| 摘要 |
In a low bitrate speech encoding system, encoded bits are strongly protected against errors produced on a transmission path. A decoding side checks the transmission errors using an error check code appended to a convolution decoded output and adjusts the decoding output depending on the results of check of transmission errors. At this time, it is necessary to maintain continuity of speech signals after speech decoding. To this end, a convolution decoder 16 convolution decodes the convolution coded output from the encoding device to provide a convolution decoded output of a crucial bit set with the appended error check code and a bit set excluding the crucial bit set. A CRC code comparator- frame masking unit 15 compares the CRC check code appended to the convolution decoded output from the convolution decoder 16 to the CRC check code computed from the bit group excluding the crucial bit set to adjust the convolution decoded output. <IMAGE>
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