AIS receiver and NMEA 0183

Bosun Higgs

Bosun Higgs

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Does anyone know of an AIS receiver that outputs on 0183 at normal speeds rather than the usual superhogh ones?

I have a Raymarine C80 plotter and I can either have high speed AIS inputs or low speed 0183 inputs - not both together. Do as well as an AIS set I also need a multiplexer apparently. Which costs.
 
Garmin, N2K + 0183 at high and normal baud rate, AIS300 recieve only, AIS600 transponder.
Recently fitted one (transponder) interfaced to a C120 Classic for a customer for just the same reason, nice piece of kit.
 
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Don't think the RL70 is AIS capable (please check as I may be wrong) but basically any AIS capable plotter with N2K or 0183 should work with the AIS300 provided it has a spare 0183 in port or is on an N2K network, in which case it's plug & play. It's also worth a mention that some kit when sold had no AIS capability but has had subsequent software releases that make it capable so that's always worth checking.
 
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David2452 said:
I can see no benefit of such a device, unless you actually meant it the other way around.
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Are you referring to my post? If so, from my understanding of BH's problem (apart from being almost discovered) the benefit would be...

He needs everything at either 4800 baud or 38400 baud.
He has devices that transmit at both 4800 and 38400
So if the 4800 baud could be converted to 38400, everything is now at 38400.

Going the other way may be much more difficult, because there may be too many messages coming in at 38400 baud to fit them all in an output of 4800. In that case software would have to detect this case, queue the incoming messages, and discard some. Whereas going the other way is simplicity - when a byte comes in, spit it back out at the higher speed.

Just re-read what he needs - multiplexing as well. So a YAPP with 2 inputs (4800 and 38400) and one output (38400). This could still be done, but needs some more software to queue all the incoming messages and send them back out when there's time. There's a possibility of some messages having to be discarded, as with all multiplexers.

A PIC 18F26K22 has 2 UARTS and is quite cheap at under £3. One could be run at 38400 for the input and output at that speed, the other at 4800 for the input at that rate.
 
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Yes I was, problem is here is that most AIS transmists at the higher rate and that was the OPs origional issue, that is to say reducing the speed to be compatible with other talkers that will not transmit at the higher speed and the C Classics shortcomings. Of course the proposed device could be used on the other talkers and the AIS left at 38000. But as there is a simple solution alredy on the market, i.e. the multi rate Garmin engine which would future proof the install against fitting a later N2K compatible plotter at some stage I see no need to complicate the installation.
 
Bosun Higgs said:
Does anyone know of an AIS receiver that outputs on 0183 at normal speeds rather than the usual superhogh ones?

I have a Raymarine C80 plotter and I can either have high speed AIS inputs or low speed 0183 inputs - not both together. Do as well as an AIS set I also need a multiplexer apparently. Which costs.
Click to expand...

Been there, tried without multiplexer. Did not work.

I am afraid Raymarine C series Displays support AIS only at 38400 bps. Even if you find one that can output at 4800 the display will simply ignore the sentences received. Stupid Raymarine design.

Also you will need a Brookhouse multiplexer because it has the option to compensate the NMEA output signal to Raymarine specifications, with a different one I used to get frequent annoying alarms from the chartplotter "Lost AIS communication". I tried too to connect the AIS transponder NMEA output directly to the C80 NMEA input at 38400, removing anything else including NMEA GPS, because the transponder has its own GPS and provides position too. It worked for a while and got annoying intermittent "Lost GPS position" alarms and BTW ONLY WHEN SAILING, NEVER AT THE BERTH which made troubleshooting a nightmare. Then you wonder why I hate Raymarine so much!

I could help more if you specify which instruments you want to have in input/output with which NMEA bps.
 
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KevinT1 said:
Would the Garmin AIS300 work with a Raymarine RL70RC as well - it can be configured as NMEA0183 or Seatalk - or am I expecting too much ? :confused:
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No, the old Raymarine displays RLxxxx do not support AIS at all. I asked Raymarine, no way they will update the firmware!
 
haydude said:
Been there, tried without multiplexer.

I am afraid Raymarine C series Displays support AIS only at 38400 bps. Even if you find one that can output at 4800 the display will simply ignore the sentences received. Stupid Raymarine design.
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Simply not so, I heve done three now and all worked flawlessly with the AIS300 and one AIS600 set at at 4800. It should be noted that I had to upgrade the software on all three before I started as they were all quite old units and I don't think had ever had an upgrade since being taken out of the box, one wouldn't even do MARPA if I recall correctly. It is worth mentioning that the Raymarine AIS250 also has 4800 output but no N2K and a lot more money.
 
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haydude said:
I could help more if you specify which instruments you want to have in input/output with which NMEA bps.
Click to expand...

NMEA inputs to the C80 are just the heading sentence from the simrad pilot. Out puts are position speed etc to the simrad radar and the DSC radio. All the instruments are Raymarine working on Seatalk.
 
Do bear in mind that running AIS at 4800 baud will run into message overflow in areas with many transponders. This was the reason they switched to 38k4.
And when you want to combine with fast-heading output from the autopilot it becomes even more troublesome.
At 4800 baud you will only do about 500 Characters per second. The average NMEA message carries more then 15 characters, AIS messages a lot more.
 
Bosun Higgs said:
so after all this I'm still not sure how I can combine the various inputs I need for the C80 to use AIS.
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Well, the Garmin AIS300 which David2452 has recommended obviously works, because he says so. However, I'm not convinced that trying to push AIS data through at 4800baud is ultimately a good idea.

As an alternative (and at a similar price to the Garmin AIS300), you might consider a Raymarine AIS250 or AIS350. These, like the Garmin, include a VHF antenna splitter. The Raymarine products however appear to have a 2-way multiplexer operating at both 4800 and 38400baud. This would allow you to use the 38400 setting on your C80 for optimum AIS performance, and also still have 4800baud output to your DSC radio and Simrad radar.

You can get an AIS250 for around £330, or an AIS350 for about £30 extra. It would be worth phoning Raymarine first and clarifying that the equipment will actually do what you want it to do.
 
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