[time-nuts] Need Time Help

David J Taylor david-taylor at blueyonder.co.uk
Thu Oct 20 05:48:32 EDT 2016

From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Mark Sims

Lady Heather has support for setting the system clock from the GPS receiver. 
The next release has support for analyzing and compensating for the GPS / 
system / com port message delay.  It does not use the 1PPS signal.

It can get the Windoze clock to under 40 msecs (two times the typical 
Windoze 16 msec clock interval).   It can reset the system clock on command, 
periodically, or whenever the GPS time and system time diverge by more than 
x milliseconds.  However it does not have the finesse of NTP that guarantees 
on monotonically increasing system clock... it just "jam syncs" the clock to 
the GPS time.  I know there are people using it for EME work in the field 
where there is no net connection available for NTP, etc.


You may be able to do much better than 40 ms if you can use the recent 
GetSystemTimePreciseAsFileTime function.


What I do in my own software is to define a function named like: 
GetSystemTimePrecise  and code that so that when running on Win-8 and later 
it uses the new function and when on earlier Windows it uses the earlier 
GetSystemTimeAsFileTime.  NTP uses this function and it works extremely 

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Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
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