David, I got this going and everything is working well. However, comparing NTP time to an IRIG board time with a GPS antenna, I see a difference of 100ms. Not sure where this came from.
Jack On Dec 2, 2:29 am, "David J Taylor" <david-tay...@blueyonder.not-this- bit.nor-this-part.co.uk.invalid> wrote: > > David, > > > I looked at timeGetTime() and I found it only gives out relative time > > (since Windows was started). Is it possible to query NTP server to get > > an accurate starting time? > > > jack > > As Dave Hart says, you would need to do a network transfer to get the time > from NTP - that's a bit of a pain when it's running locally. A pity that > Dave's new DLL couldn't include a very simple get current time call! Hint > Dave! Call: GetNTPTime - returns a 64-bit value. However, a network > query should take less than a millisecond on the local PC, so you could > then use the timeGetTime function. The ambiguity is around 49 days, so it > shouldn't be an issue. The other much more accurate way /may/ be to use > QueryPerformanceCounter - a 64 bit counter running at either a few MHz or > even at CPU-speed. Yes, it would need calibrating, and you may also have > to deal with CPUs where the speed changes (also an issue for NTP), and > there may also be an ambiguity issue. > > If you go the SNTP route, the packet you need is easy to construct, and > it's on page 7 here: > > http://www.ietf.org/rfc/rfc2030.txt > > It's what my Delphi SNTP monitor program uses, and has about a dozen > fields to complete. > > http://www.satsignal.eu/software/net.htm#NTPmonitor > > 73, > David _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
