It resets after the round, or at the very beginning (take your pick). ECM is totally overpowered, particularly when coupled with assaults.
I've been running a lance with a raven and 3 assaults loaded with Guass, PPC's and Missiles. Basically just find a wooded area and use breaching shot and multi target to wear the enemy down, reserve until last and the op for will barely get a shot in. In one mission I mowed down 3 successive heavy/assault (mixed) lances and took about 100 damage total. Just sat in the middle of a lake and let them come. If they ever get close enough to break ECM they are pretty easy to kill. Put a sensor lock pilot in the Raven and it's even easier.
For giggles I loaded up a Raven with a 50 dmg Large laser, a heap of armor and a +100m sensor pack and took on the Steel Beast Mission. Beat it easily, even though I did let that AC5 connect a couple of times and that was only because his cheating friends had 2 sensor lock pilots. (it took about 30 rounds LOL) just kept kiting him out.
I've been running a lance with a raven and 3 assaults loaded with Guass, PPC's and Missiles. Basically just find a wooded area and use breaching shot and multi target to wear the enemy down, reserve until last and the op for will barely get a shot in. In one mission I mowed down 3 successive heavy/assault (mixed) lances and took about 100 damage total. Just sat in the middle of a lake and let them come. If they ever get close enough to break ECM they are pretty easy to kill. Put a sensor lock pilot in the Raven and it's even easier.
For giggles I loaded up a Raven with a 50 dmg Large laser, a heap of armor and a +100m sensor pack and took on the Steel Beast Mission. Beat it easily, even though I did let that AC5 connect a couple of times and that was only because his cheating friends had 2 sensor lock pilots. (it took about 30 rounds LOL) just kept kiting him out.