
Windowed Fourier Transforms ◾ 61
pixels and includes signals with high and low frequencies. Figure2.31
shows the intensity of the modulated fringe pattern at the 100th row. is
fringe pattern can be considered a nonsinusoidal signal because of the
saturated exposure. Figure2.32 shows the power spectra of the original
and modulated fringe pattern at the 100th row. e fundamental spectral
component of the modulated fringe pattern is superposed by the other
higher-order spectral components, which makes it impossible to lter out
the fundamental spectral component accurately. e instantaneous fre-
quency of the fringe pattern at the 100t