[ntp:questions] PPS problem

David Lord snews at lordynet.org
Wed Apr 2 20:25:18 UTC 2014


David Lord wrote:

.....


> I currently use a "Sure" gps, ntp-dev-4.2.7p433 on NetBSD-6
> 
> I have a few significant differences in my ntp.conf
> 
> #################
> tos orphan 10

A few more comments

tos orphan 10 # is to replace your three lines:
server 127.127.1.0 #lo server
fudge 127.127.1.0 stratum 7
restrict 127.127.1.0 noquery nomodify notrap

> tos mindist 0.4  # allows pps to kick in
>     ^^^^^^^^^^^

> server 127.127.20.2 mode 18

You can use this as prefer peer:
server 127.127.20.0 prefer

> fudge  127.127.20.2 stratum 7 time2 0.407 flag1 0 refid GPSb

Required value for time2 will depend on your GPS model and
firmware version.

> server 127.127.22.2 minpoll 4 maxpoll 4
> server 127.127.22.2 flag2 0 flag3 1 refid PPSb
> server -4 <ntp0.mydomain>
> server -4 <ntp1.myisp> minpoll 8 maxpoll 10 iburst prefer


For what it's worth the last entry in my
/var/log/ntp-stat.20140402:

Wed Apr  2 17:36:00 GMT 2014
      remote   refid st t poll reach   delay   offset  jitter
============================================================
-GPS_NMEA(2) .GPSb.  7 l   64  377    0.000   -1.940   8.828
oPPS(2)      .PPSb.  0 l   16  377    0.000    0.000   0.004
+ns0.lordyne 81.187  3 u   64  377    1.363   -0.175   0.202
  ns2.lordyne 192.16  2 u   64  377    0.498   -0.237   0.613
+ns1.lordyne 81.187  3 u   64  377    0.577    0.007   0.703
+ns3.lordyne 81.187  3 u   64  377    0.849   -0.486   0.690
*ntp1.xxxxxx 195.66  2 u  256  377   19.589   -0.943   0.403

associd=0 status=011d leap_none, sync_pps, 1 event, kern,
pll offset:            -0.000317
pll frequency:         -35.8115
maximum error:         0.406
estimated error:       3e-06
kernel status:         pll ppsfreq ppstime ppssignal nano
pll time constant:     4
precision:             1e-06
frequency tolerance:   495.911
pps frequency:         -35.8115
pps stability:         0.00480652
pps jitter:            0.002
calibration interval   256
calibration cycles:    6087
jitter exceeded:       7635
stability exceeded:    0
calibration errors:    20

ntp_adjtime() returns code 0 (OK)
   modes 0x0 (),
   offset -0.317 us, frequency -35.812 ppm, interval 256 s,
   maximum error 406000 us, estimated error 3 us,
   status 0x2107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL,NANO),
   time constant 4, precision 0.001 us, tolerance 496 ppm,
   pps frequency -35.812 ppm, stability 0.005 ppm,
   jitter 1.500 us, intervals 6087, jitter exceeded 7635,
   stability exceeded 0, errors 20.


David



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