[ntp:questions] best gps receiver for time synchronization

Unruh unruh-spam at physics.ubc.ca
Tue Mar 10 17:29:22 UTC 2009

jack <j.jack.wang at gmail.com> writes:

>Hi everyone,

>First of all, I thank you for all your response.

>I understand the best solution would be using an IRIG board and that's
>what we had been using. We are now trying to make our product more
>compact by using a small single board PC with no RS 232 or PCI slot
>(no slot at all). Currently I am using GPS antenna with a USB

>I also understand that if I can get a small PC with one genuine RS232,
>I can use Dave Hart's solution as tested by David. I will try to my
>best to steer the project towards this direction.

>Right now, I am trying to find the best GPS antenna that outputs at a
>consistent pace (better if the output can be configured so I only
>receive time stamps). Any recommendations wrt that?

Not at all sure what you mean. IF you do not use the PPS output, you will
never get timing better than a few ms. Not at all sure what :consistant
pace" means. 
And from what I have read, USB itself has its own variability. Ie, you
cannot get consistant output from a USB port, no matter what receiver you
use. It is like giving your secretary a highly accurate deskclock, and then
getting the time by telling her to read it and walk over to your office  on
another floor to tell you the time. 

>Thanks again.


>On Mar 10, 4:59=A0am, Martin Burnicki <martin.burni... at meinberg.de>
>> Jack,
>> jack wrote:
>> > Hi all,
>> > I am trying to sync my Windows box to an external GPS source. I
>> > currently have BU353, whose output is not very periodic. I read up on
>> > ntpd implementation that uses PPS signal but I don't even have an RS
>> > 232 port on my computer.
>> > My questions:
>> > 1) what's the best GPS antenna (and protocol) in terms of
>> > consistencies in its output?
>> > 2) what kind of accuracy can i expect?
>> This is somewhat limited under Windows due to the granularity of the Wind=
>> system clock.
>> Alternatively you could install a GPS PCI card which your applications ca=
>> also access directly, so you can benefit from the full accuracy of the
>> card, e.g.:http://www.meinberg.de/english/products/gps170pex.htm
>> Take care, though, I'm biased! =A0;-))
>> Martin
>> --
>> Martin Burnicki
>> Meinberg Funkuhren
>> Bad Pyrmont
>> Germany

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