Wavelet transforms for discrete-time periodic signals are developed. I
n this finite-dimensional context, key ideas from the continuous-time
papers of Daubechies and of Cohen, Daubechies and Feauveau are isolate
d to give a concise, rigorous derivation of the discrete-time periodic
analogs of orthonormal and symmetric biorthogonal bases of compactly
supported wavelets. These discrete-time periodic wavelets are expresse
d in terms of circular FIR filters, and thus lead to fast wavelet tran
sforms whose complexity is order N.