DATA DEMODULATING DEVICE

PURPOSE:To prevent the characteristics of an automatic equalizer and an automatic phase control circuit from being disordered owing to an error in decision making by controlling the quantities of feedback of an error signal to the automatic equalizer and automatic phase control circuit according to the reliability of the decision result of a viterbi decoder. CONSTITUTION:The output signal 114 from the viterbi decoder 7 is a coefficient (called a feedback number here) between 0 and 1 which indicates the reliability of a signal 108. This feedback coefficient is closed to 0 when the reliability is low and close to 1 when high. This feedback coefficient is a coefficient obtained by converting properly the difference between the smallest passmetric and the 2nd small passmetric. This feedback coefficient is led to multipliers 12 and 13 and multiplied by signals 109 and 110 respectively to generate signals 112 and 113. The signals 112 and 113 are obtained by attenuating the signals 109 and 110 according to their reliability and the signals 112 and 113 are fed back to the automatic phase control circuit and automatic equalizer to reduce the quantity of feedback of the error signal relatively when the reliability of decoded data is low, evading the adverse influence of an error in decision making.