DocBach, on 11 February 2013 - 10:02 PM, said:
One caveat to that is the part in the rules saying to be affected by ECM you need to be within the operating radius, and it is not affected by LOS ie LOS that traces through the bubble does not provide ECM's affect against sensors. The second part makes me interpret the rule to read that you need to be inside the circle proper to have the full on sensor jamming effects; outside the bubble the Guardian can mask certain sensor scanning ability to determine chassis type, loadout, damage, ect, but only inside the bubble are locks actually compromised. This would also make it more in line with the descriptions of ECM from the Technical Readout 2750, where it was first introduced to the game:
GUARDIAN ECM SUITE
The Guardian ECM Suite is a broad-spectrum
jamming and electronic countermeasure device,
designed to reduce the efficiency of enemy longrange
scanning and surveillance equipment. The
Guardian interferes with sensor readings, preventing
identification at ranges of more than 180 meters.
Closer than that, 'Mech pilots usually rely on their own
vision in case their sensors cannot override the
Guardian's jamming.
Except, what the caveat about LOS actually says is:
"
To be affected, the spotting unit must be in the normal operating radius of the ECM/stealth system (note that stealth systems only affect the target unit and do not have a radius of effect, and so are only taken into consideration for the unit mounting that equipment). LOS does not affect this radius. If a spotting unit is within the range of multiple ECM systems, combine the effects of all the ECM systems."
(TacOps, pg. 224)
For comparison, what the basic rules in Total Warfare say (on pg. 134):
"An ECM suite has an effect radius of six hexes that creates a “bubble” around the carrying unit.
The ECM’s disruptive abilities affect all enemy units inside this bubble, as well as any line of sight traced through the bubble. It has no effect on units friendly to the unit carrying the ECM."
Also of note is the rules text for Angel ECM (TacOps, pg. 279):
"The Angel ECM Suite works like standard ECM (see p. 134, TW), but can also block the Bloodhound Active Probe, Artemis V and C3 Booster Systems, and even negates the locking systems of Streak missiles.
Streak missiles fired into or through a hostile Angel ECM bubble will not fire if the to-hit roll fails, but on a successful Streak launcher attack, the attacker must roll on the Cluster table as though the launcher were a standard (non-Streak) model."
The "LOS does not affect this radius" statement refers to how a unit within the ECM bubble may still be jammed regardless of whether LOS exists between the unit to be jammed and the ECM suite (e.g. one is still hammed if one is within the bubble but behind a building, hill, or other obstruction).
However, if the unit in question and the ECM carrier are facing each other on open terrain, any LOS actions by the unit (such as weapons fire or most sensor probes) that come into contact with the bubble (even if they go in one side and out the other to reach a target on the opposite side of the bubble, as explained in the ECM example in TW and noted by the "into or through" verbiage used in Angel's description) are still affected.
Additionally: even in "Standard Day" conditions on a clear and open field (so that there are no weather or environmental modifiers, from the Sensor Ranges Tables) and in the total absence of EW or stealth equipment (so that there are no modifiers from the ECM/Stealth Modifiers Table), 'Mech sensors can
still fail to pick up an opponent ~27.8% of the time (the combined likelihood of rolling a 9, 10, 11, or 12 based on
2D6 probabilities).
(Imagine the QQ that would result if the radar simply "didn't work" roughly one-third of the time, even in the absence of ECM!
)
For standard 'Mech Radar, introducing Guardian (and making no other changes) increases that likelihood of failure-to-detect to 91.6% (with an 8.4% chance of detection within 240 meters ('Mech Radar's "short" range, from the Sensor Ranges Tables)) and introducing Angel (and making no other changes) increases that likelihood to 97.2% (with a 2.8% chance of detection within 240 meters).
For Beagle, introducing Guardian (and making no other changes) increases that likelihood of failure-to-detect to 83.3% (with a 16.7% chance of detection within 360 meters (Beagle's "short" range, from the Sensor Ranges Tables)) and introducing Angel (and making no other changes) increases that likelihood to 91.6% (with an 8.4% chance of detection within 360 meters).
It would seem that, for MWO, the Devs took the TT system with those likelihoods in mind and (for now?
) simplified it so that , in TT terms, the Sensor Roll pretty much always fails.