Radio Ocean AIS/VHF to Raymarine C120 Classic

[robmcg]

trying to get my C120 plotter to talk to the Radio Ocean combined AIS and VHF - but without much luck! The plotter will happily accept the AIS data from the radio but the radio resolutely refuses to accept a GPS input via NMEA 0183 from the plotter. I know the plotter is outputting this data as the NASA VHF I have removed derived its position data from the plotter but so far nada! Nowt! Not a sniff of a position! Anyone connected these two pieces of kit together or could suggest any common instal errors? Anything appreciated!

Rob

 

[prv]

How many NMEA ports does the C120 have? If there's only one, and it does input and output at the same speed, then you may be stuffed. AIS data comes in at 38400 baud, whereas position data is generally at 9600.

What speeds do you have set?

Pete

 

[maby]

Looks to me that the input and output sides of each port have to run at the same speed, so that is probably your problem. The C120w has two bidirectional NMEA0183 ports plus an input only port that only runs at 4800bd. You certainly need to connect the AIS output of the radio to the NMEA0183 Port 2 input of the plotter since that is the only input able to run at 38k. Unless you can configure the radio to accept positioning data at 38k, you'll need to connect the port 1 output of the plotter to the GPS input of the radio. Go into the settings menu on the plotter/system integration and set port 1 to 4800bd and port 2 to 38kbd.

 

[robmcg]

How many NMEA ports does the C120 have? If there's only one, and it does input and output at the same speed, then you may be stuffed. AIS data comes in at 38400 baud, whereas position data is generally at 9600.

What speeds do you have set?

Pete

Thanks Pete. It has got me thinking, the Radio Ocean has a built in multiplexer but I may well have set the NMEA baud rate on the plotter to 38400 - which would suggest it wouldn't output the GPS position at that speed. I will try to reset the port to 4800 which should allow the VHF to accept the GPS data and multiplex it with the AIS data - or at least that's what the unhelpful Radio Ocean VHF manual says!

Rob

 

[maby]

You cannot feed in AIS data at 4800bd - it's far too slow. Most AIS receivers don't even have the option of reducing the data rate and, even if they did, you would lose vast amounts of data at 4800bd in any busy area.

 

[David2452]

Trouble with the C120 classic is if you switch to high speed 0183 for AIS in it also switches the output to high speed, most VHFs will not accept that. You can not vay the speeds for talk and listen its either one or the other.

 

[robmcg]

You cannot feed in AIS data at 4800bd - it's far too slow. Most AIS receivers don't even have the option of reducing the data rate and, even if they did, you would lose vast amounts of data at 4800bd in any busy area.

This one does! Although it does say that some data may be lost at this rate. The whole idea of the combined VHF AIS was that it would take the NMEA GPS signal and redirect it back to the plotter with the AIS data via its own multiplexer. I am guessing this doesn't really work in practice so is a pretty useless feature - albeit the feature that made me buy it in the first place

 

[pvb]

This one does! Although it does say that some data may be lost at this rate. The whole idea of the combined VHF AIS was that it would take the NMEA GPS signal and redirect it back to the plotter with the AIS data via its own multiplexer. I am guessing this doesn't really work in practice so is a pretty useless feature - albeit the feature that made me buy it in the first place

I think you're getting confused here. The radio will take a GPS input from a separate GPS receiver and multiplex it and output to the plotter with the AIS data. It won't take GPS data from the plotter and send it back to the plotter. Where does your plotter get its GPS data from?

 

[prv]

I think you're getting confused here.

+1 - why would you want to take GPS data from the plotter, loop it through the radio, and send it back into the plotter? That's what you seem to be saying, but it makes no sense.

In fact, doesn't the C120 lack a GPS receiver anyway? I know my C70 does, it needs an external GPS to feed it over either NMEA or Seatalk. So are you trying to connect some external GPS and loop it via the radio into the plotter? That would make sense, but only requires one connection from radio to plotter.

Pete