Abstract: A differentially encoded quadrature modulation method comprises the steps of setting an index corresponding to a phase variation value constituted of input data, forming a phase value to obtain a phase-modulated output phase value from a given table and forming a channel signal to obtain in-phase (I) and quadrature (Q) channel signals from a given table using the phase value. The apparatus for performing the above comprises a signal converter for converting serially input data into two binary signal trains, a signal forming portion for obtaining channel signals, a digital-to-analog converter for converting the respective signals into two analog signals, a baseband filter for baseband-pass-filtering the signals, a phase shifter for shifting a carrier by 90.degree., first and second multipliers for multiplying the filtered signals with the carrier and phase-shifted carrier, respectively, and a mixer for mixing the respectively obtained signals and outputting a combined signal.

Abstract: A high quality voice transformation system and method operates during a training mode to store voice signal characteristics representing target and source voices. Thereafter, during a real time transformation mode, a signal representing source speech is segmented into overlapping segments, analyzed to separate the excitation spectrum from the tone quality spectrum. A stored target tone quality spectrum is substituted for the source spectrum and then convolved with the actual source speech excitation spectrum to produce a transformed speech signal having the word and excitation content of the source, but the acoustical characteristics of a target speaker. The system may be used to enable a talking, costumed character, or in other applications where a source speaker wishes to imitate the voice characteristics of a different, target speaker.