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thanks,you are right.
I have seen time-frequency representation of signals showing much
more features than the usual one obtained from Fourier transform.
The underlying maths exceed my level ,and look rather esoteric
at least for me !
At the last european signal processing conference it was a paper
on "time scale representations obtained with wavelets".
I can send you a copy if you are interested and if you provide
me your mail address.
Basically the transform for a signal s(t) is:
S(t,a) = // s(b) f((t-b)/a) db
from which is derived
S(t,a) = // g^'(au) s^(u) exp(jtu) du
where g is the analyzing wavelet which is a bell shaped pulse
I used following symbols:
up arrow ^ for fourier transform
apostroph ' for complex conjugation
pair of back slashes // for the integral symbol.
marcel
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