AIS link up

[doug748]

Hi - I am hoping this maybe a straight question.
I have an Icom IC M 423 dsc radio which can link up to an Ais unit - does it have to be of a Icom manufacture or can I use any other make ?
Jon

Further to post 13, I am not entirely sure I have an ICM 423 but mine looks exactly like your model, so I think it is.

It does connect and work with my Vesper Watchmate 850. There is a good chance that this company will have developed products with a similar level of compatibility.
They are usually pretty good at attending to questions: WatchMate Vision Class B AIS Transponder | Vesper Marine


PS,

I have just noticed that a graphic illustrating the new Wachmate Vision 2 shows the unit connected to a VHF that looks uncannily like the Icom.

.

 

[laika]

The Icon AIS radar outputs AIS messages so when connected to the OP's Icom Radio and the Icon AIS manual confirms it outputs NMEA @ 38440. so the Icon Radio must receive the AIS messages @ 38440.

The DSC input NMEA message is @ 4800 so will be on a different input connection which it is.

With the acknowledgement that I own none of these so could easily be wrong...the 423 only appears to have one nmea-0183 input and no mention of a way to change the baud rate. We know it receives DSC messages so the implication is that the nmea-0183 connection *out* from the MA500 is the one which outputs DSC (as well as GPS) which defaults to 4800 and doesn't output AIS. I don't see any mention in the 423 manual about it doing anything with AIS if it did receive it (ie allowing targets to be selected for individual calls like I suspect your standard horizon one does). For these reasons I don't believe that the 423 is intended to receive VDM sentences from an external AIS unit

I could be quite easy to write an add on to OpenCPN to send a DSC message out on a seperate RS232 or USB/RS232 to the separate input to the Icon radio.

I'm not sure the structure of the DSC message for setting up an individual call has been sufficiently publicly documented which is why it would be great if someone with something which *does* set up DSC individual calls could tap off another listener on a PC, see what the sentences look like and fill in the gaps in the doc I posted earlier.

 

[rogerthebodger]

Yes it looks like the OP's radio does not receive or display and AIS data so cannot on its own send a DSC call without manually entering the MMIS no of the target.

This can only be done by he addition of the Icon AIS.

What can be done is to connect to a chart plotter that has the capability of outputting the DSC /DSE call message to the radio.

I have somewhere the message formats will have a look later.

 

[laika]

I have somewhere the message formats will have a look later.

If it's more comprehensive than the link I posted in #18 I'd certainly be very interested to see it

 

[PaulRainbow]

Re reading my post I can see as I did not make it clear. I ment connecting to the OP's the Icon radio

I have a SH 2000. This require a AIS input and as I already had a NASA AIS engine feeding my OpenCPN via a USB Rs232 converter I did not need a radio which included an AIS receiver. I already has a RS232 GPS mouse lying around so I used that to feed GP into the radio.

Also I use NavMonPC to combine the incoming messages for OpenCPN and this has a AIS radar type display I did not need a seperate display. The NASA AIS engine feeds both the SH radio and the OpenCPN. I Also have a USB GPS muse for OpenCPN. My PC which runs OpenCPN has a screen both in the cockpit and at the nav station where the main SH radio is located and a RAM in the cockpit.

All clear now, thanks.

If the OP needs that funcilaibility thn fine but I personally don't think its too important as the radio has that function anyway. Also the Icon unit is a AIS transmitter as well as a receiver. Again dies the OP want that function. To me the AIS receive and display is more important considering the extra cost of an AIS transceiver

The Icom AIS radar outputs AIS data in NMEA format at 38440 so the OP's Icom radio must be able to receive the AIS data at that speed. So it must be able to receive AIS data from any other device that output AIS data at 38440.

The Icom AIS outputs AIS data at 4800 or 3400, for display on a chart plotter etc. It also outputs "something" at 4800 which initiates a DSC call to an AIS target, on specific Icom VHF sets. It's not entirely clear whether the "something" is a standard sentence or PGM, or something proprietary, because the feature will only work with very specific Icom VHF sets. It could simply be that it is a standard message and most VHF sets are not configured to act on the message.

The Icom IC-M423 only has a single input/output port. This is only for receiving the message to initiate the DSC call, it doesn't listen for any AIS data and has no way of displaying it in the way your SH VHF does.

I agree that it has limited use. It's a nice to have feature, but would be used very rarely and i wouldn't want to sacrifice other functionality or convenience just to have it. I think it's more important to have the AIS display on a chart plotter/MFD/OpenCPN etc.

For the money the Icom costs i'd rather have a better AIS. It's a dated unit that only uses NMEA 0183 and is on the "older" AIS format, transmitting at 2w etc, rather than the SOTDMA format, which amongst other things transmits at 5w. For the same money an Emtrak B900x AIS could be purchased with SOTDMA, NMEA 0183, N2K, USB, built in GPS (including antenna), built in splitter etc.

 

[PaulRainbow]

(QUOTE=""]
I could be quite easy to write an add on to OpenCPN to send a DSC message out on a seperate RS232 or USB/RS232 to the separate input to the Icon radio. I considered this but my old SH does not accept the DSC input message so no point for me. I don't see it as that important as I do have a RAM in the cockpit.

The question is "does you radio accept a DSC message that will cause it to make a DSC call without any manual input to the radio. If it can than an add on to OpenCPN can be written to do that function by selecting a target and initiating a call from the OpenCPN screen

I wonder why no-one else has written an add on ? But then, there are very few VHF sets that can make the call, so that limits the target audience. Additionally, OpenCPN only works with NMEA 0183, so more limitations.

It's also still unclear whether standard messages are being used, or proprietary. In the early days it seems like they were proprietary, but that may have changed.

There is a discussion on Panbo, but it's 5 years old: Direct DSC VHF calls to AIS targets, a NMEA 2000 standard?? - Panbo Forum

 

[rogerthebodger]

Paul

Thinking about a Radio sends a DSC format message over specified channel channel so it would be a very simple piece of software to allow the radio to receive a DSC message in the same format that it send out and for forward the VHF received message back to the originating device.

This means no special format. It's just some software in the radio to forward the received message either NMEA 0830 or 2000

You right the ability to send a DSC message from a chart plotter is a nice to have but to me it better from the radio with the ability to pick up the MMSI from the chart plotter or AIS receiver.

For the OP the only to improve the functionality of his radio is to either have a chart plotter/AIS that could send a compatible DSC message to the radio

this lack of proper functionality of the OP's Icom is a problem but would need the OP to replace his radio.


OK guy this has been discussed before

Calling an AIS target on VHF without entering the MMSI manually

Bottom of Page 36 as posted by prv in the above thread,

http://www.plaisance-pratique.com/IMG/pdf/NMEA0183-2.pdf

So the same message format can be used to to provide data from a radio to make a DSC call if the radio has that facility.

 

[jon and michie]

Right may I say thank you very much to everyone who has replied - a lot to get my head around but getting the jist on the information.
As I said in my first post I may/may not get an ais unit but this thread has given me food for thought.
thanks again
Jon