[ntp:questions] Running ntpd with 1 PPS precision signal only

unruh unruh at wormhole.physics.ubc.ca
Wed Oct 5 16:31:51 UTC 2011


On 2011-10-05, alexandros kampolis <elefteros.skopeftis at gmail.com> wrote:
> Most (if not all) use a GPS receiver as a precision time source. This
> includes the NMEA messages and the 1 PPS output.
>
> The question is: can i use the GPS receiver configuration but replace
> the receiver with a precision 1 PPS source? I have a quartz frequency
> standard that is able to output 1 PPS pulses and i want to use this
> instead of the GPS receiver (which i do not have).
>
> I'm asking this because i do not know if ntpd requires both the NMEA
> messages and the 1 PPS pulses to work correct (or to work at all).

Yes, it can be done. Eg the shm driver and the shmpps userspace to make
sure that your system has settled down so it is within .25 ssec of the
correct time, since pps on its own cannot tell you which second it is
that it exactly gave you the pulse for. Ie, you do not something else to
give you the seconds. gps, network ntp servers, whatever.




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