Appendix A
565
Leakage appears in a
FFT spectrum, if the
assumed waveform
differs from the
original waveform.
The FFT algorithm calculates frequency components which “leak”
into the pure spectrum. This is illustrated in the following picture.
Correct and Incorrect Time Record
Leakage makes it impossible to detect minor signal components.
Coherent sampling
avoids leakage.
The optimal way to avoid leakage is to sample coherently.
Coherent sampling ensures that the time record includes a whole
number of signal periods (the UTP). These periods can be
seamlessly concatenated.
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