[ntp:questions] Performance?
dhavey
dhavey at gmail.com
Mon Dec 29 20:02:24 UTC 2008
On Dec 24, 8:09 am, k... at uiowa.edu (David R. Andersen) wrote:
> I have a Garmin 18LVC GPS set up at 9600 baud and emitting the GPGGA
> sentence. PPS is connected to pin 1 of the DB9 (DCD pin). I typically
> get 1-2 microsecond jitter with this setup and FreeBSD O/S. ntp.conf
> statements to enable this clock are:
>
> server 127.127.20.1 mode 18 prefer # mode 2 enables $GPGGA operation,
> mode 16 enables 9600 baud operation
> fudge 127.127.20.1 time1 0.000 flag2 1 # flag2 0=pps edge on assert,
> 1=pps edge on clear
>
> The server mode 18 parameter does two things - enable GPGGA operation
> and enable 9600 baud operation. Fudge flag2 should be set or cleared
> depending on your PPS signal. time1 should be set as appropriate for
> your system. Also, be sure to set symlinks as appropriate in /dev so
> that the clock driver can find the serial port. With FreeBSD I have
> /dev/gps1 symlinked to /dev/cuad1. With linux, /dev/gps1 should be
> symlinked to /dev/ttyS# where # is the number of the serial port you are
> using.
>
> Dave
>
>
>
> dhavey wrote:
> > On Dec 22, 5:41 pm, hal-use... at ip-64-139-1-69.sjc.megapath.net (Hal
> > Murray) wrote:
>
> >>> I'm using Garmin LVC's. I used the windows config program on one of
> >>> them and changed the baud rate to 9600, turned the PPS on, and enabled
> >>> NEMA 3.x.
>
> >> The NMEA driver in ntpd is not expecting you to change the baud rate.
> >> There may be some way to configure it to use other baud rates, but I
> >> don't remember anything like that.
>
> >>> The other one I configured using cu. I turned off all of the output
> >>> sentences except for GPGG and turned the PPS on.
>
> >> The default setup for the NMEA driver is to use the GPRMC sentence.
> >> It can use a few others. Check the documentation or fix it to send
> >> (only) the GPRMC sentence.
>
> >> --
> >> These are my opinions, not necessarily my employer's. I hate spam.
>
> > The performance is still really bad:
> > remote refid st t when poll reach delay
> > offset jitter
> > ==============================================================================
> > x192.168.0.2 69.25.96.13 2 u 1 16 377 0.130
> > 4.307 0.417
> > 192.168.0.26 192.168.0.2 2 u 47 16 210 0.000 0.000
> > 130.357
> > 192.168.0.27 .STEP. 16 u - 16 0 0.000
> > 0.000 0.000
> > x192.168.0.29 .GPS. 1 u 11 16 376 0.086
> > -199.29 0.172
> > xGPS_NMEA(0) .GPS. 0 l 4 16 377 0.000
> > -220.73 2.039
>
> > remote refid st t when poll reach delay offset
> > jitter
> > ==============================================================================
> > 192.168.0.26 192.168.0.2 2 u 13 16 42 0.007
> > 15.204 0.409
> > 192.168.0.27 192.168.0.29 2 u 1214 16 0 0.001
> > 40.722 0.000
> > 192.168.0.28 71.80.83.0 3 u 2 16 377 0.018
> > 199.327 0.123
> > *GPS_NMEA(0) .GPS. 0 l 3 16 377 0.000
> > 0.605 3.320
>
> > _______________________________________________
> > questions mailing list
> > questi... at lists.ntp.org
> >https://lists.ntp.org/mailman/listinfo/questions
>
> --
>
> David R. Andersen
> Professor
> Department of Electrical and Computer Engineering
> Department of Physics and Astronomy
> The University of Iowa
> Iowa City, IA 52242
>
> Email: k... at uiowa.edu <mailto:k... at uiowa.edu>
> Tel: (319) 335-2529
> Fax: (319) 353-1115
> Web:http://dx.eng.uiowa.edu/dave/
The sym links are ok.
NTP doesn't seem to like 9600 baud with GPGGA. Reach is still zero.
remote refid st t when poll reach delay
offset jitter
==============================================================================
*192.168.0.29 .GPS. 1 u 2 16 376 0.085
-0.457 0.021
GPS_NMEA(0) .GPS. 0 l - 64 0 0.000
0.000 0.001
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