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SO I'm in a corp with a bunch of miners, and we've just been war decced by a one-man corp. Most of our skills are focused on the industry and mining side of things, with not a lot of attention paid to the combat side. Since we're all a bunch of rather low-sp players, my first thought was to use ECM to give us an advantage, but I'm having a little trouble understanding how it works. I get that it's based on chance, based on your ECM strength and the sensor strength of your target, but does it stack? Meaning, do our chances of locking a guy out improve if we can get multiple people to jam a target with multiple racial jammers or multispec?

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You have two questions here: How does ECM work and the question about a low-SP fleet. I'd separate those into two different questions. And it's hard to formulate a good answer to the fleet question without knowing what kind of ships the enemy brings. – Mad Scientist Nov 21 '12 at 11:17
TBH, we don't know what they're bringing either, but that's not my biggest concern here. My main concern is whether or not ECM is more effective if you've got numerous pilots firing jammers, rather than just a few. – cornjuliox Nov 21 '12 at 11:31
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The first important point to think about when bringing ECM is how you will prevent the enemy from killing your ECM. ECM ships have low tank and can take out multiple enemy ships, they are almost always the first ships to be called primary. You have two options to keep your ECM alive:

  • Keep them out of range of the enemy, a Blackbird can jam at 100km
  • Bring enough ECM to jam all enemy ships most of the time

The chance to jam with one jammer is jam strength/sensor strength, so if your jam strength is higher than the enemy sensor strength you will effectively perma-jam the enemy. If it is lower, you will only have a certain percentage chance to jam. Examples:

  • A Blackbird with jam strength of 8 with racial jammers (depends on fitting and skills) against
    • A Rifter with 8: 100% jam chance
    • A Hurricane with 16: 50% jam chance

If you have a below-100% chance to jam, you can use multiple modules (on the same ship or on other ECM ships) to increase the chance to jam. The chance to jam follows the following formula for multiple jammers:

jam chance = 1 - (1 - jam strength / sensor strength)^n

So if you try to jam the hurricane with 2 jammers you get a 75% chance of at least one jam succeding, and 88% chance for 3 jammers.

You can also overheat your jammers to increase the chance to jam for a short time if you have the thermodynamics skill. You should also pretty much always use racial jammers, they are far better than multispectrals. You need to either guess which ships the enemy brings or get some intel before the fight to chose the appropriate jammers.

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Or to put it a simpler way : each Jam is a dice roll. The more jammers you target at a ship, the more dice rolls you get. Each dice roll doesn't affect other dice rolls, but unless you can get the jam strength more then the other ships sensor strength, there is still a chance that all the dice rolls will come up bad in a row. If you can get your jam strength above the other ships sensor strength, then it's like trying to roll 1 to 6 on a six sided dice. It will always happen. – camster342 Nov 22 '12 at 5:02
I am apparently wrong. Would you please edit your answer so that I can remove that -1 from it? I did not do my research properly. – Phill.Zitt Dec 12 '12 at 16:41

Mad Scientist is providing you with some out of date information

ECM modules do NOT stack. The chance of a jam succeeding on a particular cycle is independent of any other ECM modules you have. There are some modules that will increase the strength of your ECM modules, but the modules that actually DO the jamming are independent of each other. So although each module will have the same chance to jam as the next one based on your skills, the more modules you have, the more chances you have.

Also, although I don't know the exact formula, I do know that you are never GUARANTEED to jam someone, regardless of yours or their respective sensor strengths. Sensor strengths will affect your chances of jamming, but it's no longer based solely on ship sensor strengths. It used to be, so it used to be the way that Mad Scientist states, but it's no longer that way. You can have a jam strength of 10 against a ship with a jam strength of 5, and it is possible for you to still miss a jam cycle. You will most likely perma-jam them, but it IS possible to miss a cycle.

Racial jammers are best if you know what you're going up against, but don't hesitate to activate the module for the wrong race anyway. Although the sensor strength is lower, there is still a chance to jam them. I have jammed several ships using off race modules. You certainly have a lower chance of succeeding, but it's still very do-able. I have a rainbow set up on my Griffin (one of each race), and my Falcon has 2 of each, except Amarr, which only has one (only 7 mids on the Falcon).

As to the tank of an ECM ship - it's tank is ECM. If you jam the hostile, your tank is working. If you can't jam the hostile, your tank is not working. Simple as that.

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That I think is what Mad Scientist is trying to say, but is hiding it behind a statistical math formula. – camster342 Nov 22 '12 at 4:54
Do you have some source that the jam is never guaranteed? I'm pretty certain that a jam is at 100% chance when the jam strength exceeds sensor strength (as long as you are inside optimal range). – Mad Scientist Nov 22 '12 at 16:35
Side note: most of the mission NPCs have an nearly infinite jam strength, and so they have an almost guaranteed 100% chance to jam you. If you want to verify the "guaranteed jam" fact in PVP, you should try it on the Buckingham test server. My account wasn't reactivated during last Buckingham accounts patch, so i can't login for testing purpose at this time. You'll have to do it yourself =P – Lysarion Nov 23 '12 at 13:55
Is the jam chance equation correct at least? Are they still using that? – cornjuliox Nov 24 '12 at 16:11
My evidence is all anecdotal from actually using the ECM in the not too distant past against a multitude of different ships, as well as reading the Eve Online forums and other websites while trying to learn about it. A lot of people are upset that there is no way to know for certain if you're going to get a jam on someone. It used to be the way you say Mad Scientist in that you could just get your strength above the target, but a lot of people complained because they don't like being jammed, so it was changed. – user37459 Nov 25 '12 at 20:12

The simplest answer is that ECM from multiple pilots does not stack.

As to the overall problem, it's regularly stated that a lot of poor quality pilots often have a chance against a single skilled pilot, but that is really another question you should ask and a rather broad one at that.

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