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AIS Vessel Tracking Sites


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Just curious how the AIS vessel tracking sites work?   Do they all share the same land base receivers or do they each have their own?
I tried to search for the same vessel on a few of the sites but only comes up on Marinetraffic.com non of the others. Do you have to register with each?
 

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There are two options, technically, for such things: terrestrial and satellite. As memory serves, 3 companies have terrestrial networks of any size and they swap data between them. While many would like to think the network is the asset, the satellite data is rapidly becoming more cost effective for the square miles covered for commercial use cases. The problem with satellite, as you might expect, is separating the noise is in noisy places like harbors where lots of radios are broadcasting at once.

The local receivers send the traffic from the host location to the server over the internet. The companies then build a database based on the traffic they see and augment that with user submissions to get pictures and such.

There is also fake AIS where the apps send your location to them. That data, as far as I'm aware, is not usually shared between the platforms and I'm not sure how popular it is.

You can build a listening station for yourself pretty easily. I had one in my office in Manhattan and it was kind of fun to watch the traffic fly by. I had planned to build a real time viz of sorts and never got around to it.

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Thanks for the info. I am monitoring a friend going down the east coast and was wondering why he was only showing up on just one of the AIS internet sites.
He does not show up in the searches on the other sites, only MarineTraffic.com. I tried the MMSI number also and nothing show up in the others. 
(He has the new Class B transponder 5w version not satellite.)

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After digging into how the land stations work , looks like they may give you a free AIS receiver if you are in the right local near the ocean if you agree to share the info.
Inserting way to get get coverage.

https://www.marinetraffic.com/en/p/apply-for-free-ais-receiver

 

 

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30 minutes ago, woodpecker said:

After digging into how the land stations work , looks like they may give you a free AIS receiver if you are in the right local near the ocean if you agree to share the info.
Inserting way to get get coverage.

Yup. Have one here at the cabin, #3473. They sent the receiver and a nice antenna for free. Plug it in to the wall, the internet, mount the antenna up high and done. Just a black box. Easy.

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1 hour ago, Mark Set said:

It looks like they also use USCG receivers as well. The one in my area picks up AIS signals from 200 miles out in the ocean, so it must be up on a tower I guess. 

Maybe those pings are from Class A satellite AIS?
200 miles seem a long way out to pick up 12 watt VHF signal?

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I saw this the other day, this is what i was thinking of. Ok so not 200 miles but this one maxed out at 110. Most max out at around 25, this one must be way up there. Also, the individual targets will tell you how they were received (ground station or or sat).

 

AIS Capture.JPG

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16 hours ago, penumbra said:

As memory serves, 3 companies have terrestrial networks of any size and they swap data between them.

They differentiate using not large commercial networks like ports etc who sell their data but tapping into enthusiasts for securing greater coastal coverage. Antenna height, urban interference etc governs how much coverage they have.

26 minutes ago, woodpecker said:

Maybe those pings are from Class A satellite AIS? 200 miles seem a long way out to pick up 12 watt VHF signal?

No such thing. All AIS sats pick up all classes and where higher power normally produces greater update interval. AIS uses VHF band nothing to do with VHF radios.

Sailboat mast mounted dual VHF/AIS antenna can helpful or not helpful for producing AIS TX signals to overhead satellite RX getting a full packet of uncorrupted data for each vessel. This depends on sea state, boat heel etc and using antennas designed for the horizontal at different gains. Sat paths come more into play. 

Data clogging an issue in high traffic areas so Class B might get turfed by sat to give Class A priority.

Lots of issues for determining whether a vessel appears or not.

IMG_20201120_173128.jpg.d2bc6af293b63295d7cef6a11ffd2a71.jpgIMG_20201120_185536.jpg.a5c3619fdf73d9d61aa4c328c7ce8baa.jpg

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33 minutes ago, Mark Set said:

I saw this the other day, this is what i was thinking of. Ok so not 200 miles but this one maxed out at 110. Most max out at around 25, this one must be way up there. Also, the individual targets will tell you how they were received (ground station or or sat).

This was discussed at length in some previous thread. My station regularly receives AIS packets from over 700 nm away. And even that seems to be limited only by software clipping at 15 degrees in latitude and longitude...or something? Just now tracking a vessel way down the Baja. The trick is antenna altitude and the repetitive nature of the signal....some small percentage manage to get thru.

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3 hours ago, El Boracho said:

This was discussed at length in some previous thread. My station regularly receives AIS packets from over 700 nm away. And even that seems to be limited only by software clipping at 15 degrees in latitude and longitude...or something? Just now tracking a vessel way down the Baja. The trick is antenna altitude and the repetitive nature of the signal....some small percentage manage to get thru.

The marine layer over Calif is a nealy permanent inversion. A tropospheric duct.

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To add another complication to the range question, some places (e.g. Galapagos Islands) also put in AIS repeaters. We were surprised as we approached the Galapagos to start seeing targets at 100km range around the islands. They put the repeaters in so they can track all vessels within the Marine Reserve (AIS is required).

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Some of the shore stations are also local hams who brew up a a station out of old odds & ends.  One more blinking light to have going in the radio shack.  Service depends on their personal interest and amount of spare time.  

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5 hours ago, jack_sparrow said:

 

No such thing. All AIS sats pick up all classes and where higher power normally produces greater update interval. AIS uses VHF band nothing to do with VHF radios.

 

 

Ok, So if I paid extra to get the Satellite tracking info on Marine Traffic.com, the Class B receivers should show if they are beyond the base stations?

Right now on the free version it only show commercial Class A tracked by that are tracked by satellite.

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5 hours ago, woodpecker said:

Ok, So if I paid extra to get the Satellite tracking info on Marine Traffic.com, the Class B receivers should show if they are beyond the base stations?

Yes subject to TX/RX Sat constraints for Class B which is what I said and listed some.

5 hours ago, woodpecker said:

Right now on the free version it only show commercial Class A tracked by that are tracked by satellite.

Ditto and if no Class B showing at all, they are turned off, again which is what I said  or not available for free.

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OK, so why the need for setting up all the ground stations if that same info is available from satellites? 

On 11/23/2020 at 11:10 PM, jack_sparrow said:

Yes subject to TX/RX Sat constraints for Class B which is what I said and listed some.

Ditto and if no Class B showing at all, they are turned off, again which is what I said  or not available for free.

OK, so why the need for setting up all the ground stations if that same info is available from satellites? 

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Probably because it costs a lot more to put satellites in orbit and they charge for that service.  Suspect the nearly always available satellite info is more for commercial customers and the land-based receivers/web transmitters are geared toward general public/media, etc.  The fee based services pay for all the necessary infrastructure (staff, servers, overhead, etc.) to publish the data to the web.  And hopefully some profit to make all the investments worthwhile.  Pretty sure there is no mandate to make the information readily available on the internet, just that the transmitters/receivers talk to each other out on the water.  Private companies stepped in to provide the service, but they don't do it just for our enjoyment.

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3 hours ago, woodpecker said:

OK, so why the need for setting up all the ground stations if that same info is available from satellites? 

"..why the need for setting up all the ground  stations.." 

You are struggling.

AIS is 'vessel to vessel' and exists courtesy of international maritime regs.

Any other application of AIS is unregulated except use of the spectrum according to local regulations or international communication treaty. Hence a service with no expectations, you get what you are given. 

AIS is not exclusively Sat because; 

Sat spectrum capacity is finite an issue as noted.

On 11/24/2020 at 2:54 AM, jack_sparrow said:

Data clogging an issue in high traffic areas so Class B might get turfed by sat to give Class A priority.

Then the constraints of sat an issue as noted.

On 11/24/2020 at 2:54 AM, jack_sparrow said:

Lots  of issues for determining whether a vessel appears or not.

Finally amortised cost per transmission of sat to put it online is many, many times more than via a terrestrial signal. Users of sat are predominantly shipping companies, freight logistics, law enforcement etc. Hence AIS providers charge for general public access to sat or it's a lite service only.

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