Digital voice detection apparatus and method using transform domain processing

摘要

A waveform characterizer apparatus is disclosed for extracting cepstrum pitch and spectral properties of a waveform signal such as the baseband audio output of a receiver. The apparatus employs Fourier processing, cepstral processing, magnitude detection, logarithms processing, frequency selective filtering and time/frequency windowing to extract cepstrum pitch and spectral rolloff characteristics which can then be used to determine the signal type. One application of the invention is in a digital voice/squelch apparatus.