[time-nuts] Data collection cycle -- multiple sources to one counter?
Poul-Henning Kamp
phk at phk.freebsd.dk
Sun Jun 19 07:56:56 UTC 2005
In message <42B4BE4F.5030802 at febo.com>, John Ackermann N8UR writes:
>I want to monitor all my atomic devices over the long term against GPS.
>Rather than devoting one counter to each source and gathering a lot more
>data than is useful, I'm going to use a GPIB-controlled coax switch to
>route the 1pps from each source into the counter START input. That way
>I can alternately read each source for X minutes against GPS.
>
>My question is whether there is an optimum "X" for the time to dwell on
>each source.
What you really need to look at is how often you revisit each source
so that you don't get roll-over ambiguities.
Switching too fast will also wear out your relays, and that is one thing
to be wary about buying automation multiplexers on eBay: A lot of what
is available is there because relays started being unreliable.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at 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.
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