[ntp:questions] Re: Bought a GPS receiver--What next?

David Schwartz davids at webmaster.com
Tue Nov 2 02:16:49 UTC 2004


"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message 
news:hISdnS39t4qMdxvcRVn-pQ at comcast.com...

> We had a long discussion on the topic here a few weeks ago.  The long
> and the short of it is that Motorola should have written a much better
> manual.  The chapter on how it all works leaves far too much room to
> read between the lines.  The leading edge of the PPS signal marks the
> exact "top of the second".  The receiver adjusts its measurement epoch
> to keep it within one millisecond of the top of the second..  There are
> facilities built into the Motorola command set to allow adjusting the
> "top of the second" for cable delays and other systematic errors.

    One millisecond is pretty poor PPS accuracy for a GPS receiver intended 
for timing applications. One microsecond is typical.

    DS





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