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 [101, 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 [196, p. 89], and its properties are as follows:
Figure 3.14 plots the three-term Blackman-Harris Window and its transform. Figure 3.15 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.