I think the point is that the ship already has a very good GPS system
for navigation.  There is no need to buy another GPS for the clocks.
However considering the age of the clock system, I wonder if the GPS may
also be anchient (for a GPS).  I would ask what model of GPS they have
and see if it has a NMEA output.  Also the NMEA output may already be
used by something else so you may have to live with whatever data format
and update rate they are currently using.

Considering that these clocks are not used for navigation, I think a
standard uP Xtal should keep time well enough for brief interruptions
like going under a bridge or even a few hours.  Try something like:

1)      Process NMEA string in buffer
2)      generate anticipated NMEA string in buffer
3)      If real string arrives overwrite generated string
4)      wait until next NMEA string should have arrived, based on uP Xtal
5)      goto 1

Sherpa Doug

> -----Original Message-----
> From: Roman Black [mailto:fastvid@EZY.NET.AU]
> Sent: Wednesday, January 23, 2002 8:46 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: Replace old chips ?
>
>
> Bob Ammerman wrote:
> >
> > GPS units will provide you with NMEA strings that contain
> the current time.
> > You can just use that time as long as the GPS is receiving.
>
>
> Aren't most GPS modules fussy about antenna
> line of sight? I've heard a lot about problems
> with loss of signal going under bridges etc.
> Surely in a steel ship it's going to need an
> external antenna?
> -Roman
>
> --
> http://www.piclist.com hint: The list server can filter out subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics
>
>
>

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics