Read my guide or watch this guide.
Credit: Batman Arkham Videos
( 1 of 3 ): Starting off, you will realize as soon as you try and decode the trigger, the communication stops working. So you need to find all 3 communication jammers and then return to decoding the trigger. This starts off with you having to go near the museum. I recommend you just swiftly take them out, by charging into them because if they get their hands on the weapons it might kill you. After doing so, disruptor number 1 destroyed.
( 2 of 3 ): For this one, you should go and follow the signal. As soon as you make it there, I suggest you do this as quietly as you can. They are armored. After taking them out you will have done disruptor number 2.
( 3 of 3 ): This last one is pinpointed on your map, go to it. Try and wait patiently for the guarding goons to go into their patrol, once they do this sneak in the subway station. Double takedown the both that are watching the stairs. Navigate down the stairs, across through the train track until you might see people. Take them out and then you'll have to take the whole room full of armored guards. Destroy the last disruptor and then venture back to Penguin's museum to continue and get an easy steam achievement.