[LinuxPPS] PC Clock Offset

[Andrew Hills]

> NTP does that for you so I am not sure why you wrote a utility to do this.  
> Just set the Oncore as your prefer peer and then you can query this with any 
> of the following:
> ...

I was writing a utility because I want to record these statistics to a 
file and plot the results. I've read that the peerstats file contains 
this information, but I'm struggling to find a source which will 
indicate exactly what each column of the file represents (including units).

> The above are examples from a well setup system with an Oncore UT+ ref clock.  
> Even though the above offset is only 79 nanoseconds the actual offset is 
> likely more since I have not tried to compensate for the latency of the PPS 
> interrupt handler which is probably on the order of several microseconds or 
> the delay in my serial cable which is probably around 9ns.

Can I assume the "DELAY 25.0 ns" line in my ntp.oncore.0 configuration 
file compensates for the cable delay? How could I go about measuring and 
compensating for the PPS interrupt handler latency?

--Andrew Hills