As is seen from the analysis above, modified ZFFT
method can well solve the problem when the given signal
contains components with frequency close to each other. It
is a novel method for harmonic analysis. We all know in
traditional harmonic analysis methods when confronted
with harmonic components with a close frequency interval
the number of points of sample must be increased greatly
to a large extent if the frequency of sample remains
unchanged. Spontaneously computing speed will decrease
with the points of FFT increasing. However the proposed
modified ZFFT method can meet all requirements above.