I recently installed a Cobra 29 plus in my GF's jeep. She got it from a friend of hers, no manual or anything. I got the antenna mounted and the SWR all dialed in, but I have a few questions. What is the 'dynamike' knob for? How about 'rf gain'. And on one knob there are four selections, s/rf, mod, cal, and swr. I know what they all are for except for 'mod'. What does that do? She also has a buttin that says 'NB', what's that one for?