Using these switches, dsd -f1, dsd -fi, dsd -fn, unless someone is talking or you are hearing a control channel, you aren't going to hear any audio and will not see anything scroll on your screen.
If you are using the switch (-xr) to monitor a TRBO signal and are constanly hearing what sounds like scrambled audio, then you are monitoring with the wrong switch, It would need to be (-fr) when you start. TRBO will constanly having data scrolling on the screen, even when no one is talking.