[ntp:questions] PPS problem

Simchaev Arthur-BAS071 BAS071 at motorolasolutions.com
Thu Apr 3 07:51:16 UTC 2014


Hi Guys 
Thank you to your assistance . Seems is working now .
I see that NMEA chosen as PPS peer server :

remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
oGPS_NMEA(0)     .GPS.            0 l   12   16  377    0.010   -0.030   0.031. 

But please clarify the following :
1) Can I sure that is update the system clock in PPS resolution
2) Why I still doesn't see PPSFREQ,PPSTIME,PPSSIGNAL , when I run ntptime .
My output is following :
ntptime
ntp_gettime() returns code 0 (OK)
  time d6e78fed.18c23fa0  Thu, Apr  3 2014  7:44:45.096, (.096714581),
  maximum error 3888 us, estimated error 474 us, TAI offset 0
ntp_adjtime() returns code 0 (OK)
  modes 0x0 (),
  offset 50.880 us, frequency -26.830 ppm, interval 1 s,
  maximum error 3888 us, estimated error 474 us,
  status 0x2001 (PLL,NANO),
  time constant 4, precision 0.001 us, tolerance 500 ppm. 

root at am335x-evm:/var/lib/ntp# ntpq -c as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
  1 65397  976a   yes   yes  none  pps.peer    sys_peer  6
root at am335x-evm:/var/lib/ntp# ntpq -c "rv 65397"
associd=65397 status=976a conf, reach, sel_pps.peer, 6 events, sys_peer,
srcadr=GPS_NMEA(0), srcport=123, dstadr=127.0.0.1, dstport=123, leap=00,
stratum=0, precision=-20, rootdelay=0.000, rootdisp=0.000, refid=GPS,
reftime=d6e79065.fffb1778  Thu, Apr  3 2014  7:46:45.999,
rec=d6e79066.73ee526e  Thu, Apr  3 2014  7:46:46.452, reach=377,
unreach=0, hmode=3, pmode=4, hpoll=4, ppoll=4, headway=0, flash=00 ok,
keyid=0, offset=0.054, delay=0.000, dispersion=0.262, jitter=0.031,
filtdelay=     0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00,
filtoffset=    0.05    0.06    0.06    0.06    0.07    0.06    0.07    0.05,
filtdisp=      0.03    0.27    0.51    0.75    0.99    1.23    1.47    1.71

3) Since I can attach only one GPS to the board ntp.conf is following :

tos orphan 6 
driftfile /var/lib/ntp/ntp.drift 
 

server 127.127.20.0 minpoll 4  iburst #NMEA Server
fudge   127.127.20.0 flag1 1 flag2 0 time2 0.500

Regards
Arthur
 

-----Original Message-----
From: questions-bounces+bas071=motorolasolutions.com at lists.ntp.org [mailto:questions-bounces+bas071=motorolasolutions.com at lists.ntp.org] On Behalf Of David Lord
Sent: Wednesday, April 02, 2014 11:25 PM
To: questions at lists.ntp.org
Subject: Re: [ntp:questions] PPS problem


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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