A magneto-optical recording and reproducing apparatus achieving an improvement in high density recording and bit error correction rate. The magneto-optical recording and reproducing apparatus comprises coding and modulating means for (1,7) RLL encoding and then NRZI encoding a digital information series {Ai}; recording and reproducing means for recording the encoded series {ai} to a magneto-optical recording medium, and reproducing an analog signal from the medium as elementary waveform sequence e(t) using an optical head; a transversal filter type waveform equalizer for waveform equalizing elementary waveform sequence e(t) by applying the transfer function (1+2D+2D2+D3) of the PR(1,2,2,1) encoding method to the elementary waveform of the encoded sequences, where delay operators D have a delay time of the encoded sequence cell width Tb; a low pass filter; an A/D converter for sampling and quantizing the equalized waveform sequence x(t); and a Viterbi decoder for comparing the A/D converter output {ai} with a particular expected value, and determining the most probable path as decoded sequence {Ai}. The transfer function of PR(1,2,2,1) encoding well approximates the combined transfer function of the recording and reproducing means and the waveform equalizer, achieves strong suppression of interwaveform interference, and achieves high density recording. The Viterbi decoder has a long minimum free distance and an improved error correction rate.
Information recording and reproducing apparatus