When playing as Carla, walk to the back right of the area to find the broken radio. In the train car closest to the radio is a flashlight; you will find batteries in it. Completely opposite the radio, past the campfire, is an iron fence you need to interact with a few times to get the antenna. Use both things with the radio and listen to all broadcasts (don't turn it back off) to unlock the trophy.
Solution taken from PlayStation Trophies:
https://www.playstationtrophies.org/game/indigo-prophecy/tro...