Use mouse wheel to increment/decrement frequency by Step amount.
Enter frequency in kHz and hit Return or press Set Frequency (kHz).
Tick the 'Activate cursor' box to enable cursor: use wheel or click to select cursor location.
Click on the 'Autoscale' button to set amplitude range to fit current spectrum
The 'Max hold decay' setting adjusts how slowly the max hold trace decays
If the spectrum display/waterfall is focused, keyboard shortcuts are active:
Press space to toggle pause/run mode
'f' to toggle fullscreen mode
'c' to step through the colormap options
up/down arrow shifts the spectrum trace up/down
left/right arrow increases/decreases amplitude range
's'/'w' to increase/decrease size of spectrum display
'+'/'-' to increase/decrease FFT averaging
'm' to toggle max hold mode
Web Server by John Melton, G0ORX (https://github.com/g0orx/ka9q-radio) ka9q-radio by Phil Karn, KA9Q (https://github.com/ka9q/ka9q-radio) Onion Web Framework by David Moreno (https://github.com/davidmoreno/onion) Spectrum/Waterfall Display by Jeppe Ledet-Pedersen (https://github.com/jledet/waterfall)