> On Apr 10, 2018, at 12:23 PM, David J Taylor via time-nuts > <firstname.lastname@example.org> wrote: > > Hi, > > Yes, but isn't generating pulses OUT of a PC with low latency/jitter one > of the difficult issues? > > If we (somebody smarter than me...) flip this around and modify a copy > NTP to grab the QueryPerformanceCounter value when it gets a PPS pulse > and log that count, don't we now have a way to compare the high > resolution uncorrected counter to NTP and the external PPS? We would still be relying on NTP to report on it’s self. I can feed the PC a PPS from my GPSDO and let it report on that. Tell it to simply monitor the input, but not use it for disciplining. I get information, but it’s what NTP “thinks of it’s self”. Ideally one would like to get an output that can be independently measured. Bob > > Agreed, not trivial. But maybe fun anyway! > > Dan > ================================ > > Dan, > > Take a look at Dave Hart's patches to the Microsoft serial port driver, that > does something similar. The source may be in the NTP distribution, or > Meinberg may have a copy. At one time using the QueryPerfomanceCounter call > was an option (look for "QPC"). With Windows-8 and later there is a much > more precise GetSystemTime call which NTP uses. > > I played a little with those calls (in a non-serious way) and wrote some code: > > http://www.satsignal.eu/ntp/TSCtime.html > > based on: > > http://www.lochan.org/2005/keith-cl/useful/win32time.html > > and just messing around! Perhaps it's of interest or use? > > Cheers, > David > -- > SatSignal Software - Quality software written to your requirements > Web: http://www.satsignal.eu > Email: david-tay...@blueyonder.co.uk > Twitter: @gm8arv > _______________________________________________ > time-nuts mailing list -- email@example.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- firstname.lastname@example.org To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.