This is for SR4. According to the rules (Arsenal pgs 105 and 135 and SR4A pg 329) an ECM system functions just like an area jammer. Which means it has a maximum range of 50 meters at rating 10 and a fall off of -1 rating/5 meters. I suppose that is alright if you are dealing with jamming in a building. Maybe. It is completely useless if you are dealing with vehicles (the things ECM is supposed to fitted on). You won't be using sensor aided targeting very often at <50 meter ranges (drones, sure but this is basically pistol to SMG range which means people on foot and no ECM) and the ECM provides no benefit beyond that range. Vehicle combat doesn't realistically happen at such short ranges nor do things like evading ground based radar systems when running borders, etc. Never mind the fact that sensor 6 + ECCM 5 program makes even ECM 10 useless.

For extra stupid, I notice things like the YNT Shibanokuji-Class Aircraft Carrier from WAR! comes with ECM 6, which has a range of 30 meters, or put another way, a range of less than the size of the ship by an order of magnitude (assuming at least a 300 meter length). What use is a sensor jammer that doesn't extend beyond the vehicle it is attached to? You can only defend the mast of the carrier and the flight deck is just SOL?

So how was this system supposed to work? Or better yet, does someone have some nice, simple house rules to fix this sort of idiocy?

The ECM system is possibly a little silly, the way it's written, but first of all, though I'm not an expert on firearms by any stretch of the imagination, 50m is not typical pistol range. 50m IRL is rifle range IMO.

The handcarried jammer works well enough RAW. I do, however, agree that it's potentially a silly with regards to the range, when we talk about vehicle combat distances. My suggestion for a simple quick fix would be to count vehicle mounted ECM systems as having an effective range as if they had a Signal of half the Rating. As per SR4A p. 222, that would mean that a Rating 10 ECM system would have an effective range equal to Signal 5 = 4km radius. That's still a little silly for a large ship like the one you mention, perhaps, but if we're into that size vehicles, you might simply considder its Rating 6 = Signal 6 = 10km radius, which is compared with i.e. Cell-phone towers, which probably wouldn't be too far off what a ship like that might be equipped with something equivalent to. I'm not sure it would be believable for a Rating 9 ECM system on a ship, as it would mean that the jamming field would have a 400km radius. That might be within effective ship-to-ship combat distance (for cruise missiles), but IMO it's possibly overdoing it, though I'm no expert on RW jamming and effective distances of such equipment.

Sorry, my point on saying pistol range was that 50 meters or less was within pistol range, which is not a typical weapon for a vehicle. No one mounts an Ares Predator in the turret of their Hermes cargo van. It was intended to show how ridiculously low the ranges for an ECM system really are.

I considered this very idea but discarded it because these systems are supposed to have a fall off rate. That is, for every X distance, the system loses 1 rating point. I suppose I could make it based on signal distance divided by ECM rating but I was trying to avoid having to do on the fly math to figure this out.

You do of course realise that you could just do the math in i.e. Excel ahead of time, if it's down to that issue

You just keep your logic out of this. I'm trying to be annoyed about a stupid oversight in a game system here.

Another even simpler alternative solution, could be to categorize Jammers/ECM systems into different categories.

Jammers are for handheld use and follow the standard RAW rules. Regular sized vehicles multiply the effective rating by 10, because the jammer is more powerful, and large vehicles like the ship you mention, multiply it by 100. So a Rating 10 ECM system for a car is comparable with a Rating 100 Jammer, and will have a range of 500m, and a Rating 10 ECM system for a shipsized jammer will have a range of 5000m. The effect still decrease by 1 per 5m from the source of the jamming. Sure, in this scenario, no ECCM system on any commlink will have any chance of being unaffected by the jamming, except at the very outer edge of the jamming zone, but you could argue that that would only be logical.

Alternatively you simply compare the "base" ratings, and multiply the distances you have to be from the jamming source by 10 or 100, depending on which size jamming system that's being used. I.e. an effective Sensor + ECCM of 5 being jammed by a Rating 10 ship jammer would have to be 2500m away from the ship, in order to be able to pierce the jamming effect. However, that solution would still mean that your mentioned Sensor 6+ECCM5 would be unaffected by even a ship sized jammer, which might remain on the silly side, though you could argue that it's simply down to the advanced nature ot Sensors and ECCM systems.

You can probably find some further options to modify the above, but then you start making the rules more complex.

/Kyrel

That would also work. Just need to decide what the dividing line is for each class. Thanks for the idea.