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FAST FOURIER TRANSFORMS WINDOWING TO REDUCE SPECTRAL LEAKAGE Input Data x(n) t Window Function w(n) t Windowed Input Data w(n)•x(n) t n=0 n=N–1 Data Window Figure 5.28 SOME POPULAR WINDOW FUNCTIONS Hamming: w(n) = 0.54 – 0.46 cos 2π πn N Blackman: w(n) = 0.42 – 0.5 cos πn 2π N Hanning: w(n) = – 0.5 cos πn 2π N Minimum 4-Term Blackman Harris w(n) = 0.35875 0 ≤ n ≤ N–1 0.5 πn + 0.08 cos 4π N – 0.48829 cos πn 2π N + 0.14128 cos πn 4π N – 0.01168 cos 6π πn N Figure 5.29 5.23
