To follow up on
Wad's explanation of advanced sensors:
From the original MW4 Vengeance reference manual:
QUOTE
Advanced Sensors
Some BattleMechs are capable of mounting advanced sensors that offer additional capabilities. These include the Beagle Active Probe (BAP) and the Guardian ECM. The BAP increases the active sensor range and decreases missile lock time. The drawback is that is also decreases enemy lock-on time because it emits such a strong signal.
Conversely, the Guardian ECM is essentially a defensive weapon because it provides your BattleMech with a Stealth mode by decreasing the range in which your BattleMech is detectable. Guardian ECM also reduces the effectiveness of a NARC beacon if one hits you. Unfortunately, just as with the Beagle Active Probe, the Guardian ECM emits a strong signal and makes missile-lock for enemy units easier. If your BattleMech has both a BAP and a Guardian missile, lock-on time is reduced. However, even though you have Guardian ECM, you can also give yourself away if you fire up your Jump Jets or your heat level is above the 50 percent mark on the heat scale. Therefore, you should use these advanced sensors wisely and sparingly.
TRM4 says this about the electronics:
QUOTE
ECM: Electronic Countermeasures reduces enemy radar detection range. Extremely valuable for scouts, snipers and insurgency units. Units with passive sensors engaged will not see ECM equipped units on their radar, and will not be able to lock on or access damage. Extremely useful for approaching enemy emplacements undetected. While it can render units more difficult to detect, it reduces the time required for an enemy to obtain missile lock-on. While it's benefits may not be immediately obvious when piloting an equipped mech, it's effect is clear to see when facing ECM equipped enemy units.
QUOTE
BAP: Beagle Active Probe increases radar range from 1000 meters to 1200. Units equipped with BAP will be able to detect shutdown enemy units, although only within 100 meters. Like the ECM, it reduces enemy lock on time by 30% and should be used with caution in missile heavy environments. Extremely useful for scouting or missile equipped mechs. It can sometimes be useful for sniper operations by allowing units equipped with long range weapons to engage stationary targets well beyond visual range.
From
Grendel's Newbie Tips and Tricks Guide:
QUOTE
ECM
Cuts down the range at which enemy sensors can see you. Standard sensors see ECM at 500 m, BAP sees ECM at 800 m. DECREASES enemy LRM lockon time when they're trying to kill you. VERY useful on pretty much any mech. Keeps sniper/support mechs hard to find, and helps brawler/harassers sneak in.
BAP (Beagle Active Probe)
Increases sensor range vs standard mech from 1000 m to 1200 m. Decreases your lock time with your LRMs versus enemies, but also decreases lock time for enemies trying to kill you. Good for fire support mechs or scouts. Basic rule of thumb: LRMs take 3 seconds to lock on. Reduce by 30% if YOU have BAP, and reduce again by 30% for EACH of BAP and/or ECM on your target. ECM doesn't help you lock on, but it does hide you, so you might get a free shot on the poor, unaware sucker.... Note that none of this takes effect if you are passive, as your ECM and BAP turn off when your radar does.
While we're on the topic: You MUST have your radar ON to get a missile lock with ANY guided missile.
Truncheoneer's MW4Online Newbie Superguide offers this analysis:
QUOTE
ECM and BAP -
Two electronic devices are available: The ECM (Electronic Counter-Measures) and the BAP (Beagle Active Probe). A few Mechs can carry both, most can carry one or the other, and a few can carry neither. The following forum thread discusses them:
http://www.mw4online.com/forums/showthread...=&threadid=2191. Kyle Reece has posted a lot of very enlightening data. However, as you?ll see in the thread, there are still a few questions lingering about just how they work, especially in tandem. Note that even the game developers contradicted themselves in the manual and the MechLab.
More info on this, from Roadkill:
"ECM does not affect how soon an equipped Mech detects another Mech.
"BAP does not affect how soon an equipped Mech is detected by another Mech.
"Neither has any effect if your radar is off.
"IFF has no effect on radar detection at all.
- KD~Roadkill
The contradiction noted in the Superguide stems from the Mechlab description of ECM which reads:
QUOTE
Electronic Counter-Measures (ECM)
ECM is a defensive unit added to a 'Mech's sensor system. It decreases enemy sensor range and increases enemy missile lock-on time.
Electronics aside, on the subject of avoiding missiles that already have a lock, it's been my observation that missiles make their best course corrections early in their flight when they are still traveling relatively slowly. They don't adjust well at the end of their flight. Try to dodge perpendicularly to their angle of approach just before they are about to hit you. If you time it correctly a large number of missiles will just plain miss and a bunch more will do the crazy 180 course correction thing and if they hit you at all the damage won't be concentrated in one spot.
Not only did I get a lesson on knock vs. knock down (Thanks again Didy and Sliv 
)but I also got a lesson on what not to do when a missle boat locks on you. Is there anything you can do to break missle lock other than putting terrain between you and the incoming missles? I usually try to move to put a mech from the opposition in the path of the incoming but last nite there weren't enough of us. That Argus just wasn't cooperating by coming into brawling range. If you increase your velocity from side to side with respect to the missle launching mech will that increase your chances of breaking lock?
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