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

Uwe Klein uwe at klein-habertwedt.de
Fri Aug 26 07:41:02 UTC 2011

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.

Can you access the output strings via a debugger?
i.e. trace writes on the port for that process?

Much easier to get an idea what is actually sent.


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