0 0 0Go to Spaced Out Level in Rose's Room Chapter, find the satellite dish and use it as in this video :
0 0 0In the level Rose’s Room: Spaced Out you'll reach an area with portals you need to go through. For this particular achievement you'll need to reach the second set of portals and then enter the sort of golden looking portal. Entering it you'll see pillows stacked. Go left and jump up then jump over to the lamp on the other side and continue up. At the top you'll reach an antenna. One of you enter it and there will be 4 signals to look for and listen to. After listening to the fourth one the achievement will pop.Alternatively you can teleport closer to the area if you found the Laser Tennis minigame during the first playthrough and then just exit that and go up to the second set of portals.