公开(公告)号：US3789359A

公开(公告)日：1974-01-29

申请号：US3789359D

申请日：1972-10-04

Applicant: HARRIS INTERTYPE CORP

Inventor： CLARK G ,  DAVIS R

IPC: H03M13/33 ,  H04L1/00 ,  G08C25/00 ,  H04L1/10

CPC classification number: H04L1/0059 ,  H03M13/33

Abstract: Apparatus for synchronizing a decoder of convolution codes with a received stream of convolutional code data. Synchronization is achieved with respect to such problems as bit polarity inversion and incorrect boundaries of branch intervals by examining a number of trial message sequences. The trial message sequences are obtained by an algorithm suggested by Viterbi involving selection of one survivor sequence terminating in each data state of the code. When the decoder is synchronized with the received data stream, the survivor data sequences are very probably all identical at a branch interval near the older-data end of the sequences. When the decoder is not synchronized, the survivor sequences, with high probability, differ from each other at that branch interval. Loss of synchronism is detected by simultaneously examining the survivor sequences at a branch interval located at a selected number L of branch intervals before the last-received data, L being less than or equal to the decoding depth. If the survivor sequences are not unanimous at depth L a count is registered. If the number of such counts occurring within a test period of B successive branch intervals exceeds a predetermined threshold T, branch synchronism is presumed to be incorrect and a search is initiated for correct synchronism.

Abstract translation: 用于使卷积码的解码器与接收的卷积码数据流同步的装置。 通过检查多个试用消息序列，实现了比特极性反转和分支间隔边界错误等问题的同步。 试验消息序列通过由维特比建议的算法获得，涉及选择终止于代码的每个数据状态的一个幸存者序列。 当解码器与接收到的数据流同步时，幸存者数据序列在序列的较旧数据端附近的分支间隔可能全部相同。 当解码器不同步时，具有高概率的幸存者序列在该分支间隔处彼此不同。 通过在位于最后接收数据之前的分支间隔的选定数量L的分支间隔处同时检查幸存者序列，L小于或等于解码深度来检测同步丢失。 如果幸存者序列在深度L上不一致，则记录计数。 如果在B个连续分支间隔的测试周期内发生的这种计数的数量超过预定阈值T，则假定分支同步不正确，并且启动搜索以进行正确的同步。

公开(公告)号：US3789360A

公开(公告)日：1974-01-29

申请号：US3789360D

申请日：1972-10-13

Applicant: HARRIS INTERTYPE CORP

Inventor： CLARK G ,  DAVIS R

IPC: H04L1/00 ,  H04L1/10 ,  G08C25/00 ,  H03K13/34

CPC classification number: H04L1/0054

Abstract: A decoder for correcting and decoding convolutional data. Decoding of each digit of sequentially received data is postponed until a plurality of subsequent digits have been received. A message digit is then decoded by comparing the received sequence of data with a limited number of possible messages. The possible message which correlates best with the sequence of convolutional data that was received is temporarily assumed to be the correct sequence for purposes of decoding only the first message digit or perhaps the first few message digits of the data sequence currently being considered. The limited number of possible messages to be compared with the received data are selected at each branch interval by choosing one sequence terminating in each data state. During decoding, the possible messages are represented as sequences of branch transitions among a predetermined number of data states. The transitions among states are traced step by step through the possible message sequences to ascertain the data state of a survivor sequence at the decoding depth. The data state of the highest correlated survivor path is then interpreted into a decoded message bit.

Abstract translation: 用于校正和解码卷积数据的解码器。 顺序接收数据的每个数字的解码被推迟直到接收到多个后续数字。 然后通过将接收到的数据序列与有限数量的可能消息进行比较来解码消息数字。 暂时假定与接收到的卷积数据序列最相关的可能消息是正确的序列，用于仅解码当前正在考虑的数据序列的第一消息数字或最初几个消息数字。 通过选择在每个数据状态终止的一个序列，在每个分支间隔选择与接收数据进行比较的可能消息的有限数量。 在解码期间，可能的消息被表示为预定数量的数据状态之间的分支转换序列。 通过可能的消息序列逐步跟踪状态之间的转换，以确定解码深度处的幸存者序列的数据状态。 然后将最高相关幸存路径的数据状态解释为解码消息位。