I wrote this for people who want to use an existing radio
as an AIS
receiver. In other words people who like to do things the hard way. The easy way is to buy a dedicated AIS
receiver and plug
it in. The hard way, my way, involves finding a suitable radio
or modifying an unsuitable one, getting three additional software
programs, two of which are not used as their developers intended, then getting it all to work together. It is not overly complicated but rather involved. I am using 64 bit Windows Home Premium.
I am going to start by assuming you have a suitable radio. I avoided the whole problem by using my Icom
706 which has a data port for digital data. If you want to persue radio modifications try here: lDiscriminator Output
The first step is decoding the raw AIS signal, via your computer's sound card, into a NMEA
data stream that OpenCPN
can understand. For this you need AISMon. Go to groups.yahoo.com/group/aismon/
look under "Files" and download "AISMon_2.2.0.exe" and "LA_LB_Snippet.wav". The wav file will be used for testing. Note that you will have to register in order to access this site. Install the software
Now we have a NMEA
date stream. Unfortunately AISMon and Opencpn
will not talk to each other directly. We need some Virtual Com ports
. This part took half a day of internetting and fiddling around. The favorite software, VSPE, that people used in the past will not work with 64 bit Windows 7 unless you get the paid version. In one of the forums
someone mentioned NavMon which is a program for displaying GPS
and AIS data but also has the ability to create virtual ports
. This is the way I went. Go to www.navmonpc.com
and under "Downloads" get "Version 1.13 Setup". Get the four user guides as well as this program does much more than creating virtual ports. Alas the virtual port feature does not work with 64 bit Windows either but there is a patch. Go to GpsGate Client - Products - GpsGate.com
and download "Free GpsGate Client For Windows". GPS
Gate Client is intended for sending data from one GPS to several programs but it integrates itself into NavMon. Install GPS Gate Client first then NavNon. NavMon will ask if you want to install Franson Serial
Tools. Say no, this is what the patch fixed. If, perchance, you have already installed NavMon on your computer you have to uninstall it and the Franson drivers before doing the new install. See NavMonPc User's Guide Supplement 1.13 for more information. Incidently NavMon has an active users group at NavMonPc : NavMonPc Gen 2
Now for some configuring. Close everything down then open NavMon. Go to "File/Connections/Virtual Port A,B,C". Virtual ports are on the left. We need two ports. Set "Virtual Serial
Port A" to an unused Com port number (I used 7). Click "Connect" and tick the "Autostart" box. Do the same for Port B using a different Com Port number (I used 8). Open OpenCpn. Under "Tools/AIS" in the "AIS Data Port" drop down menu select one of your Virtual Port numbers (I picked 8). Open AISMon. Tick the Serial Output box, set the Com Port to your other Virtual Port ( 7 ) and set Baudrate to 38400.
Now to see if it works. In AISMon click "Replay File" and navigate your way to where you stored the LA_LB_Snippet.wav file. AISMon should show the following under Demodulator Counts, Syncs: 103, Valid: 99 96%, Errors: 4 4% if it is decoding properly.
Open up NavMon. Click "AIS" on the Tool bar. Click on the little "AIS List" box. If the Virtual port configurations are still visible click "Done". Now go back to AISMon, replay the wav file and click "Start Monitoring". The NavMon AIS Status box should go green and say 39 targets. Also you will get a listing of all the 39 targets.
Open up OpenCpn and head
to Los Angeles (33deg42min N, 118deg15min W). You will see a bunch of yellow triangles (Ships!). Everything works.
Because the data input is not continuous after a few minutes the programs consider the data out-of-date and it will disappear. Go back to AISMon and replay the wav file.
Note that no changes are necessary to any of your GPS input settings.
After a fresh boot open NavMon first to get the virtual ports started, then AISMon and OpenCpn. GPSGate does not need to be started. However it starts itself when the computer boots. I thought this was rather presumptuous of it and disabled it's autorun function.
After connecting an antenna
to the 706, tracking down a corroded audio connector and adjusting the volume settings everything worked. May you be so fortunate.