Passive: passive electronic warfare occurs when we are listening to the broadcasts of the enemy.  We are not transmitting.  We are only listening: passive, quiet, stealthy, secretly hearing. 

Active: active electronic warfare occurs when we are broadcasting.  We are either guiding a missile toward an enemy or communicating electronically via radio, land-line (wires) or, now, using a light to communicate optically.  Active electronic warfare also occurs when we broadcast a signal to disrupt the enemies signals. 

Electronic Counter Measures: These are used to defeat (counter) the enemies attempts to use electronics to defeat our use of electronics.  Confusing?  Not on the battlefield!  The enemy attempts to communicate with various combat units.  If we can cause their communications to fail, while ours remain intact, we will destroy the enemy.  But what does the enemy do in an attempt to defeat our methods?  He uses Electronic Counter-counter Measures and so do we! 

For example: We have a missile we will launch and guide to the target using a pulse modulated signal at 50 gigahertz (active electronic warfare).  The enemy will beam a 50 gigahertz signal at our guidance radar in an attempt to disrupt our guidance system and thereby cause the missile to go astray (Electronic Counter Measures).  We know they will do that but we also know they can only beam one frequency toward our launched missile (intelligence work has discovered that).  So, we use a dual-frequency system that first beams a 50 gigahertz guidance signal then a 20 gigahertz guidance signal then a 50 again and a 20 again in very quick succession.  That is Electronic Counter-counter Measures.  It was exciting and fun. 

What can you do?  Enroll in the Telecommunications Degree program at Cameron University.  Learn electronics to such an extent that you will be able to quickly learn the more secretive concepts we use every day to protect our nation. 

Oddly enough, although I was trained in electronics I was sent for two tours of duty at Chu Lai, RVN.  After which I was assigned to the USS John King, a guided missile destroyer (that meant our mission was to destroy guided missiles that had been launched at the fleet we were protecting). 

For an example of passive Electronic Counter-counter Measures, in 1971 we borrowed some aluminum foil from the ships galley, cut it into strips and wadded up the strips.  We pushed them into the charge void on an 81 mm mortar and fired those packages into the air.  When the charge exploded in the sky the foil strips would unfurl and cause the enemies radar to bounce back at them whereby they could not see what was behind the foil mask.  Of course, the strips fell to the earth so we had to keep firing them to adequately protect an advancing or retreating fleet.  It was great.