Use the wheels to adjust the frequency shift in Hz from the center frequency of reception. Left click on a digit sets the cursor position at this digit. Right click on a digit sets all digits on the right to zero. This effectively floors value at the digit position. Wheels are moved with the mousewheel while pointing at the wheel or by selecting the wheel with the left mouse click and using the keyboard arrows. Pressing shift simultaneously moves digit by 5 and pressing control moves it by 2.
Left click on this button to toggle audio mute for this channel. The button will light up in green if the squelch is open. This helps identifying which channels are active in a multi-channel configuration.
If you right click on it it will open a dialog to select the audio output device. See [audio management documentation](../../../sdrgui/audio.md) for details.
Use this button to enable or disable the bandpass boxcar (sharp) filter with low cutoff at 300 Hz and high cutoff at half the RF bandwidth. This may help readability of low signals on air traffic communications but degrades audio on comfortable AM broadcast transmissions.
This is the squelch threshold in dB. The average total power received in the signal bandwidth before demodulation is compared to this value and the squelch input is open above this value. It can be varied continuously in 0.1 dB steps from 0.0 to -100.0 dB using the dial button.
