[time-nuts] PC time app

David J Taylor david-taylor at blueyonder.co.uk
Sat Nov 26 01:17:28 EST 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.

<G> - but if Linux doesn't run the software you need to run .....

> 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

.. and just to be clear, NTP does its best to use RATE adjustments, and 
avoid stepping the clock (except when the system is first booted).  It's 
other software which may step rather than rate adjust.

Cheers,
David
-- 
SatSignal software - quality software written to your requirements
Web:  http://www.satsignal.eu
Email:  david-taylor at blueyonder.co.uk 





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