"Torpedo has acquired!"

Reading Clancy's SSN (one of his weaker books so far to be honest), and remembering movies and other books on the topic, I noticed this call-out and wonder what's behind it.
In DW we do not have this message, nor do we know if a fish acquired unless we check the weapons station or map screen for irregular movement of our fish ourselves.

So I wonder, how does it work in real life, how do sonar or weapon crews know? I'd imagine that a wire-guided ADCAP sure sends some info back to his host which may really say it has found a target or not.

Wouldn't it be, theoretically, possible in DW to alter the torpedo doctrine, having them "send a message" that they locked on to something?

I think that would be awesome!