METHOD AND APPARATUS FOR SUBSAMPLING PHASE SPECTRUM INFORMATION

A method and apparatus for subsampling phase spectrum information includes a speech coder for analyzing and reconstructing a prototype of a frame by using intelligent subsampling of phase spectrum information of the prototype. To analyze the prototype, the speech coder produces a phase parameters of a reference prototype, generates phase parameters of a current prototype, and correlates the phase parameters of the current prototype with the phase parameters of the reference prototype in multiple frequency bands. To reconstruct the prototype using linear phase shift values, the speech coder produces a phase parameters of the reference prototype, generates a set of linear phase shift values associated with the prototype, and composes a phase vector from the phase parameters and the linear phase shift values across multiple frequency bands. To reconstruct the prototype using circular rotation values, the speech coder produces a set of circular rotation values associated with the prototype, generates a set of bandpass waveforms in multiple frequency bands, the bandpass waveforms being associated with the phase parameters of the reference prototype, and modifes the bandpass waveforms based upon the circular rotation values.