[ntp:questions] Garmin GPS 18LVC Setup but questions on best way
George R.Kasica
georgek at netwrx1.com
Tue Dec 30 18:12:47 UTC 2008
On Tue, 30 Dec 2008 17:24:36 GMT, "David J Taylor"
<david-taylor at blueyonder.neither-this-part.nor-this-bit.co.uk> wrote:
>George R. Kasica wrote:
>[]
>> Next step....I added back GPS NEMA data without the gpsd daemon (I
>> don't pass the data out to anywhere so there's no real need for it)
>>
>> and I see
>>
>> # ntpq -p
>> remote refid st t when poll reach delay offset
>> jitter
>> ==============================================================================
>> xGPS_NMEA(0) .GPS. 0 l 13 16 377 0.000 -616.37
>> 10.466
>> *SHM(0) .PPS. 0 l 14 16 377 0.000 -0.557
>> 0.712
>> eagle-local 192.168.1.7 2 u 36 64 377 0.153 -44.398
>> 0.607
>> apollo-local 192.168.1.7 3 u 24 64 377 0.250 -16.713
>> 1.912
>> -mirror 209.132.176.4 2 u 29 64 377 10.272 6.391
>> 135.974
>> +tesla.fireduck. 198.82.1.202 3 u 28 64 377 36.123 2.841
>> 115.565
>> +rikku.vrillusio 209.51.161.238 2 u 21 64 377 38.531 -3.260
>> 156.267
>>
>>
>> I have good PPS and am getting GPS NEMA in as well but the offset for
>> the NEMA data seems quite large....what would I do to fix that??
>>
>> George
>
>George,
>
>On my FreeBSD system, the ntpq -p output looks like this (some servers
>omitted):
>
> remote refid st t when poll reach delay offset
>jitter
>==============================================================================
>-utserv.mcc.ac.u 193.62.22.98 2 u 58 64 377 25.548 3.732
>2.715
>*GPS_NMEA(1) .PPS. 0 l 52 64 377 0.000 0.002
>0.008
>
>With just the reference clock type 20, I get the accuracy needed. The PPS
>line from the GBS-18 LVC is wired to the DCD line of the serial port. In
>my ignorance, I don't see why you even need the SHM driver, but as I said
>before, I'm no expert! I don't see why my system picks up the PPS from
>just the type 20 driver, and yours does not.
>
Do you have the PPS kernel hack compiled in? That may be doing it for
you. I can't easily add that here with the Fedora Core 9 RPM kernel I
have. What are you using in your ntp.conf settings for the clock setup
lines and fudge?
George
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