(Answered) Hidden Units, and ECM

[grimlock1]

So far as I understand, if a hidden unit has active ECM, then an opposing unit either requires ECCM, or a higher level of probe to detect that hidden unit, aside from stumbling into them. 

But do opposing units detect the ECM of the hidden unit?  Would they realize, "Hey, somebody is jamming me, but I don't see anyone around."

[Xotl]

They know they're being jammed but not from where.

As a tactical note, once someone runs into the edge of the jamming field with two different units, they can probably make some educated guesses about where you are. 

[grimlock1]

They know they're being jammed but not from where.

As a tactical note, once someone runs into the edge of the jamming field with two different units, they can probably make some educated guesses about where you are.

That last part is what I was afraid of... 

So a hidden unit with Void Sig is basically the same as hidden unit with active Archangel?  The only way to pinpoint either is with Bloodhound, but anything with Battle Armor sensors or better could make some educated guesses about where the sneaky fellow is hiding.