The classic Blackman window of the previous section is a three-term window in the Blackman-Harris family (), in which one degree of freedom is used to minimize side-lobe level, and the other is used to maximize roll-off rate. Harris [97, p. 64] defines the three-term Blackman-Harris window as the one which uses both degrees of freedom to minimize side-lobe level. An improved design is given in Nuttall [185, p. 89], and its properties are as follows:
- , and .
- Side-lobe level dB.
- Side lobes roll off per octave in the absence of aliasing (like rectangular and Hamming).
- All degrees of freedom (scaling aside) are used to minimize side lobes (like Hamming).
Figure 3.8 plots the three-term Blackman-Harris Window and its transform. Figure 3.9 shows the same display for a much longer window of the same type, to illustrate its similarity to the rectangular window (and Hamming window) at high frequencies.
Frequency-Domain Implementation of the Blackman-Harris Family
Matlab for the Classic Blackman Window