In message <[EMAIL PROTECTED]>, Brooke Clarke writes: >Hi David: > >There's an appendix in the Stanford Research manual for the PRS10 Rb >oscillator that explains how to make 1,000 measurements each second and >thus get 1 ps accuracy every second. It involves using a precision >external clock into the SR620 and connecting the Ref Out (1 kHz derived >from the internal or Ref oscillator) into the External Gate input. The >Start and Stop signals need to be something like 10 MHz, or probably any >frequency at or above 1 kHz. And the gate is used to enable a >measurement 1,000 times per second.
I do this all the time with my HP5370B. Recently, after I wrote a GPIO driver for FreeBSD, I have managed to get it to spit out "binary format" timestamps, so now I can make it take 5000 measurements per second (with 20ps resolution and about 50ps noise) and get all the readings onto my computer, not just the average/stddev. I've been playing with doing FFT's of the samples and I belive I could clearly see the modulation frequency on my old Rb unit, but I never really found time to play a lot with it. -- 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
