Basic FAQ for FFT Analyzer
Question number FAQ-0751
What kinds of time window functions are there, and how are they distinguished in use?
A practical way to reduce leakage error is to apply a weighting that smooths the beginning and end of the time window to zero. This type of weighting function is called a time window function. The most commonly used window function in FFT analyzers is the Hanning window.
Table 1 summarizes representative window functions and their applications.
Table 1: Typical Time Windows Used in FFT Analyzers
| Type | Equivalent Noise Bandwidth | level of accuracy | main uses |
|---|---|---|---|
| Rectangle | Δf | -3.9 dB | transitional signal |
| Hanning | 1.5 Δf | -1.42 dB | General use, continuous signal |
| Flat top | 3.6714 Δf | ±0.1 dB | periodic signal |
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Last updated: November 16, 2009