Last year another forumite posted a project for a nmea multiplexer, i am now in the position where i need one.
I am unable to find the post relating to this so i am asking if anyone else happed to save the details.
I have investigated Brookhouse, and their range is very adaptable to different layouts - but they are not answering their e-mail on the website. I was asking who the UK agent is?
They are a lot cheaper than the Raymarine equiv.
do you mean a multiplexer or expander?
A multiplexer takes many NMEA data streams in and puts them all together on a single data stream - v. complicated and not really DIYable unless you can do wonders with microcontrollers and embedded software. An expander takes a single NMEA data stream in and rebroadcasts it on multiple outputs, so that a GPS for example can talk to loads of different 'listeners'
I did a DIY expander last year - the ciruit diagram is around somewhere if you need it.
you could try these people for multiplexers http://www.shipmodul.com/en/index.html
I've thought a lot about this - the complexity is in knowing which occurrences of which sentences to drop in order to fit your quart into a pint pot.
For any given application this is comparatively easy - to do it in the general case is much more complex, and would require fairly powerful computation in the multiplexer that would significantly increase the hardware complexity and cost.
NMEA is strictly one talker per circuit - any more than that then you are very lucky if it works at all.
In my present set up I have a switch to select whether the autohelm receives wind data or gps data, but not both. I can't see that it is useful to feed the fishfinder data into the autohelm, so that can be ruled out.
If your laptop is a central part of the system then you could use that as the multiplexer - which would make the task a good deal simpler.
Me too .. easy to install, worked first time. Pretty good price too, though perhaps not the cheapest certainly far from the most expensive. They have a range of connectivity options for connection to a PC (ie blue tooth etc)