Active Buoys 3 grams Why?
 

Just like the title - Why? :hmm:
Is it to balance/penalize between using passive vs active buoys?

I think it has to do with the increase of data recived from the buoy. Think of each GRAM as a segment of you platform's Buoy CPU. In Onmi mode it only has to deal with one hydrophone, in directional it has to deal with all, and in Active it has to deal with all the hydrophones plus the active processing subroutines.

But all the directional data has to be digitized anyway. Ambient sound is ambient sound it gets proccesed whether active or passive.

Exactly, you are not just swtiching modes you are adding features too you're current modes. With active the current modes vanish from the GRAMs and are replaced with "Supporting CH:_" but I imagian their subroutines are still in use plus what ever subroutines are being used to process the active returns.

I figured it was probably a game balance issue. Instead of using lines of active buoys to 'drive' contacts, they designed the game so that you can only effectively use 1 (maybe 2) active bouys at a time, giving MP opponents more opportunity to evade effectively.

To my knowledge the use of the GRAMs is just like in real life.

1 GRAM : Omni-directional data (just frequencies)
2 GRAMs : Frequencies & Bearing#
3 GRAMs : Frequencies (ok you don't see them but they are there), Bearing and Distance.

I read a more detailed explanation some time ago, basically it has to do with processing stuff and the available processing power and channels. You have to use more channels to use the active mode of a DICASS then just using its Omni-Directional mode.