On 2021-06-09, ProGeek <progee...@gmail.com> wrote: > On Wednesday, June 9, 2021 at 6:56:04 PM UTC+3, chris wrote: >> On 06/08/21 20:42, Andreas Mattheiss wrote: >> > Hello, >> > >> > just as additional source of information: I have a similar setup here >> > (ublox PPS into a proper serial port of a PC) and I see a stable offset of >> > -3 ms to 3 servers on the net (-3 ms to any of them). I'm using ntpd >> > though. >> > >> > Regards >> > Andreas >> > >> This is what I see at the ntp host here: >> >> chris@ntp-host:~ % ntpq -pn >> remote refid st t when poll reach delay offset jitter >> ====================================================================== >> o127.127.22.0 .PPS. 0 l 1 8 377 0.000 0.000 0.001 >> +192.9.200.168 .GPS. 1 u 10 64 377 0.193 0.001 0.054 >> *192.9.200.169 .GPS. 1 u 7 64 377 0.354 0.008 0.046 >> >> Using mini pc host with two network interfaces, internet and internal >> network facing. FreeBSD 12 with ttl pps into the serial port dcd line >> via a ttl to rs232 converter... >> >> Chris > this is what i see on sourcestats: > > 210 Number of sources = 7 > .- Number of sample points in measurement set. > / .- Number of residual runs with same sign. > | / .- Length of measurement set (time). > | | / .- Est. clock freq error (ppm). > | | | / .- Est. error in freq. > | | | | / .- Est. offset. > | | | | | | On the -. > | | | | | | samples. \ > | | | | | | | > Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev >============================================================================== > GPS0 12 6 176 -29.089 42.914 -8857us 1790us > SHM1 12 7 178 +0.000 0.010 -530ms 435ns > PPS0 12 7 178 +0.001 0.011 +3ns 445ns > blackmamba-g0.eff.ro 2 0 77 -0.005 2000.000 +501ms 4000ms > 188.213.49.35 9 6 184 -0.748 21.608 +492ms 721us > time.cloudflare.com 6 4 81 +1.162 9.574 +500ms 72us > time.cloudflare.com 14 11 168 +0.502 0.939 +500ms 42us > > if i get the results from PPS0 the offset is low, but is still reported high. > and also correspond with the external time servers.
Sorry but that is nuts. Your external sources are 500ms ( 1/2 sec) off from the internal ones. But that is probably because you told your system to screw up the internal sources. > > my settings are like this: > > # SHM(0), gpsd: NMEA data from shared memory provided by gpsd > refclock SHM 0 refid GPS0 poll 4 precision 1e-1 trust noselect offset 0.646 Why that offset? and why precision of 1e-1? > > # SHM(1), gpsd: PPS0 data from shared memory provided by gpsd > refclock SHM 1 refid SHM1 poll 4 precision 1e-3 lock GPS0 trust noselect > offset 0.5300 Why that offset? Also, why are you having both gpsd and pps0 delivering data? It is the same pps. And they fight each other-- when one interrupt is processing, the other one is locked out. This makes the accuracy of pps less than it should be (by a factor of about 10) Tell gpsd not to use the PPS. > > # PPS: /dev/pps0: Kernel-mode PPS ref-clock for the precise seconds > refclock PPS /dev/pps0 refid PPS0 poll 4 precision 1e-7 lock GPS0 trust > prefer delay 0.50 Why that delay? HOw about getting rid of all of the offset and delay stuff on your internal sources. > > something is off but i can't pinpoint what Sure is. _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
