S E T U P F O R M C H A P T E R 8
Hanning, Hamming: These windows are based on a raised cosine shape. In addition to providing
continuity (Hanning) or near continuity (Hamming), these both provide a shape that makes the
slopes of the signal agree at the beginning and the end of the signal buffer. This filter provides for
both good
Window Mathematical Description Graphical Depiction
Hanning
Hamming
Figure 84: Hanning and Hamming Windows (Kaiser also displayed)
Welch: This applies a shaping function to the data before the FFT is computed. The figure gives its
shape.
Window Mathematical Description Graphical Depiction
Welch
Figure 85: Welch Window
This picture is from a 512 long Welch Window. We actually use a 4096 long window but this does
illustrate the qualitative features. Notice that at the left and the right end, we have forced the
continuity by applying this tapering function. This continuous move to zero at the endpoints
mitigates the “key-click” phenomenon that would otherwise result from the boxcar or rectangular
window.
88 FlexRadio Systems
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