William Unruh <un...@invalid.ca> wrote: > On 2015-02-19, Rob <nom...@example.com> wrote: >> Miroslav Lichvar <mlich...@redhat.com> wrote: >>> On Thu, Feb 19, 2015 at 12:48:46PM +0000, Rob wrote: >>>> I am still finding out what sensor is best to use, we do have a room >>>> temperature sensor that has .1C resolution and is readable via snmp, >>>> and there are the usual sensors for board- and inlet air temperature. >>>> (and of course CPU temperature) >>>> >>>> It does not matter if it is only a course indication, the room temperature >>>> varies over a -10 .. 50C range (don't ask...) and a 1C resolution is not >>>> bad relative to that. >>> >>> In my tests using a sensor with 1C resolution it was barely useful >>> with NTP sources and 1024s polling interval. If the sensitivity is >>> around 0.1 ppm per degree, 1C resolution means the compensation >>> jumping the frequency in 0.1ppm steps. That's a lot, especially if you >>> compare it to the tracking skew with a refclock. >> >> Ok but of course we are using PPS and a 16 second polling interval. >> (or maybe the PPS refclock polls even faster although it displays 4 as >> the poll interval indicator) > > The shm refclock will get one pulse per second, and then average the > offsets over a 16 sec period after getting rid of the outliers.
I am not using the SHM refclock in those systems. _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
