Raymarine C+AIS

[gjgm]

I m returning to this, as I guess the C series is pretty popular and adding AIS might be a popular step.
I used the Comar AIS Multi, which has an internal aeriel splitter. Its dead simple. Unconnect the VHF aeriel from the radio,connect into the AIS unit, and connect the AIS antenna cable back into the radio, connect the NMEA cable, and some power. Set the C series NMEA speed to AIS, and there you go.
Well, for the AIS anyway.
Problem now is that you dont have any GPS signal to the VHF. NMEA, as I understand it, cant send and receive.. so, as its is receiving the AIS data, it cant be used to send the GPS data to the radio. The GPS is connected by Raymarine's Seatalk, which isnt compatible with the radio. So, the simple solution is to buy the Raymarine interface unit, which costs not far off what the AIS unit itself costs, which is a big GGRRRR.
So some questions...
Is there anyway to wire this up?
Is there an alternative,cheaper,interface unit than the Raymarine?
Can I just add an extra gps antenna.. are they generic?That looks like half the cost.
A brand new Raymarine radio is the same price as the interface unit. Will a new radio accept Seatalk?
How about a handhelp GPS with an NMEA out?
The AIS unit seems some clever stuff for the money, but its somewhat frustrating if its going to cost almost the same again just to get the radio functioning as it was.

 

[alan17]

I have gone down the route of 2 GPS units. One Raymarine outputting seatalk the other, a Garmin< to serve the DSC and the yeoman plotter.

The further advantage of this route is the extra safety of 2 positioning devices plus dead reckong and EP.

Belt and braces but safe.

 

[Hurricane]

I'm sure I'm going to get shot down here but NMEA is only a 5v version of RS232.
In the past, I've just joines two RS232 receivers together - fed from one transmitter. Make sure that all the Rx and TX have the same levels (in other words 5v NMEA).

So, a really cheap way would be to simply join the NMEA output from the GPS to the new Comar's input and the C Series input.
I'm sure someone will say why this isnt a good idea or wont work but.....

A more correct method would be to use (as has been said on here a number of times) a NMEA multiplexer which is what (I think) the Raymarine device is. There are cheaper ones - have a look at JG Electronics - I'm sure he will have something thats cheaper than Raymarine.

I stand back and wait for the flack!!! /forums/images/graemlins/laugh.gif

 

[MarieK]

This confuses me also but here is my understanding...

It is not that NMEA cannot send and receive at the same time it is the fact that you have changed the speed of the BUS so the radio stops working as it cant read at that speed. On my Easy AIS unit there was a jumper to change the speed to 4800 baud, this meant radio and ais worked together.

What I dont know is if the AIS is as efficient at this lower baud rate.

How many NMEA ports does the c120 have? If more than one you have the radio and ais on different ports.

Ryan

 

[gjgm]

So, a really cheap way would be to simply join the NMEA output from the GPS to the new Comar's input and the C Series input
***
I had a look at the present cabling. The output from the Raymarine gps pod has 3 cables, which are joined onto the Tridata, and the Seatalk cable. I had wondered if the gps antenna cant feed both Seatalk, and the radio.. but if I tried that, the gps signal was lost, so that didnt seemed to work.
Looks like the Raymarine unit can be found for about £120, which is somewhat better. Thats probably an easier solution that another gps or antenna, but its not adding much value !
Anway. not Comar's fault at all, but I didnt realise that AIS wasnt quite so plug and play as I had thought (well, the Raymarine unit is!) So, I guess I m advising people with C series, that if you add in AIS, your radio dsc wont work, as is...

 

[Hurricane]

Not actually sure what you are doing but is one of these any use?
http://www.jgtech.com/pdf/miniplex-lite.pdf

3 NMEA "listenning" ports and the "talker" port can drive up to 4 devices (this is what I was saying about just joining it up). It also converts baud rates so the 38.4K output from the AIS can be sent at a slower rate to the plotter if required. The other thing this device does is isolates the grounds so that you dont get any nasty earth loops that could screw up your galvanic protection.


£89 inc VAT from JG

The added value here is that you get a PC integrated as part of the deal - and you probably know that I'm a great believer of PC integration.
It should be possible to feed the output of the PC into the plotter and keep all your favourite waypoints/routes on the PC - uploading as required. This is, fundamentally, what I do with the G Series.

 

[gjgm]

thanks for taking the time,Mike.
I see these guys also do the Raymarine rs232 interface box At least that way it should damn well work! I think NickH said that was what was used on his set up, so even a bozo like me might be able to connect it up with setting fire to the boat /forums/images/graemlins/tongue.gif
As a by the by, I played about with the AIS yesterday.Two boats in the marina within 75ft of me kept setting of the alarm, as being under power, even though they clearly we not. All very well to have the transmit version too, but maybe if this system becomes more widespread, it needs a bit more discipline from leisure users.

 

[Hurricane]

[ QUOTE ]
Two boats in the marina within 75ft of me kept setting of the alarm

[/ QUOTE ]
Join the club /forums/images/graemlins/laugh.gif

It does get a little better once you get to sea though.

 

[gjgm]

just for others who find themselves in this situation,from raymarine:
Question
When I configure the NMEA port of my C/E-Series Multifunction Display for “AIS 38400” the devices connected to the NMEA output port cease receiving data.


Answer
The NMEA ports of the C/E-Series Multifunction Displays are not designed to simultaneously support 38400 BAUD AIS and 4800 BAUD NMEA 0183 protocols. Should you need to provide data to 4800 BAUD NMEA devices, it is recommended that Raymarine’s E85001 SeaTalk/PC/NMEA Interface Module be installed to bridge SeaTalk GPS, instrument, and navigational data for this equipment.

Well, now I know /forums/images/graemlins/tongue.gif