Grismar's EVE Wiki : TargetJamming

Target Jamming (ECM)

ECM, when successful causes the target to lose all of their locks and in most cases be unable to re-lock for 20 seconds.

Methods of application:

• Modules - There are two types of modules. The more widely used modules are target jammers, which upon success cause a lost lock and an inability to lock anything for the duration of their cycle time (currently 20 seconds) The other modules are ECM Bursts, which in case of success cause everything in their area of effect to lose lock, but don't prevent the target from reacquiring the lock during the duration of the cycle. Also only one ECM burst may be active at the same time, meaning that fitting more than one is fairly pointless. The most important characteristics for modules are Cycle time, Jamming strength, Optimal Range and Falloff Range.
• Drones - ECM also comes in drone form. There are light, medium and heavy ECM drones. The difference is most notably their speed and their jamming strength. With the recent changes, drones are the most viable ECM method for non-specialized ships.

Working Mechanism:

Jamming is chance based. Every ship in eve has a characteristic known as sensor strength.

The chance to jam a target with one jammer is illustrated by the following formula:

C = J/S * 100%

Where J is the jamming strength of your jammer, S the sensor strength of the target ship and C the jamming chance in %. The chance to jam a target with multiple jammers is a simple deduction of Bernoulli's formula:

C = (1-(1-J/S)^n)*100%

Where J is the jamming strength of your jammer, S the sensor strength of the target ship, n the number of jammers and C the jamming chance in %. Computing the chance to jam with different jammers with different jamming strength against multiple targets is more for the realm of combinatorics enthusiasts, and is of little value here, so we shall not explore this further. Jammers also have an optimal and a falloff range, please refer to said article to calculate the falloff multiplier.

Note that multiplying the strength of the jammer by the falloff multiplier is incorrect, because the checking for falloff and the checking for jamming chance are two separate events - you must multiply the result from the chance calculation by the falloff multiplier to get an accurate answer.

Skills affecting:

• Electronic Warfare - 5% Reduction to capacitor need per skill level.
• Signal Dispersion - 5% bonus to strength of all ECM jammers per skill level.
• Long Distance Jamming - 10% bonus to optimal range per skill level.
• Frequency Modulation - 10% bonus to falloff per skill level.

Specialized ships:

ECM is the realm of the Caldari.

• Griffin - Frigate, gets 15% bonus to jammer strength and 10% bonus to jammer capacitor usage per level.
• Blackbird - Cruiser, gets 15% bonus to jammer strength and 10% bonus to jammer optimal range per level.
• Kitsune - Electronic Warfare Frigate, gets 20% bonus to jammer strength and 10% bonus to jammer capacitor usage per Caldari Frigate level. In addition, gains 10% to jammer optimal range per Electronic Attack Ship level.
• Scorpion - The only battleship in game truly dedicated to a form of EW, gets 15% bonus to jammer strength and 20% bonus to jammer optimal range per level.
• Rook - Non-cloaking recon, gets 10% reduction to jammer capacitor use and 30% bonus to ECM Target jammer strength per Recon Ship level.
• Falcon - Cloaking recon, gets 10% reduction to jammer capacitor use and 30% bonus to ECM Target jammer strength per Recon Ship level.

Counters:

There is a direct counter available - ECCM, which gives a percentage increase to a ship's sensor strength, making it hard to jam it. It is also possible to use more than one ECCM module at a time.

Examples:

A Scorpion with a pilot trained in level 5 Caldari Battleships, level 4 Signal Dispersion and running 5x T2 Multispectral Jammers on a Megathron translates to:

ECM base strength: 2.4
With bonuses applied: 2.4*1.75*1.2 = 5.04
Mega sensor strength: 21
Chance to Jam: (1-(1-5.04/21)^5)*100% = 74.64%