In broadcasting stations, the data transfer rate of phase change optical disk systems for HDTV must be more than 100 Mbps. A conventional phase change disk system must drive a laser diode with multiple pulses in order to record data. However, this requires a large circuit if the data transfer rate is more than 100Mbps. So high linear velocity must be needed for high transfer rate. It is expected that same cooling effects as adding multiple pulses appear at high linear velocity. The result of a read/write experiment without multiple pulses that a bit error rate of about 10^<-6> was obtained at 100 Mbps when random data was recorded onto a phase change disk without multiple pulses with using RLL(1, 7)code and PRML at a read/write linear velocity of 25 m/s.
An HDTV optical disk camera system needs to be established. To realize such a system, high-transfer-rate of more than 100 Mbps per channel is required. We measured the transfer function of the optical disk channel in order to make simulation software. Through the simulation and the recording experiments, we have confirmed that the RLL(1, 7)coding and PR(1, 1, 1)ML channel are suitable for the high-transfer-rate optical disk system. In the recording experiment, bit error rate of less than 10^<-5> is achieved
The perfomance comparison of the various partial-response-maximum-likelihood(PRML)systems for advanced optical recording is described. The bit-error-rate(BER)performances of PR(1, 1, 1, 1)ML, PR(1, 2, 2, 1)ML, PR(1, 3, 3, 1)ML, PR(3, 4, 4, 3)ML systems for EFMPlus code and rate 8/14 ARL code are obtained by computer simulation. The BER performance of the rate 8/14 ARL code is superior to that of the EFMPlus code. The best PR targets for the EFMPlus code and rate 8/14 ARL code are PR(3, 4, 4, 3)and PR(1, 2, 2, 1), respectively. The rate 8/14 ARL code has a 0.7-dB gain in the required SNR, compared to the EFMPlus code, and is more robust against tilt and defocus than the EFMPlus code.
A new run-length-limited(RLL)code for optical disks is described. It is an asymmetrical(d_0, d_1)=(2, 1)code, i.e., its minimum mark length is three channel bits to maintain the read back signal power, and its minimum space length is two channel bits to maintain the partial-response maximum likelihood(PRML)performance. It encodes 8 user bits into 14 channel bits, i.e., it has a better window size. Compared with the EFMPlus code, the ARL code has a 0.7dB gain in the required SNR at a BER of 10^<-4>. The power spectal density in the servo frequency band is -23dB.
A new error-correcting code(ECC)for optical disks is proposed. It is based on a product code, and symbols in each row are interleaved using individual interleaving rules. Maintaining code rate and error-correcting performance for random errors and long burst errors, the proposed product code is more effective for short burst errors than a conventional product code.