How do I connect up an AIS engine?

Otter

Otter

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Couple of quick questions not covered in the "manual".

1. The VHF socket is a shape I've never seen before - anyone know what it's called so I can order the right plug?

2. The AIS is going into a Standard Horizon (180) for overlay on the chart. Do I need to feed GPS data from the plotter to the AIS and then back again? How does the plotter know where the AIS signals are coming from otherwise? Does the AIS signal from the ship contain a GPS position in the code?

Could have done with a bit more of a manual than a photocopied A4 sheet /forums/images/graemlins/mad.gif Still, it is simple enough.

Thanks for the help.

AIS%20ENGINE%202.jpg


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VHF socket is BNC. If you prefer you can use a PL259 on the aerial cable (same as the plug on your radio) and use a BNC/SO239 adapter to the AIS engine. This means if you lose your main aerial you can use your AIS aerial as back-up for your vhf radio.
 
Thanks - is the socket on that AIS unit male or female? It has two studs on the outside of the metal sleeve.
 
You need a BNC plug - the fitting on the AIS engine is a socket.

AIS signals contain position data, so the plotter knows how to display targets.
 
VHF described above.

The AIS data is output as a NMEA sentence at 38.4kbaud. This needs to be connected into the plotter.

Conventionally, the GPS NMEA data would be sent at 4800baud and connected to a separate input on the plotter.

i.e. connect the AIS engine & the GPS to separate inputs on the plotter. The CP180 has enough for this from what I remember.

One thing the AIS engine will do is to take the GPS data & send it out along with the AIS data, both at 38.4kbaud on the same wires. You can do this when you don't have enough connectors on the plotter.
 
[ QUOTE ]
Conventionally, the GPS NMEA data would be sent at 4800baud and connected to a separate input on the plotter.

i.e. connect the AIS engine & the GPS to separate inputs on the plotter. The CP180 has enough for this from what I remember.

One thing the AIS engine will do is to take the GPS data & send it out along with the AIS data, both at 38.4kbaud on the same wires. You can do this when you don't have enough connectors on the plotter.

[/ QUOTE ]Sorry, but your advice is completely wrong and will only confuse the original poster. The Standard Horizon CP180 has a its own GPS antenna which connects directly to it - there's no need to feed GPS signals into it separately.
 
[ QUOTE ]
Does the AIS signal from the ship contain a GPS position in the code?


[/ QUOTE ]

Yes - amongst other things of course. There is no need to feed GPS to the AIS unit (the only reason its available as an option is if you wanted to say display it all on a laptop - obviously without a GPS the AIS would know where all the ships around you were - but not where you were - so couldn't tell you how close they are etc.

Most (all?) plotters that display AIS data will do this calculation in their own software
 
There will only be position in the AIS code if you feed it in to the AIS on the blue wire on the supplied RS232 cable (wire sticks out of main cable).

It is not needed to connect this wire up when wiring into a plotter, can be useful if wiring up to a PC as it means you get the position sentence along with the AIS data.

Maplins do a PL259 to BNC converter plug so you can plug a standard antenna in.
 
Yes indeed. You beat me to the edit.

The CP180 does have its own GPS receiver. Hence there is only one connection of AIS data required from the AIS engine to the CP180.

If the CP180 was a plotter that required a GPS input or a PC, my advice would have been correct.

To expand on what's in an AIS sentence, it can contain different data sets. With most NMEA sentences, you can almost read them as text and that's why hyperterminal is so good when you come to check NMEA into a PC. The AIVDM sentence is the NMEA AIS sentence and the data is encrypted so it looks like a load of random characters. You can check the sentence with hyperterminal but can't read the data. It'll look something like this:

!AIVDM,1,1,,B,19NS7Sp02wo?HETKA2K6mUM20<L=,0*27

The most common message has things like: MMSI number, SOG, COG, rate of turn, lat/lon, true heading, plus some other stuff.

Other messages have things like the vessel name, type of cargo, ETA. These are far less common.
 
When the plotter has an intergrated GPS, there is no need to feed GPS data to the AIS unit and back again. AIS data sets contain the positions of other vessels.
 
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