Comar AIS Receiver and Splitter

[Paul Elliott]

Originally Posted by donradcliffe

AIS transponders are getting more popular by the week--I just passed English Harbor in Antigua, and picked up 36 transponders--all from yachts. If this trend continues, I can see where the commerical shipping would use a filter near ports--I just hope they remember to turn it off in the open sea.

Let me point out that there is no "ignore Class-B" filter.

Some hobbyist programs let you do this, but the AIS systems in use on ships do not ignore Class-B. They may filter out stopped and otherwise non-threatening targets, but that's about it. Some older systems will not decode the Class-B "static" information (vessel name, callsign, dimensions), but they all properly decode position/course/speed for Class-B vessels. Newer systems decode it all.

[richardhula]

Originally Posted by Paul Elliott

Let me point out that there is no "ignore Class-B" filter.

Some hobbyist programs let you do this, but the AIS systems in use on ships do not ignore Class-B. They may filter out stopped and otherwise non-threatening targets, but that's about it. Some older systems will not decode the Class-B "static" information (vessel name, callsign, dimensions), but they all properly decode position/course/speed for Class-B vessels. Newer systems decode it all.

Not quite true Paul. SeaPro PC chartplotter by Euronav (for one) does have a class B display filter, and it's certainly not a hobbyist program.

I also found that my early version single channel NASA AIS rx didn't receive any class B transmissions.