A tone oriented voice excited vocoder

An LPC base-band vocoder is developed. The novel feature concerns the coding of the base-band. A model is set up for the base-band as a set of modulated tones. Algorithms are presented for the extraction of amplitude and phase/frequency of the tones. Implementation aspects as well as simulation results are discussed. Total bit rates in the order of 3,2-4.8 kbits are possible where approximately one half of the bits represents the base-band coding. Experiments have shown the coder to be robust to background noise.