Appendix c. fft window leakage, Captureplus ii – Cirrus Logic CapturePlus II User Manual

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CapturePlus II

DS789UM2

APPENDIX C. FFT WINDOW LEAKAGE

Windowing functions which are used to make FFT (Fast Fourier Transform) plots more informative also
generate a measurable error by spreading energy from the FFT signal peaks to the surrounding noise
floor. This results from an effect known as “window leakage”.

The following table lists the windowing functions and their associated peak signal losses that are used by
the Cirrus Logic CapturePlus II system.

Windowing Function

Peak Signal Loss

Side Lobe Attenuation

Rectangular

0 dB

Hodie 5 Term (Proprietary)

3.457 dB

125 dB

Crystal 7 Term (Proprietary)

4.203 dB

175 dB