I have a Radio Shack Pro 2021 scanner that I keep in my house just to listen to fire department dispatch calls. I have a discone up about 40 feet and the problem is the scanner has no tone decoder on it so on one frequency I may hear three or possibly four fire departments from far away. Does anyone know a way that I can add a tone decoder to this radio so that I can program in only the tones I want to receive? I've heard there may be some software that may be able to do this but I'm just not aware of it. Any help would be appreciated.