I don't think any of the current drivers in NTP will do the right thing for
this project.
The PPS driver is a bit tricky. It needs help to figure out which second a
pulse corresponds to. I think there is a filter in there to reject samples
that are too far off from what it thinks is a second boundary.
Yeah, I didn't check the list of NTP drivers to see if one had
been written already, or if an existing one could be made to
work with a few lines of code. How does NTP handle the cases
where an accurate 1PPS is available but the time itself isn't?
This would be the case for most cesium or OCXO references,
or maybe even some GPS 1PPS references.
One could also use an external divide-by-60 counter to convert
60 Hz to 1 Hz -> DCD. You could get clever and send 60 Hz
to Rx as described earlier and 1 Hz to DCD on the same, or
another port, for use by the NTP PPS driver.
Or, use a software divider: let the user program that's reading
the 60 bytes/second pulse DTR once every 60 bytes, tie this
to NTP's DCD pin and -- the PC is generating its own 1PPS.
My thought was simply that since NTP is fairly well-known, it
might make a nice demo to see a power-line-sync'ed PC run
for a couple of weeks before the TEC experiment, and then
during the TEC experiment.
/tvb
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