I wonder if it will be possible, in a future sourcebook, to do the exact opposite. Like having a grenade that is set to detonate immediately, but it continuously gets a wireless signal saying, dont detonate yet. Using a jammer in that case would be very unhealthy, if you are close enough that is.
I've heard of explosives like this being used by the IRA (though it was a conversation at uni, so I'm not positive about how reliable it might have been), though the mechanism isn't that complicated. It's pretty much the same as the principle on an egg timer (and any explosives that might be linked to such), where one circuit acts as a safety and when a battery or radio signal would stop sending current through that circuit it would then detonate.
So has it been made official somewhere that the noise reduction frommultiple datajacks is cumulative?
I could see how multiple jammers might provide diminishing marginal returns, but I don't logically see how multiple data jacks would reduce noise. You're still going through the same security systems, bandwidth, and other problems. Oh well.