A class of generalized orthonormal functions

In this paper a new class of orthonormal functions which includes as particular case the Laguerre filters are introduced. These functions are defined as the product of a fixed transfer function of order n and of an all-pass filter of order n × h for any n and h. The orthogonality of these functions is proven in the general case. Moreover, the singular values of the sum of the first N_h members of this class are shown to be all equal to the orthonormalization constant.