The practical method for reducing a leakage error
is to apply weighting so that the beginning and the end of the time
window that is to be cut out are zeroed smoothly. Such weighting
function is referred to as a time window function. The window
function that is most generally used by the FFT analyzer is a
Hanning window.
Table1 Typical window functions used by the FFT Analyzer
| Type | Equivalent noise bandwidth | Level accuracy | Main application |
|---|---|---|---|
| Rectangular | Δf | -3.9 dB | Transient signals |
| Hanning | 1.5 Δf | -1.42 dB | General signals and continuous signals |
| Flat top | 3.6714 Δf |
±0.1 dB | Periodic signals |
Revised:(2009/11/16)
