NMEA baud rate conflict with AIS and VHF/radar. Solutions?

vyv_cox

vyv_cox

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Today, taking advantage of distinctly non-Greek weather, I have managed to get my new GPS plotter to talk to VHF, radar and AIS. Problem is that two of them want a baud rate of 4800 and the other wants 38000(approx)

Is there a cheap and simple way of doing this? At present I can select one or the other from the plotter but this has clear disadvantages. Having spent a small fortune on the upgrade I am hoping for something that doesn't cost the earth. Thanks for any suggestions.
 
Hi vyv,
I understand from what you wrote that the Plotter is the listener?
The VHF is a listener (position for sayDSC)
The radar is a talker( overlay on Plotter)
The AIS is a talker( overlay on Plotter).
Is this the way it seems to you?
Once we get the layout in our heads, more to follow!
 
Seems I should have added lots more info!

The plotter is a new B&G Zeus2. It is talking to a Standard Horizon GX1500E VHF, and an old Raymarine E70 radar. The radar is not required to communicate with the plotter and has not been used in anger for years. The plotter has output and input to/from an Icom MXA-5000 NMEA 0183 AIS receiver. We only need AIS rarely and this was a cheap and convenient way to obtain it.
 
I'm not clear in which direction your communication problem is, but the ICOM AIS can multiplex a 4800 input onto the high speed output, does that offer any possibilities?
 
vyv_cox said:
Seems I should have added lots more info!

The plotter is a new B&G Zeus2. It is talking to a Standard Horizon GX1500E VHF, and an old Raymarine E70 radar. The radar is not required to communicate with the plotter and has not been used in anger for years. The plotter has output and input to/from an Icom MXA-5000 NMEA 0183 AIS receiver. We only need AIS rarely and this was a cheap and convenient way to obtain it.
Click to expand...

Unfortunately, the NMEA0183 port on the Zeus2 can only be set to the same speed for both input and output. So it has to be set to 38400 baud to accept AIS data. Probably the cheapest solution is to add a cheap GPS receiver to supply position data to the radio and radar (if it needs it). If you want the DSC output from the radio to go to the plotter, you could feed it in to the Icom AIS receiver and its internal multiplexer will pass it on to the plotter at 38400 baud.
 
Plevier said:
I'm not clear in which direction your communication problem is, but the ICOM AIS can multiplex a 4800 input onto the high speed output, does that offer any possibilities?
Click to expand...

I can wire up NMEA if the handbook's written for simpletons, but am by no means even vaguely expert.
However, my experience with my set-up might help Vyv, or perhaps someone else, along the lines Plevier has mentioned:
Lowrance HDS plotter with single NMEA 0183 port (B&G plotter is from same company and will probably have similar characteristics...but maybe two 0183 ports?).
Radio Ocean RO4800 VHF/AIS receiver.
Raymarine ST6000+ steering.

Plotter is required to listen to VHF for AIS info and talk to the ST6000. OK. But obviously one is 4800 baud, the other 38,400, so that doesn't work. However, buried in the VHF menus is an option to output AIS at 4800. Select this option and you get a warning that it may not work. However, it does work: displays accurate AIS info whilst still talking efectively to auto-steering.

There's also 'broadband' radar on my set-up, but this is via ethernet so not relevant to Vyv's devices.

Apologies if this is too banal to even be worth mentioning.
 
You won't be able to squeeze much AIS data into 4.8Kb, because of the size of the sentences, so you'd really need to forego AIS if you want to use 4.8K
 
vyv_cox said:
Seems I should have added lots more info!

The plotter is a new B&G Zeus2. It is talking to a Standard Horizon GX1500E VHF, and an old Raymarine E70 radar. The radar is not required to communicate with the plotter and has not been used in anger for years. The plotter has output and input to/from an Icom MXA-5000 NMEA 0183 AIS receiver. We only need AIS rarely and this was a cheap and convenient way to obtain it.
Click to expand...
Hi again VYV and OP's,

This spec talks of a built in multiplexer, may help?
http://www.icomamerica.com/en/products/marine/ais/mxa5000/default.aspx
So route AIS through the VHF and thence to plotter?
Plevier mentions this before me!

PVB seems to have the best handle on your setup, so I'll drop out now!
Hope you get there soon, I'm doing all this next visit out to Marseilles, but different gear.
 
Last edited:
pvb said:
Unfortunately, the NMEA0183 port on the Zeus2 can only be set to the same speed for both input and output. So it has to be set to 38400 baud to accept AIS data. Probably the cheapest solution is to add a cheap GPS receiver to supply position data to the radio and radar (if it needs it). If you want the DSC output from the radio to go to the plotter, you could feed it in to the Icom AIS receiver and its internal multiplexer will pass it on to the plotter at 38400 baud.
Click to expand...

Thanks, that was my thought also. Any suggestions for the 'cheap GPS?'

Thanks for the other contributions. The radar needs GPS input for MARPA and for waypoint but we use the set very rarely now. I can choose to have either AIS or DSC VHF and radar by changing the baud rate on the plotter.
 
pvb said:
See post #8.
Click to expand...

Yes, I realise both input and output of a specific port will be the same baud rate, but according to the on line instructions I read there are two input and two output ports. Hence my suggestions that input A and output A could be at 4800 whilst input B and output B could be 38400. Post 8 does not refer to two ports.
 
Keith-i said:
Yes, I realise both input and output of a specific port will be the same baud rate, but according to the on line instructions I read there are two input and two output ports. Hence my suggestions that input A and output A could be at 4800 whilst input B and output B could be 38400. Post 8 does not refer to two ports.
Click to expand...

The Zeus2 has a multitude of ports for every imaginable application but only one NMEA 0183 port.
 
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