I have a 396xt and a 996xt and primarily listen to Irving texas police and fire. It is a trunked system and until lately the control freqs changed a couple of times a day. Recently, the control freq and the annoying noise that goes with it seems to change every few minutes. It's really annoying and happens on both radios so I have to assume something in their system has changed. Has anyone else encountered this problem and what do you do about it?