The Spectral Flatness view shows the data that is collected from the preamble at the channel estimation step. The deviation of the Spectral Flatness from the average (over all of the carriers) is shown in dB. A mask that conforms to the specification is overlaid on the trace. Green color on the mask indicates pass, and red color on the mask indicates regions of the mask where the signal fails.

This mask is referenced from the average of all subcarrier amplitude values. The numerical result that is displayed in this view is the adjacent subcarrier flatness (in dB).