| 摘要 |
<p>A digital signal is transmitted as a plurality of (s) sequences of information symbols of uniform bit length. Each sequence occurs in a respective input channel, check words being included in the transmission through encoding. A first block of symbols, one from each input channel, is applied in a first arrangement state to a first error correcting encoder to generate a series of (p) first check symbols. Next, each symbol in the first block and each of the (p) first check symbols is delayed by a respective different delay so as to obtain a second block of symbols in a second arranging state for supply to a second error-correcting encoder. This generates a series of (q) second check symbols for transmission. First and second check symbols are generated to satisfy a respective parity check matrix with (s+p+q) columns and (p) and (q) rows respectively, of semi-cyclic codes. The delay puts adjacent symbols of the first arranging state into adjacent instances of the second arranging state and the (q) second check symbols are retro-coupled into the first encoder in accordance with the first arranging state.</p> |
