How do you find out what CTCSS or DCS tones are used? Do all frequencies (or department) use these tones?The reason I ask is I have 2 local VHF police departments in adjacent areas (one is north of me, the other south) that use the same dispatch frequency. Thus I can receive both of these departments with my outdoor antenna. If I understand CTCSS correctly I can use these tones to blockout the one I'm not intrested in hearing. Is that correct?