You will be able to obtain this trophy near the end of the second mission, "Welcome to the Jungle".
When you eventually make your way out of tunnels and come outside into the above-ground world again, you know you're here as there's green grass everywhere, and you'll see ceph stalkers down below taking out Cell and it'll tell you to "Hold
To Look".
If you look directly infront of you when you're on the walkway above ground, and turn slightly to the left,, you shouild see a blue building in the distance with a flashing red light, that light is the jammer.
The journey to the jammer isn't so horrible, the Ceph are easy to kill with just guns, especially to the head if you can, you can still use your powers, i.e armor mode and cloak but you can't see your energy is all.
Once you're at said Jammer, just walk up to it and simply Hold
on the side of it to shut it off, making the trophy yours.
Easy as that.