Patent ID: 7991078

Claim:
A signal processing apparatus adapted to process a signal transmitted via a transmission path causing a waveform represented by a signal value of a specific symbol to have stationary distortion depending on a value of a symbol transmitted before the specific symbol, comprising: acquisition means for acquiring the signal value of the specific symbol from the signal transmitted via the transmission path; distortion removing means for removing, from the waveform represented by the signal value of the specific symbol acquired by the acquisition means, distortion predicted to occur in the waveform represented by the signal value of the specific symbol in accordance with a characteristic of distortion occurring in the waveform represented by the signal value of the specific symbol, depending on the value of the symbol transmitted before the specific symbol, thereby producing a distortion-removed waveform; comparison value calculation means for calculating a comparison value for each of values allowed to be taken by the specific symbol, by subtracting, from a signal value of the distortion-removed waveform calculated by the distortion removing means, a signal value predicted as that of the specific symbol in accordance with a characteristic of the waveform represented by the signal value of the specific symbol depending on the value of the symbol transmitted before the specific symbol, for each of the values allowed to be taken by the specific symbol; determination means for determining the value of the specific symbol of the signal transmitted via the transmission path, by comparing the comparison values of the respective values allowed to be taken by the specific symbol, detecting a smallest comparison value of all comparison values, and employing, as the value of the specific symbol, a value allowed to be taken by the specific symbol for which the smallest comparison value is obtained in the calculation of the comparison values; suspected error detecting means for generating an error suspicion level value indicating a degree of suspicion of being incorrect for the value of each of a predetermined number of symbols, on the basis of values previously determined by the determination means for a predetermined number of symbols transmitted before the specific symbol, the characteristic of the distortion, and the smallest comparison value; and error correction means for correcting the values previously determined by the determination means for the specific symbol, in accordance with the error suspicion level values generated by the suspected error detecting means.