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Old 10-21-2011
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Originally Posted by JonEisberg View Post
Don't assume anything, Paulo...

In certain parts of the world, as more and more recreational vessels acquire AIS transmit capability, it may become commonplace for the Big Boys to filter us out as a "needless distraction", or of little more significance than a bug on their windshield... (grin)

A bit sobering, how loosely defined the current protocol re filtering of Class B transponders appears to be...

Panbo: The Marine Electronics Weblog: Class B AIS filtering, the word from Dr. Norris

I agree with you and had already saw that article, anyway:

In inclement weather in such waters it would generally be the correct practice to switch off the AIS Class B filter, considerably improving the probability of identifying small craft in poor visibility and bad radar clutter conditions. In general, there would be fewer Class B targets in such conditions. These would naturally wish to keep a greater distance from ships and, in any case, any detrimental over-alarming of the ships system would, in these conditions, be compensated by the benefits of increased probability of target detection. Of course, in other than crowded waters in good visibility, the AIS Class B filter should generally be switched off.

And at least offshore (out of straits) you should not have a problem with detection because there is no traffic that justifies the filter to be on.

Anyway i have heard that they are studding a common protocol regarding filtering. Any news about that?


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