Abstract: Correct digital demultiplexing is the precondition of recovering the information in PDH signals.To realize the reliable communication in the high BER environment，an improved high error-resilient digital demultiplexing method using residual source redundancy is proposed.The originality of this approach is based on a rule discovered in this paper.That is it has plenty of redundancy information in the PCM sources of base-group data.Simulation results show that the performance of this method can be significantly improved compared with the majority decision recommended by ITU.It has low computational complexity and can be implemented easily in software or hardware.Furthermore，for the rule exploited exists widely in PDH communication systems，this approach has great practicability.

Key words: joint source-channel decoding, digital demultiplexing, justification, majority decision

摘要： 正确的数字分接是PDH数字群路信号信息还原的前提。在高误码信道环境下，为实现可靠通信，提出了利用信源残留冗余来实现高容错数字同步分接的改进算法。算法通过挖掘PDH数据最底层的PCM信号中所残留的冗余，根据码速调整对PCM残留冗余的影响，来增强码速恢复的判断依据。实验的仿真结果显示算法较为彻底地解决了群路分接的滑帧问题，在容错性和准确性上比ITU推荐的多数判决法有显著提高，且较低的计算复杂性使其易于用软硬件实现。由于揭示的规律在大容量PDH通信中是普遍存在的，因此提出的算法具有很大的实用性。

关键词: 联合信源信道译码, 数字分接, 码速调整, 多数判决法