[time-nuts] Progress of my HP Z3801A

Hal Murray hmurray at suespammers.org
Thu Aug 31 02:05:16 UTC 2006


> Any real ideas on how to make it work in coordination with NTP?

ntpd has a lot of logging.  If you turn on clockstats you will get the info from your refclocks, mostly a line with a timestamp and the raw data, like this:
  53978 3319.033 127.127.26.1 T2200608310055203000039
  53978 3383.033 127.127.26.1 T220060831005624300003E
  53978 3446.033 127.127.26.1 T2200608310057273000042
Normally, they are collected every 64 seconds.

There is an option for the driver to record the whole info page whenever it grabs a time sample.  I'd have to check the documentation to find out how to do it.  It should be easy to find.  Beware.  It might use a lot of disk space.  (24x80 bytes every 64 seconds.)

It shouldn't be very hard to write some code to extract the latest info from the end of the file.  64 seconds is probably often enough if you want to track satellites by hand.

I didn't want to use up that much disk space, so I hacked the driver to ask for and record the  items I was interested in.  I get things like this in the log file:
  53978 3446.168 127.127.26.1 +765465 +1.51E-008 +4 +3.75259E+005,0 +7.7E-006,0
Those are the responses to:
    :DIAG:ROSC:EFC:ABS?
    :PTIME:TINT?\r*CLS
    :GPS:SAT:TRAC:COUNT?
    :ROSC:HOLD:DUR?
    :ROSC:HOLD:TUNC:PRED?

The CLS on the :PTIME:TINT? is there to recover from the case where it generates an error.

If anybody is interested, you can have a copy of my code and/or I'll work on getting it into the release.  (I'll be off the net for ~10 days, so don't be surprised by a lack of response.)

There is some case where it gets confused and writes out a bogus line of info so the graphs get screwed up.  I haven't seen it often enough to debug.  It's probably something like when the Z3801A gets restarted while ntpd is running.



An alternative approach would be to use 2 serial ports, and duplicate the RX data and PPS signals on the cable to NTP.  Then modify the non-ntp code to also send a :PTIME:TCODE?.  ntpd will grab the answer to that and ignore everything else.




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