What exactly is a passive sensor ?

[chrisol]

I wouldnt say I'm anything other than a gamer, but it's going to depend a bit on the platform you are on and the type of unit you are trying to get a fix on.

I guess passive sonar on a sub would be the most typical example, in which case I would suggest:

Actions to maximise you passive sonar capabilities:
1. Slow down (to reduce your own noise)
2. Get in the right depth to detect your target (eg just above layer to allow your trailing sonar to detect below, or (? I'm guessing a little) higher to detect a surface contact
3. Change your course so you are not blocking your own sonar - towed sonar won't detect well directly in front of your sub (as your sub is in the way)

Actions to give you more useful information:
1. Moving at right angles to where the target is should ultimately give you better information regarding how far way it is (as the angle to the passive contact will change with your movement and give you a fix) - though as you've just slowed down this might take a little while
2. Do something to make it reveal itself... Try firing a torpedo down the angle you have for example - a boat trying to put distance between it and a torpedo tends to make a lot of noise ! (though this rather unfortunately also gives the enemy a lot if information about you)

These can be translated to some extent to other platforms (though hard to move a fixed land radar!)

Hope this helps, but I suspect someone who knows what they are talking about might be more useful...

Bw
Chris

[Blu3wolf]

ORIGINAL: nukkxx

OK very clear, thank you.

but be careful using it much, because almost every ship, plane, etc. has passive sensors, and that means always the other guy will see you before you see them

Aren't we talking milliseconds here ?

not quite the reason... its not time, but distance.

if your target is say 160 miles away and you are searching with an air radar mode like RWS with a modern radar, you probably won't see him.

he most likely will see you, not as accurate as a radar contact, and with no range information, but he knows *something* is there.

you have no idea yet. passive sensors are very useful. the mk 1 eyeball is passive, any heater (AAM) is passive, RWR systems are passive... any time you are emitting, you are letting a passive sensor see you very easily. if you are beyond the range at which you can *see* your target with that sensor, the passive systems will still happily see you. ELINT works on this principle.