GPS Interface

[bryantee]

Having finaly got round to wiring up the Simrad TP 22 autopilot to the gps output for Nav to way point. At present a GPS Garmin 12 feeds the position into the DSC radio navman 7211> I have an Echo star 790 GPS and fish finder which displays depth, speed and feeds the Nasa repeater ( Does it well) in the cockpit.How do I intergrate all together.The radio refuses to reconise the 790 .The Garmin gps 12 will intergrate with radio and auto helm.If the GPS 12 is the way to go how do I split the signals? please

 

[Danny]

No-one seems to want to have a go so I'll give you my thoughts, for what they're worth...

The 790 is a fairly elderly piece of kit and has to be told whether to use NMEA 0180 or 0183 standard - so make sure it's set up for 0183! I'm fairly sure the Navman would turn its nose up at 0180. Not sure about the Nasa repeater - maybe it accepts both.

If you can't get the 790 output to drive the Navman then I'd recommend not spending too much time on it and just use the Garmin to drive everything - it will probably drive three 'listeners' with no problem. As far as connecting them goes: they're all wired in parallel. Brown wire on the Garmin data cable goes to the "NMEA data in", "data+" or "Signal in" terminals (different manufacturers choose different names to confuse us) on the repeater, radio and autopilot. The black wire (ground) on the Garmin cable goes to the "common", "data-", "ground" or whatever else the manufacturer has decided to call it.

I would connect from the GPS to the nearest "listener" first. Make sure it works. Then connect on to the next listener and make sure that both work, etc etc.

On the other hand, if you really want to use the 790 to drive everything then I'd do the following:
<ul type="square"> [*]Check that it's sending NMEA 0183 [*]Connect to the repeater and see if it works [*]Connect from the repeater to the radio and see if they both work [*]Connect from the radio to the a/p and check if all work [/list] If you get to the last step and the repeater is still working but one or both of the other two are not then you may have a problem with the sentences transmitted by the 790. This would require a PC or a protocol analyser of some sort to investigate further.