Patent ID: 8015499

Claim:
A decoder, comprising: a soft-input soft-output decoder for decoding channel reproducing signals which have inter-symbol interference; a soft-input decoder for decoding a soft output of the soft-input soft-output decoder; and a weighting computing unit for detecting both sided amplitude fluctuation of a soft-input signal of the soft-input soft-output decoder, and outputting a weight value according to a drop in amplitude, wherein a soft output value of the soft-input soft-output decoder decreases the soft output value by the weight value, and a decoding process is performed by propagating reliability information between the soft-input soft-output decoder and the soft-input decoder, and wherein the weighting computing unit comprises: an absolute value encoding section for reflecting the soft-input signal at an amplitude center value; a moving average computing section for computing a moving average value in a predetermined range; a normalization computing section for dividing the moving average value by an average value of all the absolute value signals; and a weighting generation section for generating the weight value as “1” when the normalization computing value is “1” or more, and as the normalization computing value when the normalization computing value does not exceed “1”.