Maarten Wiltink wrote:
"Maarten Wiltink"<[email protected]> wrote in message
news:[email protected]...
"Nero Imhard"<[email protected]> wrote in message
news:[email protected]...
[...] A TXCO is a frequency source, and not
a time source. ntp's PPS drivers expect a time source. Each pulse
should be precisely aligned with the start of a UTC-second.
If your PPS pulses are not aligned with UTC, you cannot use the signal
as a time source!
Not quite true. If you where in the second the pulse falls, you can.
Curses. If you *know* where in the second the pulse falls, you can.
Indeed.
Really high-perf clock sources, like the Motorola Oncore UT+, have
configuration commands that allows you to offset the PPS from the top of
the second, on the assumption that many other programs will tend to wait
for that moment in time in order to do som processing:
By moving the PPS pulses a few hundred ms to the side, the host cpu is
more likely to be idle at the time of the interrupt.
(The Oncore driver will of course adjust the received timestamps by the
same amount, so NTPD will never notice the offset.)
Terje
--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
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