ECM Suite
From BattleTechWiki
An Electronic Countermeasure (or ECM) suite covers the area around the unit on which it is employed, disrupting sensors and communications. One example is the Guardian.
[edit] Game usage
In MechWarrior IV: Mercenaries, the ECM is a selectable component for certain 'Mechs. It increases missile lock time for enemies and reduces the range at which the 'Mech can be detected.
In MechCommander 2, the ECM is also a component for certain 'Mechs. It makes the 'Mech in question undetectable by sensors. It appears to have no effect on missiles, due to the way in which the game handles weapons fire.
