Satelite AIS.

[bcn]

Some countries are combining the data from the Sentinel family of satellites using SAR (Synthetic Aperture Radar) with resolutions of 10m with land, vessel and sat based AIS reception in order to identify targets/vessels that due to their size should have AIS but do not show any signal.
Illegal fishing or other fishy operations....

[barnakiel]

I think those of us here who are actually interested in this technology may want to go to the providers' pages now and read, read, read ...

It is wrong to assume AIS B works over the sat. It may, it may not.

It may also be a poor choice for tracking.

Also, look at how the satellites move (MOVE) and how this affects how the tracking is done.

Do not forget AIS A class ships may be equipped with DEDICATED sat trackers.

Class B owners may build a similar, but not equivalent, rig at their own expense. Or buy from a Sat AIS provider.

And PLS stop mixing up tracking services like ...traffic.com with who actually provides the service. This is like believing my Firefox browser is an operating system.

b.

[bcn]

so, for reading:

https://www.km.kongsberg.com/ks/web/nokbg0397.nsf/AllWeb/1FF64AD3A50DEF03C1257FD50038DA44/$file/Datasheet_ASRx50.pdf?OpenElement

The end-to-end performance exceeds existing SAT-AIS receivers, where the superior sensitivity of the ASR x50 makes the receiver capable of detecting even AIS class B vessels.

in this context:
https://artes.esa.int/sat-ais/overview


Another white paper about SAT-AIS:
https://cdn2.hubspot.net/hubfs/18361...er_Final-1.pdf

[El Pinguino]

Good stuff...
So not all class B AIS is created equal...
'Class B SO: Shipborne AIS transceiver (transmits and receives) which operates using SOTDMA. Class B SO must have an integrated display, transmit at 5 W or 1W, and provide the capability to interface with multiple ship systems. Class B SO units report every 2 seconds to 3 minutes depending on the speed and rate of turn of the vessel Beginning in January 2013, all new installations of Class B SO devices will be required to transmit a position report for satellite detection on two new channels reserved exclusively for detection from space.'

[ranger58sb]

Originally Posted by El Pinguino

No probs Ben

The third one is a US flag boat , Lady Arisha, doing an east bound passage to Panama or wherever....

Ping, what is it about the "trial" version that lets you see those?

Without the trial... I can see "ships" in those areas, including Class B transmitters... but I don't see (or recognize?) those specific three...

And I can only see tracks for those identities the system has already resolved. Many or simply labeled "Pleasure Craft" and "Position received via satellite." Can't see tracks for those, but I can't tell why the system hasn't resolved the names and so forth. For those, I just get a "Status unknown."

OTOH, when transmitters are named, I can see the track.

So what does "full access" mean in your trial. The only addition I see mentioned is the ability to track more than one ship at a time...


Maybe because my instance of MT is a snapshot that started at Time X (effective when I started it)... without historical (older than Time Y something) ship locations on it?


Or... ??


Edit: Ah. Think I found it. I only have access to the last three days worth of track info...

-Chris

[El Pinguino]

Chris, I could just see unnamed 'sat ' ones... no details, no track. ... before signing up for the free trial.

Now I get the works...almost.

Interesting that even the 'empty bits' of ocean are so busy ( this pic is filtered for just dry cargo ships) .... so much for 'I never stand a watch cos I never see any ships'.

This is just too much fun, I really should be doing boat jobs.. oh well, as they say, never put off til tomorrow what you can put off indefinitely...

[ullar]

Originally Posted by El Pinguino

Interesting that even the 'empty bits' of ocean are so busy ( this pic is filtered for just dry cargo ships) .... so much for 'I never stand a watch cos I never see any ships'.

Well, taking into account the vastness of the ocean, it's still empty. What's the probability of getting on of those ships within a mile from you? Or within few hundred yards? Near to non.

[El Pinguino]

Ping's First Law of Probability says the odds are very good.

[barnakiel]

This is also worth reading for someone seriously interested in class B to be used in via sat tracking:

Home - ABSEA AIS

Apparently some existing class B transceivers may count on software upgrade to make them better sat track'able.

I am not into this technology but I think those of us who are may now try to check which ones they are, and which sat company is about to implement this tweak.

Cheers,
b.

[Snowpetrel]

Originally Posted by bcn

Some countries are combining the data from the Sentinel family of satellites using SAR (Synthetic Aperture Radar) with resolutions of 10m with land, vessel and sat based AIS reception in order to identify targets/vessels that due to their size should have AIS but do not show any signal.
Illegal fishing or other fishy operations....

Very interesting. Using SAR as well. I wonder how it goes tracking a yacht?

[Snowpetrel]

Originally Posted by barnakiel

I think those of us here who are actually interested in this technology may want to go to the providers' pages now and read, read, read ...

It is wrong to assume AIS B works over the sat. It may, it may not.

It may also be a poor choice for tracking.

Also, look at how the satellites move (MOVE) and how this affects how the tracking is done.

Do not forget AIS A class ships may be equipped with DEDICATED sat trackers.

Class B owners may build a similar, but not equivalent, rig at their own expense. Or buy from a Sat AIS provider.

And PLS stop mixing up tracking services like ...traffic.com with who actually provides the service. This is like believing my Firefox browser is an operating system.

b.

Though the truth is that it seems to work reasonably well with a standard class b ais system, at least in the less crowded south pacific.

It is not as good as a proper sat tracker, but its cheaper. Free even for a one off short offshore passage if you are happy to use the free trial.

Marine traffic may only be a data handling company. I dont know if they have their own tracking assets and unique storage of past tracks, or if they just repackage others data. Regardless they do a pretty good job of it, and the sat data certainly isnt freely availible to anyone, as far as I know, so I assume they buy the rights to the data and try to onsell access to the public.

Maybe you have a link to a some other source of the sat data at a reasonable monthly price?

One note is that marine traffic's accounts only allow real time sat tracking of a limited number of targets. The $20/month one allows access to one vessel. The $450 plan gives access to real time tracking of 15 vessels and the rest are deliberately delayed by 12 hours.

Even their $800/month plan still has 6 hrs delay for all except 50 tracked vessels.

[hoppy]

Marinetraffic looks like they have their own network of land based receivers. So they will also do the track storage from their own stations and therefore probably store all S-AIS they receive.

Ship Spotting AIS Receiver - Set up AIS Receiver | AIS Marine Traffic

[barnakiel]

Originally Posted by hoppy

(...) So they will also do the track storage from their own stations and therefore probably store all S-AIS they receive.
(...)

Do not get hung up. If this is important for you, ask at source, avoid 'probablies'. If they store something, who and how can ask the data? How much time does it take, and what is the procedure?

If you do not know these answers, assume nothing. Assume they do NOT store, nor share.

And to (???) store (???) and to make available to SAR or other authorities are two different things. Never forget things that happened to others.

If you think the track may at any point be required for SAR or other operations, do not rely on services that may and may not co-op with other services.

Tracks can be sent directly to emails (e.g. a family member or a fellow sailor). These are immediately available should anything go off the rails.

Avoid uncertainty if you want to control / reduce or ascertain risk.

b.

[El Pinguino]

Marinetraffic was set up about 10 years ago by a Greek university. https://www.marinetraffic.com/blog/a...rce=newsletter
They have 3000 terrestrial stations both sponsored and voluntary. I can only assume that they have to buy the sat info from the satellite operators. I'm sure government agencies have an arrangement with the sat operators as well.
All the info they have is public domain and you can get what you pay for without having to ask.
The stats for what they receive and store are in that link.

Its not like someone's cellphone or Iridium records ... they are considered private and as we have seen in the past can be quite difficult to access.

[hoppy]

Originally Posted by barnakiel

Do not get hung up. If this is important for you, ask at source, avoid 'probablies'. If they store something, who and how can ask the data? How much time does it take, and what is the procedure?

If you do not know these answers, assume nothing. Assume they do NOT store, nor share.

And to (???) store (???) and to make available to SAR or other authorities are two different things. Never forget things that happened to others.

If you think the track may at any point be required for SAR or other operations, do not rely on services that may and may not co-op with other services.

Tracks can be sent directly to emails (e.g. a family member or a fellow sailor). These are immediately available should anything go off the rails.

Avoid uncertainty if you want to control / reduce or ascertain risk.

b.

I don't care about S-AIS for SAR for myself. I have a GPS EPIRB, PLB and I have included my YellowBrick tracking site and my current satphone number when I registered my EPIRB with AMSA


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