DSP is set to ON and the DSP level is set to 1 out of the box for both RX (Receive) and TX (transmit) modes. You can see DSP is ON by the ‘NR’ on the display. You will see ‘NR’ on the display for both RX and TX (you must press the PTT to see ‘NR’ on the display in TX mode). DSP levels can be turned OFF or adjusted by clicking on MENU and selecting ‘NR RX’ (to adjust DSP in Receive mode) or ‘NR TX’ (to adjust DSP level when transmitting). While you will notice DSP’s benefits at level 5, you may want to adjust depending on the noise conditions inside your vehicle or from the incoming signal.