[ntp:questions] help with setting up NTP on windows with a USB GPS

Unruh unruh-spam at physics.ubc.ca
Sat Nov 28 00:24:42 UTC 2009


"David J Taylor" <david-taylor at blueyonder.not-this-bit.nor-this-part.co.uk.invalid> writes:

>"David Woolley" <david at ex.djwhome.demon.invalid> wrote in message 
>news:hen3cv$nit$1 at news.eternal-september.org...
>> jack wrote:
>>>
>>> I am trying to setup NTP on Windows XP with a USB GPS at "COM1". I can
>>
>> You are making life difficult.  Without PPS, GPS has poor accuracy, and 
>> potentially high jitter.  USB adds a lot of extra jitter.  Windows is 
>> not the best platform for time keeping.
>>
>>>
>>> I installed the Meinberg NTP server and then overwrote ntpd.exe with
>>
>> Meinberg don't do an NTP server, they do a Windows installer for the 
>> reference version of ntpd.

>So in these days of energy economy would your solution be to install 

So throw away all your computers. Then all of these problems disappear. 

>another PC running a different OS (with all the associated extra learning) 
>just so that accuracy could be improved from scores of microseconds to 

I think you mean 10s of msec to 1s of microseconds. If you do not need
it, certainly using a separate computer would be overkill. If you need
it, then presumably you have to factor in the costs and figure out how
much you need it. 
I would certainly NOT use USB for accuracy. I would certainly not use
Windows for accuracy. 
On a windows system, using the net (Ie external servers ) might well be
just as good or better than a usb gps. 


>microseconds?  Does jack need the greater accuracy?  Using USB doesn't 
>mean you need to give up PPS - some serial-to-USB converters carry the DCD 
>line.  Even with USB, even with Windows, fractions of milliseconds are 
>achieved as I show on my Web page.

>Whilst I see what you mean, pedantically, Meinberg's installation of 
>ntpd.exe works just like any other NTP server, by the way.

>Cheers,
>David 




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