| 摘要 |
A forward error correcting apparatus employing the Kasami algorithm for trapping errors in a half-rate Golay codeword. The Golay code is defined as an (n, k, t) or (23, 12, 3) polynomial code in which each codeword is n=23 bits long, contains k=12 data bits and (n-k)=11 redundant check bits, and corrects up to a maximum of t=3 errors. The forward error correcting apparatus includes an input data register circuit arranged to receive, store and shift therealong the data bits of the Golay codeword, and a Golay shift register circuit arranged to receive, store, shift and recirculate therein the data and check bits of the Golay codeword. The codeword shifted and recirculated within the Golay shift register circuit is divided by a generator polynomial g(x) expressed by x11+x10+x6+x5+x4+x2+1 to derive a syndrome word which is examined in a Kasami error trap circuit in accordance with the Kasami algorithm to detect one of three possible error situations. Should any one of the three possible error situations exist, the erroneous bits in the codeword are corrected.
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