| 摘要 |
PURPOSE:To eliminate the deterioration in the voice signal due to miscorrection by using a specific pattern so as to supervise the frequency of error and control ling the error correction and detected bit number in response to the state. CONSTITUTION:An error correcting device has a capability of up to (N-K)-bit as the error correction function and up to (d-N-1+R)=(2+K)-bit as an error detection function, where d=4, N=1, K <= N, and the range of K is 0 and 1, two kinds of the error corrector functions exist, and in case of K=0, 1-bit error correction and 2-bit error detection are applied and in case of K=1, only the 3-bit error detection function exists. The error supervisory device collates the frame synchronizing pattern included in the voice PCM code series by each bit to supervise the frequency of occurrence of error. Since the frame pattern is constituted by 16-bits, the frequency of occurrence of error of 7 X 10<-4> or over is supervised by collating, e.g. 100 frames, that is, 1600-bits. The K of the error corrector 1 is controlled to be 0 when a few error exist and K=1 when much error exist by the output of the error supervisory device 4.
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