Soft error-trapping decoding of cyclic codes

An error-trapping (ET) decoder is described which effectively uses softly-quantised demodulator output levels as an integral part of the decoding process. This soft ET decoder operates on multilevel symbols, which belong to a Galois field and represent the quantised demodulator output levels of a communication system. The procedure differs from other approaches to soft-decision decoding which employ conventional hard-decision decoders where, as separate items, the digit reliability measures are used in an ad-hoc fashion.