AIS on Northstar chartplotter

[cruisingmoon]

Hi all

I was here previously under another name - password now forgotten, and have got a lot of benefit as a lurker. Thanks.

Current boat project is installation of an SR161 AIS radio to my Northstar Explorer 557. I can get the AIS signal to my laptop (with a serial to USB adaptor), but with a cut serial cable, and just pins 2 and 5 connected, the chartplotter does not recognise any signal. (2 connects to red and 5 to shield.)

The baud rate differs between the two - the Northstar appears to be set at and immovable on 4800, and the AIS set at 38400 but adjustable via the hyperterminal programme on windows xp.

Unfortunately, I have windows vista and being a dummy, I am not sure that I am doing the right thing (in the "ports" item in the Device Manager), to make the change in the AIS.

Can anyone tell me what I am doing wrong, and set out some steps for me to make this thing work?

Many thanks, this time.

Jeff Robinson

[RBEmerson]

See page 69 of the 557/567 owner's manual (HERE) for the details. Long story short, based on what I see in the manual, you're headed for an interesting project.

[scotte]

AIS output is 38400 - if the chartplotter supports AIS input, then it supports input at 38400. If you also want to tie NMEA into the chartplotter, then you've got a couple of options - if your AIS receiver has built-in NMEA combining/echoing/multiplexing (i.e. NMEA input, AIS output), then you can use that; otherwise you'll have to go with a NMEA MUX that supports speed conversion.

On the output side, it just depends on what your chartplotter does - if the input and output BPS speeds are coupled, and you need NMEA output at 4800bps, then you should be able to use something like the Brookhouse AIS-C multiplexer, which has a speed-conversion loop (both input and output) for chartplotter use (designed for Raymarine C-series (thus the "C"), but really suitable for any device with the same limitations). If your chartplotter has decoupled input and output BPS rates, then you should be golden - again all this assumes you want NMEA output from the chartplotter (as opposed to AIS+NMEA input).

[Paul Elliott]

It is probably possible to drive the chartplotter NMEA input with the RS232 output of the SR161 AIS receiver -- if you can configure the chartplotter input for 38400 BPS. You would be connecting a single-ended signal to a differential input, so you would run connect the RS232 ground to the NMEA "-" input.

This isn't the greatest way to connect these things, and does give you potential noise problems, but it usually works well enough. I do prefer the NMEA multiplexer approach. ShipModul also makes some good ones for this application.

[RBEmerson]

Guys, read the manual. Northstar uses a proprietary cable for the AIS connection which, if I understand the manual correctly, leads to the correct port, which is not the generic NMEA I/O port, locked at 4800.

My first cut at a reply, before I RTFM , included the phrase "in a crowded environment, AIS at 4800 will break your heart". The length of any one AIS sentence and the frequency at which they're sent by any receiver will swamp a 4800 port, with resulting problems and frustration. In short, forget it.

It appears, however, that Northstar/Navman left a backdoor open for AIS but you need their combined Fuel Management/AIS (what sort of combo is that???) cable to start the process. Frankly, this is a good argument for dropping this plotter like a hot rock. But since it seems Cruisingmoon is stuck with it, I guess he's gonna have to play along.

If only he'd talked to us before buying the thing...

[sandy daugherty]

There's no information on it, but apparently NorthStar (Navman) can accept SOMETHING about AIS on its Navnet port. The website calls for part no. AA002458, but says nothing about data rates. They do say the Comar 200 works, and it has a 38400 output, right? It bothered me that they listed the NASA set, which advertised a 4800 baud connection but utterly failed to deliver.

[RBEmerson]

Y'all are hitting reasons why I said putting a AIS receiver on this plotter could be ...ah... interesting. There's nothing in the manual about 38400, 38,400... nada. Just comments that NMEA is inferior to Navnet and "see your Northstar dealer".

Clearly, the plotter can comprehend some form of AIS activity, or that's how the manual paints things. But the nitty gritty details? Nah...