Added a band pass filter for audio output from the PC. The sound from the rig can be muted.
For band scope like operations, I usually watch with my widest filter (3.6kHz bandwidth) of the rig, so my minimum requirement is a modest band pass filter and something like a CW tuning indicator.
Three GUI sliders are used to change the filter characteristics in real time.
This figure shows a typical BPF chareacteristics, and is obtained with a built-in Gaussian Noise Source.
In these three figures the sound from the rig, when there was no significant signals on the air, is used as a noise source. The DSP filter bandwidth was 3.6kHz, 500Hz and 250Hz, respectively. The first plot is after filtering, and the second plot is before filtering in each figure.