Howtosignalprocessing
- What is meant by spectral leakage?
- What causes spectral leakage?
- Why is spectral leakage bad?
- How do you fix spectral leakage?
What is meant by spectral leakage?
Leakage, more explicitly called spectral leakage, is a smearing of power across a frequency spectrum that occurs when the signal being measured is not periodic in the sample interval.
What causes spectral leakage?
Spectral leakage results from an assumption in the fast Fourier transform (FFT) and discrete Fourier transform (DFT) algorithms that the time record exactly repeats throughout all time. Thus, signals in a time record are periodic at intervals that correspond to the length of the time record.
Why is spectral leakage bad?
The bad news is that spectral leakage cannot be avoided in general. The energy in a signal associated with each frequency has to go somewhere in the DFT, and if the frequency does not correspond to one of our analysis frequencies, then it will spread out.
How do you fix spectral leakage?
We have seen that spectral leakage is reduced by tapering the digital signal by a window function before the DFT takes place. A generalization of this technique is the short-time discrete Fourier transform (STDFT).
