Eve Masterclass - ECM Modules And Math

"That Scorpion can permajam 5 ships!"

"I was permajammed and couldn't fight, nerf Falcons!"

"Multispecs are ok if you don't know what you are fighting."

After the post where I commented on a Rook pilot's poor setup an anonymous commenter said:

Using Multi's is not always a bad idea, especially if you do not know what you will be going into. I usually carry a racial of each type (sometiems 2 caldari) and fill the rest of my slots with racials, for added flexibility. But yeah... he was prolly a noob without full t2 fit.

I figured I should do a quick post on the intricacies of how ECM works and why I think Racial ECM mods are almost always better than Multispec ECM Mods.

First off, let's define everything so we are all on the same page.

ECM, aka Electronic Counter Measures, are a mid slot module you can place on any ship but only certain Caladri ships have a bonus to their performance which is why they are not used elsewhere by experience pilots. When fitted, a pilot can activate an ECM mod against a target and the module then has a chance to "jam" that target which in effect breaks all of its current target locks and prevents any more from being obtained for the duration of the jam which is 20 seconds. Multiple ECM can be targeted at a single ship.

There are five types of ECM modules: one for each of the sensor types of the four factions (Amarr = Radar, Minmatar = Ladar, Caldari = Gravimetric, Gallente = Magnetometric ) called Racial ECM mods, and one called Mutilspec because it has equal strength against all four sensor types. The Racials on the other hand are strong against their respective type and very weak against the other three.

The chance of an ECM module to jam is calculated as thus:

(Strength of ECM mod against target's sensor type) / (Target's Sensor Strength)

For example, a Thorax with a sensor strength of 15 is attacked by a Gallente Racial ECM mod with Magnetometric strength of 11.90577, a Caldari Racial ECM mod with a strength of 3.96859, and a Multispec ECM mod with a strength of 7.93718 all mounted on a Falcon. The odds of each one successfully jamming are:

Gallente Racial: 79.37%
Caldari Racial: 22.05%
Multispec: 44.10%

So one would think that having Multispec mods fitted would be the best option when you don't know what you are going to be jamming, right? Well, not exactly.

Let's look at three cases where a Falcon is trying to jam a Thorax with 6 ECM modules. First case where two Gallente Racials are used and four other racials, second case where six multispecs are used, and a third case where we have one Gallente Racial, three off-Racials, and 2 multis.

Case #1 - 2 On Racial, 4 Off Racial

ECM Strength	Target Sensor Strength	Chance of success
11.90577	15	79.37%
11.90577	15	79.37%
3.96859	15	26.46%
3.96859	15	26.46%
3.96859	15	26.46%
3.96859	15	26.46%
		98.76%

See the 98.76% at the bottom? That reflects the chance that at least one of the six modules will achieve a jam against the Thorax. It is calculated as thus:

1 - ((1- (chance of first jam working)) * (1-(chance of second jam working)) * (1-(chance of third jam working)) * ...

In other words, the chance of getting at least one jam is the inverse of the odds of all jams failing. Ok then? On to case number two.

Case #2 - Six Multispecs

ECM Strength	Target Sensor Strength	Chance of success
7.93718	15	52.91%
7.93718	15	52.91%
7.93718	15	52.91%
7.93718	15	52.91%
7.93718	15	52.91%
7.93718	15	52.91%
		98.91%

As you can see, the cumulative result is virtually identical. However, the multispec ECM module has 50km less range and uses 50% more capacitor. When you are a Falcon using range as a defence, being at 100 km from the action opposed to 150 km is a big deal.

Case #3 - 1 On racial, 3 Off racial, 2 Multispec

ECM Strength	Target Sensor Strength	Chance of success
11.90577	15	79.37%
3.96859	15	26.46%
3.96859	15	26.46%
3.96859	15	26.46%
7.93718	15	52.91%
7.93718	15	52.91%
		98.18%

Again, virtually the same amount of success as the previous two. So of our three cases, only case one with six racial ECMs gets the lower cap use and awesome range while still maintaining a decent jam percentage. But what about if I only have one On racial and 5 off racials?

Case #4 - 1 On Racial, 5

ECM Strength	Target Sensor Strength	Chance of success
11.90577	15	79.37%
3.96859	15	26.46%
3.96859	15	26.46%
3.96859	15	26.46%
3.96859	15	26.46%
3.96859	15	26.46%
		95.56%

Surprise! The cumulative effects are still such that the Thorax is jammed 95% of the time.

* * * * *

Now time to get exotic. What if we are trying to jam two enemy cruisers, one Thorax and one Moa with a sensor strength of Gravimetric 16? Assume we are going with either 6 Multispec or 6 Racials and not a combination, and also assume we have two On Racials for each one (as Gallente and Caldari are very popular, I tend to make sure I have two of those Racials loaded).

Case # 1 - 2 On Racials per ship, 1 Off Racial per ship.

ECM Strength	Target Sensor Strength	Chance of success
11.90577	15	79.37%
11.90577	15	79.37%
3.96859	15	26.46%
		96.87%
ECM Strength	Target Sensor Strength	Chance of success
11.90577	16	74.41%
11.90577	16	74.41%
3.96859	16	24.80%
		95.08%

As you can see, those cruisers are in trouble. BUT WAIT! What if they are two Thoraxes and you have to split your On racial ECM? Or you only have one Caldari and one Gallente ECM fitted for some reason?

Case #1b - 1 On Racial, 2 Off Racial per ship

ECM Strength	Target Sensor Strength	Chance of success
11.90577	15	79.37%
3.96859	15	26.46%
3.96859	15	26.46%
		88.84%
ECM Strength	Target Sensor Strength	Chance of success
11.90577	16	74.41%
3.96859	16	24.80%
3.96859	16	24.80%
		85.53%

As you can see, now we're in trouble! No wait, we're not in trouble. The odds of jamming each ship is still above 85%. That's still pretty good odds for jamming them a long time, long enough to reduce them to rubble.

Case #2 - 3 Multispecs per ship

ECM Strength	Target Sensor Strength	Chance of success
7.93718	15	52.91%
7.93718	15	52.91%
7.93718	15	52.91%
		89.56%
ECM Strength	Target Sensor Strength	Chance of success
7.93718	16	49.61%
7.93718	16	49.61%
7.93718	16	49.61%
		87.20%

Ah, not as strong as the 2 On Racial scenario, but slightly better than the 1 On racial each scenario. Not worth it for the loss of range and higher cap use, is it?

* * * * *
One last cruiser scenario. Three enemy cruisers, two Thoraxs and a Moa.

Case #1 - 1 On racial, 1 Off racial per ship.

ECM Strength	Target Sensor Strength	Chance of success
11.90577	15	79.37%
3.96859	15	26.46%
		84.83%
ECM Strength	Target Sensor Strength	Chance of success
11.90577	16	74.41%
3.96859	16	24.80%
		80.76%

Still sitting pretty at 84% per Thorax and 80% on the Moa (that one extra point of Sensor Strength on the Moa makes a big difference, eh?). And with Multispecs?

Case #2 - 2 Multispecs per ship

ECM Strength	Target Sensor Strength	Chance of success
7.93718	15	52.91%
7.93718	15	52.91%
		77.83%
ECM Strength	Target Sensor Strength	Chance of success
7.93718	16	49.61%
7.93718	16	49.61%
		74.61%

Now we are seeing serious degradation of the Multispec performance.

So we have seen that Racials perform in most scenarios almost as good or better than Multispec ECMs with the added bonus of 50% bonus to range and cap use. Against cruisers. What about ships with more sensor strength?

* * * * *

Battleships have high sensor strength. Like a Megathron for example with a strength of 21. What are the Chances of jamming it?

Case #1 - 2 On Racials, 4 Off Racials

ECM Strength	Target Sensor Strength	Chance of success
11.90577	21	56.69%
11.90577	21	56.69%
3.96859	21	18.90%
3.96859	21	18.90%
3.96859	21	18.90%
3.96859	21	18.90%
		91.89%

Still healthy at almost 92%. And Mutlispecs?
Case #2 - 6 Multispecs

ECM Strength	Target Sensor Strength	Chance of success
7.93718	21	37.80%
7.93718	21	37.80%
7.93718	21	37.80%
7.93718	21	37.80%
7.93718	21	37.80%
7.93718	21	37.80%
		94.21%

Just over 94%.

But wait! Another battleship warps in! Its a Raven!

Case #3 - 2 On racials, 1 Off Racial per ship

ECM Strength	Target Sensor Strength	Chance of success
11.90577	21	56.69%
11.90577	21	56.69%
3.96859	21	18.90%
		84.79%
11.90577	22	54.12%
11.90577	22	54.12%
3.96859	22	18.04%
		82.75%

Ah, what if we have a bad setup day?

Case #2b - 1 On Racial, 2 Off racials

ECM Strength	Target Sensor Strength	Chance of success
11.90577	21	56.69%
3.96859	21	18.90%
3.96859	21	18.90%
		71.52%
ECM Strength	Target Sensor Strength	Chance of success
11.90577	22	54.12%
3.96859	22	18.04%
3.96859	22	18.04%
		69.18%

And with Multispecs?

Case #4 - 3 Multispecs per ship

ECM Strength	Target Sensor Strength	Chance of success
7.93718	21	37.80%
7.93718	21	37.80%
7.93718	21	37.80%
		75.93%
ECM Strength	Target Sensor Strength	Chance of success
7.93718	22	36.08%
7.93718	22	36.08%
7.93718	22	36.08%
		73.88%

So here we can see Multispecs are starting to look more preferable in the case of multiple high sensor strength targets when off racial to your installed ECM mods, but the difference not very significant. For my money, I prefer the high range and better cap use of the Racial ECM mods.

Side Notes:
- Minmatar ships have the lowest Sensor Strengths, for example the Rupture is 12 compared to 15 for the Thorax, 16 for the Moa, and 14 for the Maller. For this reason, I always tend to double up on Gallente and Caldari ECM mods first.

- There are ECCM modules you can fit to your ship that will almost boost your sensor strength. For Cruisers, this means one of them will get you to battleship-like strengths and might make the difference between life and death against a jammer ship. Two can make a Falcon's life very difficult indeed. On battlecruisers and battleships, it can make them seem un-jammable. Only problem is that they take valuable mid slots on your ship so they tend to be overlooked.

- There are also Remote ECCM projectors so that a support ship can boost friendly ships' sensor strengths by up to 120% at a range of 25-50 kilometers. Again, valuable mid slots required.

- ECM Drones are like little flying Multispec jammers with low strength but are evidence of the power in numbers. The Wasp EC-300 is strength 1, Vespa EC-600 strength 1.5, and Wasp EC-600 is strength 2. Against a Thorax they have a chance to jam of 29%, 41%, and 51% respectively.

- See info about the Caldari jamming ships here.