At the other end of technical challenge, this is the local traffic (2 nm away), “caught” by using the most basic whip antenna that came with a DVB-TV stick and an rtl-sdr.com dongle.
Yesterday a French naval vessel sailed into town which I followed on my AIS setup. No surprise, a NATO exercise has been underway and a port call/shore leave for the crew would be in order. By chance a few hours later I had the map zoomed out far and saw a vessel off the west coast of France. It was the same one I tracked a few hours later. I then watched as the position ping-ponged back & forth between its actual location (Stockholm) and what I assume is its home port (Brest). Maybe this is the Franch Navy’s new low-cost stealth technology??
1 Like
MARINETRAFFIC.COM. I live in Southport North Carolina on the Cape fear River, and have numerous ships transit pass my home on the way to Wilmington North Carolina. After one passes if it interest me, I look it up on www.marinetraffic.com.
N2AOO
Navy vessels are not obliged to use AIS, and when they do it’s often with arbitrary or non-specific names. You are probably seeing two different vessels which are using the same MMSI. That’s not normally a problem since it’s only local vessels that would be making use of the data.
I don’t see how it could be two different vessels in this case. My humble setup cannot see the ~2000 km to Brest and when an icon disappeared from my map in one location it immediately appeared at the other. I am guessing it is a poorly cconfigured or operating device.
Ah if it’s data you are seeing locally then it’s unlikely to be two different ships. It could be just bad data being transmitted or maybe a decoding error.
Yes, my original post may not have been clear that the five stations reporting the vessel in port at Brest are all located in Stockholm. A very unlikely occurrence to be real. Further to your point that navy vessels use arbitrary identifiers, I see that a lot. I think this case of bad positions is another part of that equation - the military does what it wants, intentionally or unintentionally, because, well, they are the military. Who can argue?
I have a USB GPS that is giving position info to PiAware via GPSD. I also have GPSD setup to share data via network on port 2947. How would I setup AIS-catcher to use GPS data?
I tried:
-r txt 127.0.0.1 2947
-N share_loc on
This results in crashing AIS-catcher.
● aiscatcher.service - AIS-catcher
Loaded: loaded (/lib/systemd/system/aiscatcher.service; enabled; vendor pr>
Active: activating (auto-restart) (Result: exit-code) since Wed 2023-05-24>
Process: 7446 ExecStart=/bin/bash /usr/share/aiscatcher/start-ais.sh (code=>
Main PID: 7446 (code=exited, status=255/EXCEPTION)
CPU: 89ms
gpsd is not directly supported but you can read in the NMEA GPS data via gpsmon, using something like:
gpsmon -n -a | AIS-catcher -d:0 -r txt . -N 8100 share_loc on
-
gpsmon -n -awill print the GPS NMEA lines to screen -
-d:0starts the first SDR for AIS decoding -
-r txt .will read NMEA lines from standard input, in this case the GPS NMEA messages -
-N 8100 share_loc onwill start the webserver and will mark the location of the station.
The latest edge version has an experimental feature that would allow to run without gpsmon:
AIS-catcher -d:0 -t gpsd localhost 2947 -N 8100 share_loc on
Thanks for the information! I tried with gpsmon but that didn’t work. I haven’ tried with the latest edge version. Will give it shot.
2 Likes
So its been over 24hrs since I changed the antenna and as you can see below on my weekly stats graph, the Yagi has had a good impact on reception.
4 Likes
Marine AIS is VHF frequency about 162 MHtz and I only get a range of maximum about 30 nautical miles from my station that is located at an altitude of about 50 meters less than a mile from the ocean. Unless you get an aerial specifically for this frequency, you are unlikely to get more vessel transmissions. Higher aerial and closer to the sea is the best solution.
My attic has several antennas for ADS-B, AIS, and FM at about ~33 meters asl. There are large oak trees all around. I’m 6 nm from the Gulf of Mexico and 17 nm from the Port of Tampa. Peak range is 30 nm but more typically 20 nm. I have a 46" VHF antenna coupled with a Comar R400N AIS receiver all on loan from Jakota Cruise Systems (Fleetmon.com) in Rostock Germany. I’d like to move the antenna outdoors, but restrictions do not allow it.
If you cant move the antenna, then move to another house where there are no restrictions 
I have the same problem…everything, including antenna, has to stay indoors. Nothing allowed on outer wall or roof, or projecting out of window, and I dont have any balcony either. 
What, you’ve got windows? 
1 Like
Yes I have got windows, debian, and ubuntu
Yes, I have got large windows with glass panels. Luckily the glass panels are non-coated type, so no rf attenuation.
3 Likes
Hi All
So I have just ordered a VNA from Amazon that should be here tomorrow as I got some Overtime in last week and for £56 I though why not. Now Im going to test my yagi that I retuned to see how well (prob bad) I did from changing to 2m to 162mhz. I have been looking online recently and I think I have the VSWR sorted. What start/end freq do I need to input to see how well its fairing on AIS 162mhz? do I start at 161.500mhz and end on 162.500mhz and place the cursor on both the AIS channes at 161.975 & 162.025 and look at the VSWR number?