FUNDAMENTAL RESEARCH ON MULTI-LEVELIZATION OF MAGNETO-OPTICAL RECORDING

本课题研究了磁光记录在高密度存储中的多电平化效果。本研究的主题仅限于“光调制”和“磁场调制”两种方法。为了避免额外引入更高的成本，我们的项目基本上是基于一个限制，即多级记录系统是通过对二进制记录系统应用传统的磁头和介质来实现的。我们可以通过选择与代码符号0、1或2成比例的写脉冲宽度来克服这个问题。接下来，在12Mbps到24Mbps的传输比特率范围内，计算机模拟了用于实现误码率（BER）为10^<-4>的回读点所需的CN比率，前者是当前状态的上限。结果表明，对于(1)光调制方法：使用（1,7）码+PR (1,2,1) ML实现的边缘记录是比特率在12 ~ 20 Mbps范围内的最佳组合。在24Mbps时，3B2T代码+PR(1,2,1) ML组合是最有效的。(2)磁场调制方法：3B2T码+PR (1,1) ML（或PR(1,2,1) ML）是比特率在12 - 20mbps范围内的最佳组合，而2B1Q码+PR (1,2,1) ML是24 Mbps的最佳组合。此外，我们还研究了网格代码和二维代码对下一代代码的有效性。

This research project has investigated the effectiveness of multi-levelization of magneto-optical recording for higher density storage.The subject of the investigation is limited to both "light modulation" and "magnetic field modulation" methods.In order to avoid any additional introduction of higher costs, our project has fundamentally been based on a restriction that the multi-level recording system is to be realized by applying the conventional head and media for the binary recording systems. We could overcome this problem through the selection of writepulse widths in proportion to the code symbols 0,1 or 2.Next, the required CN ratios at the read back points used to attain a bit error rate (BER) of 10^<-4> have been computer-simulated at transmission bit rates ranging from 12Mbps to 24Mbps, the former rate being the upper limit one for the present state.The results showed that, for the(1)light modulation method : edge recording achieved by the use of a (1,7) code+PR (1,2,1) ML is the best combination at bit rates ranging from 12 to 20 Mbps. At 24Mbps, the 3B2T code+PR(1,2,1) ML combination is the most effective.(2)magnetic field modulation method : the 3B2T code+PR (1,1) ML (or PR (1,2,1) ML) is the best combination at bit rate ranges 12 - 20 Mbps while the 2B1Q code+ PR(1,2,1) ML one is the best at 24 Mbps.Additionally, we also investigated the effectiveness with trellis codes and two-dimension codes for next generation codes.