Semi-formant vocoder with analyser on sending side - obtains frequencies of formants at receiving end by transposition of baseband frequency to required formant frequency

摘要

Frequency and amplitude of at least the second and third formant of the speech signal above the baseband are determined on the sending side by an analyser. data about these values together with the baseband are transmitted in a coded form. At the receiving end the decoded signals control a synthesiser for recovery of the speech signal. The formants are synthesised by transposition of the baseband to the formant frequency. Modulation frequency for the frequency transposition is determined by the difference of the respective formant frequency and the first formant frequency. Formant amplitudes are related to the mean amplitude of the baseband.