W
f
(a, b) ¼
ð
1
1
f (x)c
a,b
(x)dx (7:13)
This representation provides the time–frequency localization, but the representa-
tion is highly redundant or overcomplete. Note that as the wavelet becomes
broader, the time resolution becomes worse while the frequency resolution im-
proves. Conversely, as the wavelet becomes narrower, the time resolution improves
but the results of frequency analysis become less certain. Discretization of a, b
and special choices of c(x) lead to wavelet orthonormal bases, or wavelet series
expansions.
7.2.2 Wavelet Series Expansion
The wavelet series expansion is analogous to the Fourier series, in that both
methods represent continuous-time signals with a series of discrete coefficients.
A set of basis functions is formed by scaling ...