User Manual

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21.3 Reference

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Input waveform

1000 point

Stored waveform

Waveform as calculated

by FFT processing

Leakage error

When the signal waveform as assumed by the FFT algorithm and the actual

waveform are different, the processing result will contain an error. This error

is called the leakage error.

Window function

・When a limited segment of the input signal is captured, a function can be

applied to reduce the leakage error.

・This function is called the window function.

・To minimize the leakage error, a suitable window should be chosen which

matches the type of input signal.

・Possible window types include rectangular, Hanning, exponential, flat-top,

minimum, force, etc. In the 8826, three window functions (rectangular,

Hanning, exponential) are available.

・Generally, the rectangular window function is most useful for single

waveforms, the Hanning window function for continuous waveforms, and the

exponential window function for attenuated waveforms.