Monday, August 20, 2007

AIS ship tracking

AIS, or Automatic Identification System is not much unlike APRS - it is a professional tracking system for ships. It runs at 9600 bit/s (GMSK) on two marine VHF frequencies, with a nice binary protocol which features automatic synchronization and time multiplexing - even with a very high number of vessels transmitting position reports once every 2 to 10 seconds, packet collisions will not be a problem. The protocol is standardized and well-defined, but unfortunately patented.

Fortunately the protocol is unencrypted and available. There is a Windows application called ShipPlotter which can decode AIS traffic and export the received position reports using HTTP. If you live somewhere near a coast, set up a 160 MHz FM receiver with a discriminator output or data port (you can't properly decode 9600 bit/s from the audio output of most FM receivers), plug it in the sound card of your PC, and you can track ships from miles away. A single receiver on the south coast of Finland can hear ships from Tallinn and a good part of the Gulf of Finland.

Now, can receive the HTTP position report exports sent by ShipPlotter. If you run it somewhere on a 24/7 basis, please get in touch with me and share the view with others! There's currently one receiver feeding us with AIS traffic from Helsinki, Gulf of Finland (thanks Tapio!).

To see some AIS traffic, zoom to the area between Helsinki, Finland and Tallinn, Estonia and make sure you have enabled viewing AIS data in the Options!


Ian said...
This comment has been removed by a blog administrator.
prt3 said...

Hi Hessu,

I would like to start experimenting feeding AIS data from Montréal, Canada to

Please provide directions.


Pierre Thibaudeau

oh7lzb said...

Hi Pierre,

I've emailed the instructions again. It seems that the email was lost on the first time (Sun, 6 Jan 2008).

Pierre T. said...

Hi Hessu,

At last, I now have a working setup on a computer that has enough power so
I can let it run full time. The following URL is a good starting point to
view the current coverage of my receiver.

if you wish to add a link to

'73 - Pierre
Montréal, Québec, Canada

Pierre Thibaudeau

Anonymous said...

I would like to feed some AIS data to, but I can't find any info how to do this. I'm currently using AISMon in my home location and would like to set up an AIS receiver in club station to share AIS data on Can you send me an e-mail on this subject?

Thanks and best regards


(substitute (2) with @)

Martin Waller said...

Hello Jed, I run in the UK and I'm always interested in anyone wanting to share data with me. I run the site purely for pleasure and not profit.


LA4ELA Tormod said...

I would like to start experimenting feeding AIS data from Lovund, Norway to

Please provide directions.


LA4ELA Tormod

Erik said...


Started with test AIS from Andenes, Norway.
Instructions for feeding through


SW2HUI said...
This comment has been removed by the author.
OD5RW said...

Hi Hessu,

I would like to feed some AIS from the eastern mediterranean

Please provide directions

John, OD5RW

Eric said...

I live in Newport News, VA and could probably hear a lot of the traffic coming in and out of the Chesapeake Bay. Is there any scripts out there for Linux that I could run and have it port the information over to your server?

oh7lzb said...

I'm working on gnuais, I have it running here at home already, just need to write some glue code to make it talk to I'm committing my changes straight to the SVN repository of gnuais.

Tore said...

Would it be possible for you to monitor and locate the radio communication from the missing ship Arctic Sea? Located somewhere in the Atlantic.


oh7lzb said...

Tore: Some AIS position reports have been received, and everything is shown that we have. The last position is probably fake.

Carmelo said...

I have a AIS RX on board of my sailboat, now sending data to and, but not with Shiplotter.

I have a RS232-IP converter and one router 3G with Internet access.

If you give me an port number and IP address, can you put my data in