A study on (1,7) coded PRML systems using a double clock weighted Viterbi decoding for optical disc recorder

Bit error rates (BER) for playback of (1,7) code employed in optical disc r ecording were simulated using an ideal (Gaussian) playback waveform, with p layback being performed by PRML (Partial Response Maximum-Likelihood) combi ning a partial response equalizer and a double clock weighted Viterbi decod er. It was found that best BER occurs for PR(2,3,3,2) +7/10 level Viterbi d ecoding at a weighted Value of w = 0.5 for data consisting of 10(7) symbols . For a minimum bit length of 0.28 mu m, BER of 10(-4) and less than 10(-6) was obtained for SN ratios of 15.6 dB and 17.7 dB, respectively. And for a minimum hit length of 0.20 mu m, BER of 10-4 and less than 10(-6) was obta ined for SN ratios of 16.7 dB and 18.8 dB, respectively. These results demo nstrate the feasibility of a minimum bit length of 0.26 mu m in current opt ical disc recorders.