Checksum: 53378
Path: utzoo!utgpu!dennis
From: dennis@gpu.utcs.utoronto.ca (Dennis Ferguson)
Date: Wed, 31-May-89 02:03:48 EDT
Message-ID: <1989May31.020348.7540@gpu.utcs.utoronto.ca>
Organization: Mechanical Engineering, University of Toronto
Newsgroups: comp.dcom.lans
Subject: Re: Radio Time Clocks
References: <895@osf.OSF.ORG> <3086@daisy.UUCP> <2767@csccat.UUCP> <600@lzaz.ATT.COM> <13437@ut-emx.UUCP> <1989May27.222428.4127@utzoo.uucp> <1970@ccncsu.ColoState.EDU> <16468@bellcore.bellcore.com> <1989May30.224116.2101@gpu.utcs.utoronto.ca> <26174@ames.arc.nasa.gov>
Reply-To: dennis@gpu.utcs.utoronto.ca (Dennis Ferguson)

In article <26174@ames.arc.nasa.gov> medin@cincsac.arc.nasa.gov (Milo S. Medin) writes:
>Actually, our PSTI (now defunct) clock seems to be very happy to keep
>a steady lock on WWV from here in northern California.  It does have
>an external antenna, but has no problems maintaining sync...

You are right, I got carried away.  If you are close enough and/or have
a good antenna a radio clock can do very well.  Even the PSTI clock is
reputed to hang on longer than it should, however (I am assuming you know
the clock maintains constant sync by having measured it against other
clocks.  Having the in-sync LED on the front of the thing on all the
time may as likely be a symptom of a problem as it is an indication that
no problem exists).  Actually, "close enough" doesn't seem to be right
either.  I've had to invest in a fair amount of antenna wire to get
CHU fairly noise free, I am told that 300 kilometers is actually a little
too close and that the better signals are skipping over my head.

I still think that if you want a source of time you can poll once in
a while and get guaranteed reliable time, your HF radio clock may
disappoint you from time to time unless you are in a location which
is advantageous geographically, or the algorithms the clock uses to
process the time are very good.  In the latter case I think I'd rather
have those algorithms running somewhere where I can see them and fix
them when they do break.

Dennis Ferguson