've posted in the past that the ADEV from 1 tau to 100 >> tau is a bit noisy if I use the internal 10811 to clock the 5370A. >> I noticed the same on my 5335A. > > For me it is a rule of principle: If the HP5370 is clocked from the > same source I'm measuring, I can have no expectation of a well > behaved noise from the triggers. > > The "noise" you saw is probably exactly that: Overly optimistic > results if you clock the counter from one of the DUTs > > > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > [email protected] | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
