[ntp:questions] Driver Help?

Karl Denninger karl at denninger.net
Tue Jun 12 23:59:05 UTC 2007


Richard B. Gilbert wrote:
> Karl Denninger wrote:
>> I'm hacking a copy of the NMEA driver to work with the CDMA modems 
>> (which provide a clock signal even if not subscribed - kinda 
>> interesting) and have it talking to the device.
>>
>> But - even though the dispersion looks reasonable and so does jitter, 
>> the application refuses to consider it "synced".
>>
>> I have the following.....
>>
>> ntpdc> sysi
>> system peer:          CDMA(0)
>> system peer mode:     client
>> leap indicator:       11
>> stratum:              16
>> precision:            -19
>> root distance:        0.00000 s
>> root dispersion:      0.00165 s
>> reference ID:         [67.68.77.0]
>> reference time:       00000000.00000000  Thu, Feb  7 2036  0:28:16.000
>> system flags:         auth monitor ntp kernel stats
>> jitter:               0.001129 s
>> stability:            0.000 ppm
>> broadcastdelay:       0.003998 s
>> authdelay:            0.000000 s
>> ntpdc> peer
>>     remote           local      st poll reach  delay   offset    disp
>> =======================================================================
>> *CDMA(0)         127.0.0.1        0   16  377 0.00000  0.241065 0.00697
>> ntpdc>
>>
>> Obviously, I'm missing SOMETHING....... the dispersion looks 
>> reasonable, but it will not lock up on the clock.  Any idea where I 
>> start?
> 
> I think you may be missing the "*" in column one above.  That indicates 
> that ntpd has your CDMA(0) clock as the synchronization source.
> 
> The offset looks a little high unless ntdp was started quite recently. 
> Bear in mind that ntpd needs time to beat your clock into submission. 
> Thirty minutes is a good length of time to wait before taking offset and 
> dispersion figures seriously.
> 

Ok... I'll wait a good long while (several hours)

This thing isn't the BEST time source ever invented, but I've got a few 
folks who would like it as a solution, and of course I'll contribute the 
driver back to the codebase - if I can get it to work!

The other problem - that the driver's "start" routine is never called 
unless ntpd is not running as a daemon - is puzzling.  Not quite sure 
why that would happen.... but the routine is definitely not being 
entered, although the base code IS running (the startup message gets 
logged to the syslog and there are no errors.)

Its almost like the config file switch is ignored if its not in debug 
mode and thus didn't attempt to start the clock.  I can get a sysi but a 
peer shows no data (as expected with no clocks or peers attached)

I built this from source of the current RC2 source - I'm a long-time 
NTPD user (and have a Stratum 1 server running here with a GPS+PPS 
source), but haven't (yet) attempted to integrate a "new" clock into the 
codebase.

-- 
Karl Denninger (karl at denninger.net)
http://www.denninger.net




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