The only reason to add the FFT code/mode would be to allow the use of a nanoVNA as a narrow band spectrum analyzer using the CH1 input with the disclaimer there is NO mirror suppression so interpreting what you see can be VERY difficult.
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NanoVNA Wiki:
/g/nanovna-users/wiki/homeNanoVNA Files:
/g/nanovna-users/filesErik, PD0EK
