External LNB or Mixer

If a mixer or LNB external to the TinySA is being used, populating the 'LO Frequency' box in 'preferences' appropriately will make the spectrum display show the LNB input frequency instead of its output frequency (i.e. the IF that the TinySA is actually scanning). The frequency boxes are highlighted in green to show that this is the case.

Ticking 'True' for the 'LO above....' box is for cases where the LO is above the IF, e.g C-band. When 'True' is checked, the normal spectrum display sweeps "backwards" and shows the correct frequencies, but the 3D spectrum is inverted on the frequency axis (which is not easy to fix).