[ntp:questions] Fwd: Re: NetBSD GPS/PPS using 4.2.6p3

A C agcarver+ntp at acarver.net
Fri Aug 26 20:16:49 UTC 2011

On 8/26/2011 13:14, A C wrote:
> On 8/26/2011 02:30, David Lord wrote:
>> A C wrote:
>>>> I will try to capture the outgoing serial data sometime either this
>>>> weekend or the next when I have a bit more time. I'll send it along to
>>>> the list as soon as I do. For now I'll leave things using PPS only and
>>>> see how it works. But I still want to eventually get the GPS refclock
>>>> working along with PPS just to have a backup clock for network outages.
>>> Ok, so I've spliced up a serial tap cable to snoop on the data heading
>>> out towards the GPS. Unfortunately I can't seem to decode it. No
>>> amount of changing baud rates, stop bits and parity seems to show me
>>> anything but a stream of unreadable binary data.
>>> It seems to be coming out at 4800 baud although stty says the output
>>> speed of the port is 9600. The data seems to have a regular pattern to
>>> it with a few of the bytes changing.
>>> If anyone can think of a utility that will attempt to autosync to the
>>> data I'm open to suggestions. Otherwise I can try to capture the raw
>>> data if anyone wants to look at it. Either way, it only transmits
>>> while ntpd is using the port. If ntpd is shut down the data stops.
>> From type 20 driver reference:
>> Generic NMEA driver sends a $PMOTG,RMC,0000*ID<cr><lf>
>> command each poll interval?
> Except I'm not using the Type 20 NMEA driver. I only have the 22
> PPS_ATOM driver enabled.

Let me add that I'm using only the PPS_ATOM right now (GPS_NMEA is not 
in the ntp.conf file at all) and the 64-ish bytes of binary data is 
showing up at the serial port once per second.

However, even with a debug level of 10 I don't show anything being 
written to the port.

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