| 摘要 |
PURPOSE: A method for processing voice signals inside a control station of a communication system is provided to perform preprocessing of a vocoder for entire voice PCM sample of one-frame, and to consecutively perform a vocoding process after eliminating an echo signal, so that a processing time and signal distortion are reduced through one preprocessing, and a voice quality can be improved. CONSTITUTION: A frame counter is initialized to (L-1), and a PCM sample counter is initialized to (M-1)(but, L is a frame number for vocoding and M is a voice PCM sample number necessary for starting vocoding). A vocoder input buffer(17) receives and stores one voice PCM sample loading an echo signal, outputted to a receiving terminal by passing a hybrid circuit(20) from a vocoder output buffer(13). If the PCM sample counter is not zero(0), the PCM sample counter is decreased by one(1) and the step of receiving and storing one voice PCM sample is performed until the PCM sample counter becomes zero(0). If the PCM sample counter becomes zero(0), the preprocessing of the vocoder is performed. Subtraction, between the voice PCM sample loading the echo signal stored in the vocoder input buffer(17) and a voice PCM sample loading a virtual echo signal generated from an echo signal generator(14), is performed through a subtracter(15) inside an echo signal remover(16), to remove the echo signal. The vocoder(12) performs a vocoding process, and outputs voice packet data to a transmission terminal through a packet interface unit(11). Whether a frame counter is zero(0) is decided. If not zero(0), the frame counter is decreased by one and the step of initializing the PCM sample counter is progressed until the frame counter becomes zero(0).
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