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 <p...@phk.freebsd.dk> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Saturday, August 1, 2015 4:10 PM Subject: Re: [time-nuts] Data Collection for Allan Deviation -------- In message <1925117252.232793.1438455428192.javamail.ya...@mail.yahoo.com>, 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 p...@freebsd.org | 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.