Receiving AIS Signal ?

[St. Elsewhere]

gleff,

Good luck with your project.

You should read through the information here: Cover your Area on the Live Navigation Map. It is from MarineTraffic.com and covers information on AIS antennas, and equipment to become a base station to support their system. Sydney already has quite a bit of coverage, but it may be helpful to you for your own objectives because it discusses improving signal reception.

Also, there was a notion in an earlier post that base stations may act as repeaters. I do not think that is the case. I think that they receive AIS signals, and put the data on the internet, or in the case of vessel traffic systems, collect it for traffic controller displays.

[gleff]

Okay.. I have an update... I got my new antenna about an hour or so ago. I plugged it in, through it out on the balcony next to the bbq (not mounted on the railing), and proceeded to tune into the AIS frequencies on the SBS-3 virtual radar. In AM mode where I was expecting to hear transmissions (blips, pops, etc) were non existent.. although I was picking up loads of harmonics of voice stations around. I then put it on FM which is where it needs to be to decode AIS and again, heard absolutely nothing but static.

Thinking the entire situation was a waste, I loaded up shipplotter.. pressed start (didn't configure anything), and looked at the message section.

LOW AND BEHOLD.. I'M DECODING AIS MESSAGES!!!!!!!!!!!!!!!!!!

Preliminary findings is that it's a bit flakey and i'm getting around 5nm in distance but this is rather expected. I may be able to improve on this by changing the cable, and mounting the antenna properly on the railing.

Here are a few messages I've received so far.

311513000;moored ;000°'; 0.0kt;33.861105S;151.200288E;176.0°;176°;30s;12012 3 081028;audio[3]
503601000;under way ;000°'; 0.0kt;33.860917S;151.210200E; 0.0°;194°;14s;120123 081112;audio[1]
503042600;unknown ;000°'; 0.0kt;33.807418S;151.248843E;149.2°;511°;37s;12012 3 081135;audio[18]
503344800;under way ;000°'; 3.7kt;33.856950S;151.196033E;156.4°;158°;49s;12012 3 081147;audio[3]
311513000;(9247144);(C6SW3 );SEVEN SEAS VOYAGER ;Passenger ;-> Jan23 17:45 SYDNEY ;205 28 7.0 11 14;120123 081253;audio[5]
351607000;moored ;128°'; 0.0kt;33.969198S;151.210958E; 0.1°;254°;03s;120123 081303;audio[3]
503344800;under way ;129°'; 8.0kt;33.860883S;151.197450E;158.1°;157°;36s;12012 3 081334;audio[3]
503344800;under way ;129°'; 7.9kt;33.861550S;151.197800E;156.3°;154°;56s;12012 3 081354;audio[3]
503075000;under way ;128°'; 0.0kt;33.855943S;151.189013E; 0.0°;511°;23s;120123 081421;audio[1]

The bottom line is I'm able to pick up AIS signals.

Woot. I'll have a ball with this on the weekend now.

Thanks to everyone for their input in the thread.

[christian.kautz]

Originally Posted by gleff

Okay.. .... LOW AND BEHOLD.. I'M DECODING AIS MESSAGES!!!!!!!!!!!!!!!!!!

shure, a good antenna ist the best way to good results. If u are satisfied - dont touch anything and enjoy! If u are looking for more - what about ur receiver? I use the ICOM PCR1000 - 1.choice what ever u want to monitor. There are several preamplfiers on the market - most are no worth a single buck! The enhance signallevel and noise - u have to enhence signal not the noise. Look for splitter(?) from a old DUPLEX VHF (maritime) radio. Maybe difficult to find, but it cuts down all the noise - except from the desired frequencies. Bandwidth is about 5 Mc, these radios transmit in the lower (157 Mc) at 25W and receive on upper (162Mc). Connect ur AIS to upper band, your VHF Voice receiver (if any) to lower.