[ntp:questions] Garmin GPS 18LVC Setup but questions on best way

Unruh unruh-spam at physics.ubc.ca
Mon Dec 29 23:47:56 UTC 2008


George R. Kasica <georgek at netwrx1.com> writes:

>>>Since you have a GPS receiver, three internet servers should be 
>>>sufficient as backup and a sanity check for the GPS.
>>See below, now set up as recommended with three us.pool.ntp.org
>>servers but as you say it will take some time to be useful, but I
>>don't seem to be getting the NEMA data as of 1415Z 28-dec-2008.
>>
>># ntpq -p
>>     remote           refid      st t when poll reach   delay   offset
>>jitter
>>==============================================================================
>> GPS_NMEA(0)     .GPS.            0 l  273   16    0    0.000  -664.93
>>0.002
>>xSHM(0)          .PPS.            0 l    7   16  227    0.000  -634.51
>>349.893
>> eagle-local     192.168.1.7      4 u   11   64   37    0.120  -11.083
>>0.523
>> apollo-local    192.168.1.7      3 u   18   64   37    0.224    6.685
>>0.765
>>x64.247.17.251   129.6.15.28      2 u   12   64   37   34.158  -18.850
>>6.764
>>+ip-72-167-54-20 204.123.2.72     2 u   13   64   37   82.722    1.031
>>1.821
>>*caspak.cerias.p .GPS.            1 u   10   64   37   22.867    7.745
>>10.934
>>

>OK here is about 21 hours later 11Z 29 Dec-2008:

># ntpq -p
>     remote           refid      st t when poll reach   delay   offset
>jitter
>==============================================================================
>xGPS_NMEA(0)     .GPS.            0 l    2   16  375    0.000  -722.08
>9.115
>xSHM(0)          .PPS.            0 l    6   16  377    0.000  -722.20
>7.892
> eagle-local     192.168.1.7      4 u  390 1024  377    0.181   -5.629
>4.389
> apollo-local    192.168.1.7      4 u  410 1024  377    0.311   -2.394
>0.299
>*got.my.mojo.net 192.5.41.41      2 u  966 1024  377   30.157   -5.166
>0.361
>+kiri.nonexiste. 64.202.112.75    2 u  644 1024  377    9.423   -5.517
>203.143
>+host2.kingrst.c 99.150.184.201   2 u  944 1024  377   16.221  -11.608
>16.695


>still seing both of the local GPS/PPS entries as false tickers but I
>also see the offsets are huge compared to other clocks...where do I go
>from here to correct this??

OK, it is really really suspicious that both nmea and shm are equal amounts
off. That should not be. It is as if your shm is actually reporting the
nmea time rathr than the pps time. 

What are you running to deliver the shm signals to the system?



>ntp.conf is below:

># LinuxPPS: GPS 
>server 127.127.20.0 minpoll 4 
>fudge 127.127.20.0 flag3 1 flag2 0
> 
># SHM: PPS filtered mean 
>server 127.127.28.0 minpoll 4 
>fudge 127.127.28.0 refid PPS flag3 1
> 
>server eagle.netwrx1.com iburst
>server apollo.netwrx1.com iburst
>server 0.us.pool.ntp.org iburst
>server 1.us.pool.ntp.org iburst
>server 2.us.pool.ntp.org iburst




More information about the questions mailing list