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公开(公告)号：US3873920A
公开(公告)日：1975-03-25
申请号：US42663173
申请日：1973-12-12
CPC分类号： H03M7/4025 , H04L7/043 , H04L7/048
摘要： Framing or block synchronization of digital information signals grouped in blocks of variable length is provided by preceding each block with a synchronization code word. Each synchronization code word is error correction encoded in accordance with a BCH code to indicate the number of information bits in the following block and, hence, the location of the next succeeding synchronization code word. Since only the synchronization code words are error correction encoded, they can be distinguished from the information bits to obtain synchronization. A synchronization receiver acquires synchronization upon the occurrence of an error-free synchronization code word in the incoming signal. Synchronization is maintained thereafter by utilizing the inherent error correction capability offered by the BCH code to correct up to two errors in each received synchronization code word before decoding it to locate the next synchronization word. If, however, three errors are detected in a received synchronization word, synchronization is assumed to be lost and synchronization is thereafter recovered with the occurrence of a succeeding error-free synchronization code word in the incoming digital signal. Two receiver embodiments are disclosed which perform the above-described operation. The first embodiment is adapted to perform a general type of framing synchronization, while the other embodiment is specifically adapted to provide video synchronization.
摘要翻译： 由前面的每个块提供具有可变长度的块的数字信息信号的成帧或块同步，具有同步码字。 每个同步码字根据BCH码进行纠错编码，以指示随后块中的信息比特数，并因此指示下一个后续同步码字的位置。 由于仅对同步码字进行纠错编码，所以可以将其与信息比特进行区分以获得同步。 同步接收器在进入信号中发生无差错同步码字时获得同步。 此后，通过利用由BCH码提供的固有的纠错能力，在解码之前对每个接收到的同步码字中的两个错误进行校正以定位下一个同步字，从而维持同步。 然而，如果在接收的同步字中检测到三个错误，则假设同步被丢失，然后在输入数字信号中出现随后的无错误同步码字的同时被恢复。 公开了执行上述操作的两个接收机实施例。 第一实施例适于执行一般类型的成帧同步，而另一实施例特别适于提供视频同步。
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