A couple of weeks ago I have bought a MarineGadget Radar AIS receiver from “Radar Gadgets” (http://www.radargadgets.com/). I have tested it and it works like a charm. It is easy to set up and to get it working. This article explains which steps you have to take to get this tiny device going.
If you receive the MarineGadget AIS receiver, you will get a large brown envelope, which contains the following:
- a CD containing the necessary drivers to get the device talking to your computer
- a USB extension cable
- an installation manual, which you will only really need for the commands you can send to the AIS receiver to configure it (more on this topic later in this post)
- and of course, a USB AIS receiver
You will need a computer with a free USB port and a marine VHF antenna. I have chosen for a laptop running Windows 7 Professional.
You will have to make sure that you will be able to connect the VHF antenna to the MarineGadget AIS device. The receiver has a female SMA connector for the antenna input, but it is delivered with a male SMA – female BNC adapter. The VHF marine antenna I own has a male PL-259 connector. Luckily, I have a male BNC – female PL-259 adapter, so I can connect everything together.
The work on the computer
Put the AIS receiver in a free USB port. Windows will try to find the appropriate drivers for the device, but that will fail. Ask Windows to search for drivers on the CD delivered with the receiver and voilà, the OS has recognized the device, has found the appropriate drivers and hence, is able to communicate with it. To make sure this action has been accomplished successfully and to find out which COM port you will have to use to talk to the device, open Start > Control Panel > Hardware and Sound > Device Manager.
Under the Ports (COM & LPT) branch of the devices tree you will notice that a new device has appeared: “MarineGadget Radar Comms Port (COM9)”.
We are almost there. As a serial terminal emulator program, I will use Putty. It is free and does its job well. Connect Putty to the COM 9 port using the following parameters (baud rate 38400 bps):
If you hit the Open button, AIS message sentences will start to roll over your screen:
One last thing, if you look closely to the image above, you only see channel B messages. The AIS receiver of MarineGadget can listen to only one channel at a time. So, you can configure it to listen to Channel A (161.975 MHz) or Channel B (162.025 MHz) continuously or you tell it to switch between the two channel frequencies at a regular time interval. How do you do this? When connected to the receiver with a terminal emulator, just type one of the following commands:
- RADFA: Channel A is set all the time
- RADFB: Channel B is set all the time (default)
- RADF1: Alternative Channel A and Channel B every 10 seconds
- RADF2: Alternative Channel A and Channel B every 20 seconds
- RADF3: Alternative Channel A and Channel B every 30 seconds
- RADF4: Alternative Channel A and Channel B every 40 seconds
- RADF5: Alternative Channel A and Channel B every 50 seconds
The receiver only demodulates AIS messages of these types: 1, 2, 3, 4, 5, 9, 18, 19, 21 and 24.