[ntp:questions] What should the poll be for the shared memory driver (type 28)?

David Taylor david-taylor at blueyonder.co.uk.invalid
Mon Jun 17 18:11:47 UTC 2013

On 17/06/2013 17:12, David Lord wrote:
> I've used type-28 + radioclkd2 for many years with MSF and for a
> while with DCF. I've never set minpoll/maxpoll but it has always
> defaulted to 6, ie 64 sec. DCF has a phase shift second marker
> but is too distant for that to useful. When DCF reception was
> good the timekeeping was better than from msf (+/- 0.1 ms vs 1ms).
> As you mentioned above, type 28 refclock pages indicate the driver
> is polled by ntp at 1 second intervals (as from ntpd-4.2.5p138).
> David

Thanks, David.  I'm trying a poll of 4 now (16 seconds) as that will 
match the normal PPS/kernel method (and reduce the size of the log 
file).  Will watch the jitter and see whether it changes.  The 
GPS-derived PPS signal should be within 0.1 us, making the PC the 
limiting factor.
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