Sequential decoder and system for error correction on burst noise channels by sequential decoding

摘要

sequential decoder (32) for error correction on burst and random noise channels using convolutionally encoded data interacts with a de-interleaver (30) which time- demultiplexes data from a data channel. The decoder includes a memory (44) for storing a table of likelihood values which are derived from known error statistics about the data channel. The decoder removes (38F) an encoded subblock of data from the de-interleaver and enters it into a replica (38E) of the convolutional encoder which calculates a syndrome bit from a combination of the presently received subblock together with a given number of previous subblocks. For each received bit, an Indicator bit is calculated (40) which is a function of the difference between the current path in a convolutional decoding tree and the received sequence. The sequential decoder employs the syndrome bit (38A) together with burst indicator bits (40E) to calculate (42) a table address in a table (44) of likelihood values and error pattern values.