Jamming Explained


In this post I intend to convey complete understanding of the effects of jamming on missiles in Escape Velocity: Override. Feel free to skip down to the summary at the bottom where you will find all the information here concisely and (hopefully) clearly presented. The combined jamming section now contains a simpler, though equally accurate, method of calculating results than it previously did.

The Basics A missile can be either invulnerable or 50%, 100%, or 150% vulnerable to any given type of jamming.
A jammer can provide either no, weak, strong, or both weak and strong jamming to any given type of jamming.
Jamming is only applied if it is of a type to which a missile is vulnerable.

Missile Behavior Ignoring system interference and asteroids, missiles will behave in one of 5 ways depending on how much they are jammed:

  • Home in on their target, all hitting.

  • Chase their target, most hitting.

  • Spread out in a triangle, most missing their target.

  • Turn slightly aside, all missing the target.

  • Veer sharply away, flying in the direction opposite the target's motion.

I hereby define the word "Jammedness" to mean, "The amount a missile is jammed, as measured in terms of the above list."

The Rules If the target is stationary, all missiles fired straight at it behave as #1. If the target is moving, then the following rules apply:

The target ship's jamming is the union of the types of jamming provided by its jammers, meaning duplicate jamming of the same type and strength is not cumulative.

Missiles are jammed by any type of jamming to which they are vulnerable, with their jammedness being a function of the union of the types of jamming to which they are vulnerable and the target ship's jamming.

The jammedness of missiles is cumulative, meaning a missile vulnerable to more than one type of jamming will be jammed more strongly if more than one of those types of jamming is present on the target ship.

Facts Rather than make a large chart covering every possible combination of missile vulnerability and jammer effectiveness, I have made a small chart and a set of rules that cover every situation. Here is a chart of what I call the "Jam Function", j(Jamming, Vulnerability), showing the behavior of missiles with different amounts of vulnerability to a given type of jamming when confronted by different strengths of that type of jamming:

                  Weak Jamming        Strong Jamming      
  50% Vulnerability  #2                  #3
100% Vulnerability  #3                  #5

That chart, together with the rules for combined jamming I will now talk about, allows us to predict how any imaginable missile will behave when confronted with any possible combination of jamming.

Combined Jamming Here are the rules I have derived:

#1 and #x = #x
#5 and #x = #5
#2 and #2 = #3
#2 and #3 = #4
#2 and #4 = #4
#3 and #3 = #4
#3 and #4 = #4
#4 and #4 = #4

In words,

  • No jammedness and any jammedness jams the missile in the amount of the jammedness.

  • Complete jammedness and any jammedness jams the missile completely.

  • Poor jammedness of two types jams the missile a medium amount.

  • Any other combination of jammednesses jams the missile greatly.

For calculations, I choose to interpret that data as multiplication with the following numerical values for the behaviors:

#1 = 1
#2 = 0.5 (one half)
#3 = 0.25 (one quarter)
#4 = (0, 0.25) (any other possible result)
#5 = 0

Now the standard rules of arithmetic apply.

Examples A hypothetical missile with the following jam vulnerabilities:
50% Type I
100% Type I

When fired at a ship with the following jamming:
Weak Type I

Will behave in the following way:
j(Weak Type I, 50% Type I) = #2 (as per the chart)
j(Weak Type I, 100% Type I) = #3
#2 and #3 = 0.5 * 0.25 = 0.125 = #4

Meaning it will swerve away from its target, missing.

Another hypothetical missile with the following jam vulnerabilities:
50% Type I
50% Type II
100% Type III

When fired at a ship with the following jamming:
Strong Type II
Strong Type III

Will behave in the following way:
j(No Type I, 50% Type I) = #1
j(Strong Type II, 50% Type II) = #3
j(Strong Type III, 100% Type III) = #5
#1 and #3 and #5 = 1 * 0.25 * 0 = 0 = #5

Meaning it will fly away from its target, in the direction opposite the target's motion.

Summary To predict how a missile will behave, use the following rules and refer to the list in the "Missile Behavior" section.
Information gathering:

  • A jam vulnerability is only checked against its own type of jamming.

  • Redundant jammers (duplicates identical in both strength and type) are ignored, with only the first one applying.

  • All strengths of a jamming type that are present on the target ship are checked against all vulnerability levels to that jamming type on incident missiles.

Evaluating data:

  • No jamming + any, all, or no vulnerability = #1

  • No vulnerability + any, all, or no jamming = #1

  • Weak jamming + 50% vulnerability = #2

  • Weak jamming + 100% vulnerability = #3

  • Strong jamming + 50% vulnerability = #3

  • Strong jamming + 100% vulnerability = #5

Simple rules:

  • Anything with #5 in it is always #5.

  • If there is anything other than #1 involved, the #1 can be ignored.

  • #2 * #2 = #3.

  • Any combination not covered by the above three lines is always #4.

I hope I have been able to shed some light on missile jamming in EV Override. I have done no research on system-based interference, asteroids, or other means by which a missile may lose its lock on its target, so if you have knowledge of such, please feel invited to post about it here.

This post has been edited by Qaanol : 10 June 2005 - 03:13 PM

Wow, that's very in-depth.

That should probably be kept as a permenant reference clip on the developers board or something. It's a good reference because jamming can be very annoyingly complicated in Override planning (especially when you're using ResEdit flags).

Well done pal.


So you got jamming explained! You got it explained to yourself, when you said you didnt know its meaning. And you have explained to it to us- and me. Because I said Veritarius Dartarion seems knowledgeable, when he knew something about seekers. Now I know how jamming works- why Needle Missile sometimes fly in circles around me but not hit. Seems extremely complex, so I will only comment generally like this.

pistgavin: Only annoyingly complicated with ResEdit flags? I didnt know it worked, Qaanol neither. I thought 64 meant how effective the jammer was, like in Nova. Nowhere was it mentioned 64 was hexadecimal. ResEdit makes it almost impossible to figure out. It is laid out so unintuitively that you simply cant know with ResEdit templates, and its not in the Bible either. With ResEdit, you can only know the way Qaanol did it.

This post has been edited by General Cade Smart : 12 June 2005 - 10:01 AM

hah I usually just used programs like MissionComputer that let you just tick a box 'weak jamming III' and so on. Must easier than numbers.