| 摘要 |
PURPOSE:To increase the compression effect through a simple constitution and thus to obtain the excellent reproduced voice by eliminating the redundant continuation part of the vocal sound to transmit only the frame information and then giving the interpolation reproduction to the continuation part at the time of demodulation. CONSTITUTION:The PCM aural signal given from input terminal 11 with sampling of 8K Hz and quantization of 8 bits applied is divided 12 into 1-frame 80 samples (10ms). Then the signal of each frame is sent to arithmetic part 13 to undergo the calculation of the average power and the zero cross number to decide the frames for the silence, voiceless sound and vocal sound each; and these frames are added to the initial sample of each frame. While the frame-divided 12 PCM signal is supplied also to switch circuit 14. And the silence frame, voiceless frame and vocal frame are distributed fo frame eliminating part 15, but rearranging part 16 and steady frame omitting part 17 respectively. In case the changing rate is under the fixed level between the adjacent frames of the frame average power at part 17, the information showing this is sent from arithmetic part 13. And the redundant continuation parts excepting the frame information are eliminated for the subsequent frames. |
