[time-nuts] PC time app

Chris Albertson albertson.chris at gmail.com
Sat Nov 26 05:50:58 UTC 2011


On Fri, Nov 25, 2011 at 9:24 PM, David J Taylor
<david-taylor at blueyonder.co.uk> wrote:
>> Dunno.  Does the NMEA driver work on the Meinberg NTP for Windows?
>
> Yes, although from some GPS devices the jitter may be worse than from
> Internet servers (depending on your connection).  Given that NTP is free,
> works extremely well, is well documented, and can be monitored and managed
> remotely, I don't see why you would want to pay for program which doesn't
> work as well.
>

That is what every Linux user says about Windows.

But it's worse than just not working as well "jumping the clock" is a
defective design.  Any software that periodically sets the clock will
break a lot of other software that tries to measure time intervals.
It is simple:  The way to meaue a time interval is to sample the
clock, do something, then sample the clock gain.  then subtract the
first time from the last and then you know how long it took to do that
something.    Setting the clock periodically breaks this.   The only
thing that can work is to adjust the clock RATE by tiny amounts

Now if you only need enough accuracy so that you are not late to
appointments then just do "whatever".  But we assume on a time nuts
list that we care about milli and micro seconds at least

Chris Albertson
Redondo Beach, California



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