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?

Agreed, not trivial. But maybe fun anyway!



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:


based on:


and just messing around!  Perhaps it's of interest or use?

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