[ntp:questions] best gps receiver for time synchronization

jack j.jack.wang at gmail.com
Tue Mar 10 18:56:56 UTC 2009


David,

Thanks again for your suggestion. It seems Garmin 18X USB can be
tailored to only output certain messages as you said. Hopefully this
will improve the performance. I am going to give it a try.

To all others:
I am only trying to find the best solution given my other constraints.
Will try in the future to go with a system that can take advantage of
the 1PPS signal.

jack

On Mar 10, 2:18 pm, "David J Taylor" <david-tay... at blueyonder.neither-
this-bit.nor-this.co.uk> wrote:
> Unruh wrote:
>
> []
>
> >> The newer "x" version appears to be a lot more sensitive, at the
> >> expense of somewhat higher current consumption.  You can tell the
> >> LVC version what sentences to send.  Better check the technical spec
> >> to see what the USB one can be told to do:
> >>  http://www.garmin.com/manuals/GPS18x_TechnicalSpecifications.pdf
>
> > Unfortnately, the LVC is a serial port output, plus a PPS output. The
> > USB
> > version has no PPS output and is liable to have pretty bad timing
> > (where good=usec).
>
> .. which is why I suggested checking in the manual as to whether the
> output could be set to be a better determined length, which is what the OP
> requested.  It may be he /has/ to use USB.
>
> By the way, while timing on USB may not be wonderful, I have an
> application receiving some 40GB per day over USB, in fairly small packets
> from a DVB satellite feed, and the buffering isn't that great (a few
> kilobytes, I believe).  Most often it's lossless, but it may be that the
> error-correction in the stream-to-file software does a good job!  <G>
>
> Cheers,
> David




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