FFT in oscilloscope measuring Frequency spectrum
Searching for FFT Peaks
  5) Press Threshold and turn the Entry knob to
  specify the threshold level necessary to be considered a peak.
  6) Press Excursion to specify the amplitude above the FFT waveform's noise
  floor necessary to be recognized as a peak.


Source: Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide p. 95