This is an extremely missable and time consuming achievement that can only be done in New Game+, due to the fact that some broadcasts are found after the point of no return. There are a total of 51 broadcasts in all.
Because this is sort of difficult to explain without the use of pictures, I'm going to provide a link to my guide on Steam. It goes over where to find every frequency, and where to find Lady Anatta.
http://steamcommunity.com/sharedfiles/filedetails/?id=811136...