In message <[EMAIL PROTECTED]>, Peter Vince writes: > I have seen something similar with my 53132A. I was checking >on the delay variation of an amplifier distributing 10 MHz, and >noticed a regular sinusoidal pattern, about a third of a nanosecond >peak-to-peak, with a period of about 70 seconds.
Almost any kind of interference will cause such anomalies and the closer the frequencies are to a multiple of each other, the longer the period will be. It is quite common for the frequency difference between the counters internal X-tal and the measued frequency to show up like that once you start to measure down in the nanosecond end of things. The HP5370 has a rather heavyhanded piece of electronics that eliminate this effect with a jitter based approach and as far as I have been able to measure, it works. "normal" counters don't have this, as they are not designed to measure in that domain of disturbances. The easiest way to determine if this is indeed the problem, is to feed the counter an external frequency which can be varied a bit up and down. If the period of the artifact changes accordingly: QED. -- 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] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
