From what I know of those things, it doesn't even have to be connected to the matrix (it's a seperate piece of equipment). It's just a device that generates a lot of signals, thereby blocking the ones you need by overloading them (at least, that's how airplane jammers work). The jammer has to be in the same room though, as otherwise it will not be as efficient. And if you activate one on the Seattle streets, you will quickly have a lot of police checking things out.
On the other hand, since it does send out a lot of signal noise, you should be able to home in on it (again, this comes from airplane jammers, where I know there exist missiles who have a 'home on jammer signal' function, where they fly towards the electric noise and then explode).