How does this item work?

If i'm in combat with someone (that is, I know they're there) and then they go behind a barrier, drop their weapon, and turn it on, and they run out...

Do I get a free perception test to see them?
If I do perceive them, do I fire at them normally?
If I don't perceive them, do I fire at them normally?
If I do perceive them, is it a blind fire test?

Thanks!

No book handy, btu here's how I remember it:

You always get reactive perception tests.
If you see them you fire normally. If you just hear them, it's blind fire.

I don't know if the suit imposes it's own visibility penalties, but IIRC it does not.

I give free perception tests for ambush situations. Otherwise the foe must spend a Simple Action attempting to perceive. Note that there are modifiers to a perceptoin test based on how obvious the action is, among other things. If the guy in the chameleon suit takes off at a dead sprint he's got good odds of wasting his bonus. If he just slinks away, the opponent will have to figure out what's going on and use an action to try to locate his target.

Because the chameleon suit only penalizes vision based perception tests, it's possible that the pursuer will *hear* the suited character. In that case, the firing character is aiming based on sound but hasn't actually seen his quarry. I consider this blindfire and apply a -6 modifier. (Tangent - should a spatial recognizer offset some of this?)

If the suited character is seen (1 or more net hits on the perception vs. infiltration roll), then the firing character acts normally. Think of it like the blurry effect from "The Predator". Once you see where it is (and more importantly, process what you're seeing as an opponent) you may "apply the fundamentals of marksmanship."

I *would* apply a vision based penalty to an attack roll against a character who was using some kind of magic or other effect to blur his whole background. In that case, he's affecting the whole environment. I'd also consider a penalty if the suited character's appearance made it difficult for the shooter to pick up his gunsights against him (i.e. the suit and sights were similar colors). This isn't likely, however, because most SR characters use smartlinks and so target by illuminated crosshairs in their visual field.

Course if you got ultrasound tahts kinda ineffective