  This paper presents a wavelet representation using baseband signals, by
exploiting Kotel'nikov results. Details of how to obtain the processes of
envelope and phase at low frequency are shown. The archetypal interpretation of
wavelets as an analysis with a filter bank of constant quality factor is
revisited on these bases. It is shown that if the wavelet spectral support is
limited into the band $[f_m,f_M]$, then an orthogonal analysis is guaranteed
provided that $f_M \leq 3f_m$, a quite simple result, but that invokes some
parallel with the Nyquist rate. Nevertheless, in cases of orthogonal wavelets
whose spectrum does not verify this condition, it is shown how to construct an
"equivalent" filter bank with no spectral overlapping.
