Walsh-transform coding of the speech residual in RELP coders

A method is described for encoding the residual speech signal in residual-excited linear predictive coders. In this method, a low-sequency baseband of the residual is transmitted by encoding the coefficients of the lower half of the Walsh spectrum. Techniques for reconstructing the upper portion of the spectrum are discussed. The resulting algorithms are simple to implement and simulation studies have shown that a bit rate of 10 kbits¿1 can be achieved.