AIS partner wanted

[DXAdriatic]

If anyone would like to share AIS data,please check with Become FleetMon AIS Partner
Lot of amateur radio operators and SWL's do share with them and everyone is welcomed. They are looking for partners around the world.They provide free receivers Comar R400N.It has great reception! Nice site as well.

 

[Ubbe]

That's pretty much the same as MarineTraffic.com
Not having a great place for monitoring but I still got a free receiver and Sirio 5/8 antenna and the coax length needed from MarineTraffic. Their receiver has WiFi so easy to connect.

/Ubbe

 

[K5MPH]

That's pretty much the same as MarineTraffic.com
Not having a great place for monitoring but I still got a free receiver and Sirio 5/8 antenna and the coax length needed from MarineTraffic. Their receiver has WiFi so easy to connect.

/Ubbe

I have the same setup I have been providing AIS data for MarineTraffic for years now in my area .........

 

[adsbgreenock]

I too have a marine traffic SLR350i comar device and GPA colinear antenna.

I have several commercial Comar R500NGI and R400N receivers at different locations in the UK.

Truth be told though after rigorous testing..

The commercial receivers ain't got a patch on and RTL Blog V3 sdr Raspberry pi and Jasper's AIS-catcher Advanced decoder/NMEA router.

Since using AIS-catcher my message rate has increased tenfold and maximum range has superceded the commercial receivers by at least 10nm.

Jasper's decoder can utilise multiple devices including AIRSPY, SDRPlay, Hackrf, RTL-SDR,.

Easy to setup on windows (includes a batch program for those not fond of the command line)
, Linux or Raspberry os.. There is even an android app which is soon to hit the Google playstore.

The advanced decoder let's you timestamp and manipulate data, even showing the signal strength of AIS messages. There is even the option to decode Long Range (Class A vessels) AIS which is used by satellite.
Forwarding your nmea data to your chosen sites either by using internal commands or send it to aisdipatcher via udp local.

Check it out here guys :

GitHub - jvde-github/AIS-catcher: AIS receiver for RTL SDR dongles, Airspy R2, Airspy Mini, Airspy HF+, HackRF, SDRplay and SoapySDR

AIS receiver for RTL SDR dongles, Airspy R2, Airspy Mini, Airspy HF+, HackRF, SDRplay and SoapySDR - GitHub - jvde-github/AIS-catcher: AIS receiver for RTL SDR dongles, Airspy R2, Airspy Mini, Air...

github.com

Regards

 

[Ubbe]

Since using AIS-catcher my message rate has increased tenfold and maximum range has superceded the commercial receivers by at least 10nm.

I tried AIS-catcher just now and used a RTL_SDR v3 and auto for gain as well as the optimum gain settings I use in SDR# and the SLR350Ni see ships further out than the RTL_SDR. I believe I saw a bandpass filter in the 350 box when I took a peek, and where also using standard 820T2 chip, and that seem to increase sensitivity compared to a "naked" RTL_SDR running from the same antenna splitter that uses a FM broadcast filter.

/Ubbe

 

[adsbgreenock]

Hi Ubbe,

I have noticed with marine traffic there is filtering going on somewhere but couldn't quite put my finger on it. I thought it was happening on the website.

I'm glad you possibly noticed this bandpass on the actual receiver side. I was looking for something (anything) to adjust the gain as its the same ais reciever module in most of the comar commercial receivers (R400N is the same too)

Station 1 :
Marine traffics own setup SL350Ni shows traffic at a a maximum of 22nm

Station 2 :
rtl-sdr v3 blog (same antenna, pl259 splitter no preamp or LNA running AIS-catcher with the below parameter :

AIS-catcher -gr tuner 48.0 rtlagc OFF -u 127.0.0.1 12345

This sets rf gain to almost maximum as you will know, and routes the stream to aisdispatcher udp web server .

Available rtl-sdr gains for everyone's reference:

0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6
19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4
37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6

Using -10 (or rtl-agc ON in AIS-catcher) set AGC automatic gain control to ON which isn't ideal for most applications, this will cause distortion of signals.

This rf gain setting at 48.0 seems to suit my sdr dongle setup and terrain in the area with no real interference from MW or other commercial stations normally requiring notches.

Station 2 With the RTLFleetmon shows more class B vessels (compared to Marine Traffic) as well as more vessels Almost 40-42nm away.

Normally i would put this down to atmospheric ducting on the short term Ubbe. However, these amazing results have only appeared since using Jasper's decoder.

The conclusion appears to be having a more advanced decoder and higher nmea message rate is allowing more class b signals to be processed and displayed on the map. With an adjustable rf gain ( as opposed to the commercial receivers fixed gain) this also seems to increase the decode and overall range.

Hopefully more people can try this out as and see if they can notice a difference.

Regards

 

[Ubbe]

I've experimented with different gain settings but can't improve the coverage. But what is within coverage seems to be more vessels. I can see a ferry carrying cars over the canal in AIS catcher that I've never seen in the SLR350 map. I have to go to MarineTraffic map to see it. The same type of ferries at other places are shown ok in the 350.

There's lots of passenger ships at the outer edge of the 350's coverage that are never seen in AIS catcher, but then there are sailboats closer to me in AIS catcher that doesn't show on the 350 map. I had a rescue helicopter in air and it disappeared very quickly from AIS catcher but was tracked much longer in SLR350.

There's only 5-10 msg per second so should be plenty of time to handle all info in the 350, so I don't know why there are some vessels not showing on the map. MarineTraffic have sent out a new SD card to me with a new program and I will try that to see if the problem is fixed.

/Ubbe

 

[adsbgreenock]

Hi Ubbe and all ,

Yes I see what you mean , conditions and terrain as well as antenna type/height come into play plus many other aspects.

If you have a seperate home brew setup (not the MT or fleetmons own)A good reference site to check stats (real time ) is the site

My Ship Tracking Free Realtime AIS Vessel Tracking Vessels Finder Map - ship tracker

My Ship Tracking is a FREE REALTIME AIS vessel finder tracking service. With this vessel tracker you can monitor ship positions, vessel tracking, ship tracking, vessel position, vessels traffic, port activity in realtime map.

myshiptracking.com

This will show you what's coming out the other end to a high standard with graphs and other scales / measurements and give you an idea how the gain is working for you.

I am currently playing around with an SDRPlay RSPDuo as my AIS receiver but the RTL - SDR seems to be more suited as its not as clogged up with commands, settings and switches in the AIS-catcher program .


Regards