[ntp:questions] Offset Average (Normal)?

Alby VA albyva at empire.org
Tue Mar 13 02:34:39 UTC 2012


On Mar 12, 9:57 pm, unruh <un... at invalid.ca> wrote:
> On 2012-03-13, Alby VA <alb... at empire.org> wrote:
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> > On Mar 12, 7:21?pm, unruh <un... at invalid.ca> wrote:
> >> On 2012-03-12, Alby VA <alb... at empire.org> wrote:
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> >> > ?If your offset is between -400 to +600 ?s (microseconds), would you
> >> > consider that Good, Bad, or Average?
> >> > If it is less than Good, could something be tweaked to improve it?
> >> > ntp.conf changes? cable changes?
> >> > or I'm just SOL?
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> >> What operating system? What is your server (network, wristwatch, gps,
> >> pps?) For PPS you should be able to get +- 1us. for a server in Moscow,
> >> +- 1ms.
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> >> > Stats
> >> > --------
> >> >http://godzilla.empire.org/
> >> >http://www.pool.ntp.org/scores/63.251.89.141
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> >> > assID=0 status=0115 leap_none, sync_atomic, 1 event,
> >> > event_clock_reset,
> >> > version="ntpd 4.2.... at 1.2349-o Mon Feb 20 22:00:33 UTC 2012 (1)",
> >> > processor="amd64", system="FreeBSD/9.0-RELEASE", leap=00, stratum=1,
> >> > precision=-19, rootdelay=0.000, rootdisp=1.082, refid=PPS,
> >> > reftime=d308de90.7e20860b ?Mon, Mar 12 2012 16:44:00.492,
> >> > clock=d308dec4.6a2aacac ?Mon, Mar 12 2012 16:44:52.414, peer=9406,
> >> > tc=4,
> >> > mintc=3, offset=0.081, frequency=-24.987, sys_jitter=6.771,
> >> > clk_jitter=0.003, clk_wander=0.004
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> >  The Stratum 0 devices is SureGPS and its running on FreeBSD as the OS
> > and AMD for the chip.
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> OK. Is it using its PPS or just the nmea sentences? If the latter then
> 100us is very good for a jitter. If the former it is very bad. (My
> offsets on a chrony machine are standard deviation of about .8us, and on
> an nptd machine, about 2us.-- using Linux and a serial interrupt with
> pps_ldisc/pps_core driver on the former, and a parallel port interrupt
> routine on the latter.
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> If you are just using the sure nmea sentences, then you are getting far
> better than expected. (man ms is more typical from SureGPS nmea only)
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> > FreeBSD godzilla.empire.org 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue
> > Feb 21 22:13:35 EST 2012  amd64




Yeah it is using PPS.  NOTE:   refid=PPS


-Alby



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