RESEARCH ON HIGHER DENSITY RECORDING FOR HARD DISK SYSTEM BASED ON TRELLIS METHOD

本计画结合信号处理技术，包括维特比检测器，发展出一种新的强健记录码，以应用于高密度的硬盘记录系统。近来，许多研究者注意到，在传统的简单（d，k）极限和一维二阶技术的限制下，新的编码的发展将非常困难。他们还认为，未来的编码方法必须包括以下一项或几项技术：（1）提高编码增益，（2）实现多级记录，（3）扩展到多道记录。部分缓解均衡器和维特比检测器可以用有限状态自动机理论来建模。我们已经成功地开发了几种新的鲁棒TCPR第一年，我们研制了码率为eta = 1/2，2/3和3/4的一维TCPR（1，1）码，并与NRZI码加PR（1，1）ML方法的普通记录系统的误码率（BER）特性进行了比较，在归一化记录密度K = 2.4（即当时可实现的最高密度）时，我们证实了前者优于后者的超验性，并在次年验证了在K = 1.2时，TCPR（1，1）系统在误码率方面优于TCPR（1，-1）系统<greater than or equal>。我们也开始研究在TCP中引入二维技术的可能性。在最后一年，几个新的鲁棒码参与了所有的二维技术，MTR（最大转移运行）属性和网格函数已经开发出来。

This project has developed new robust recording codes combined with signal processing techniques included Viterbi detector for higher density recording of hard disk system based on trellis method.Recently major researchers have noticed that the splendid development of new codes would be very difficult under the constraints of conventional simple (d, k) limits and one-dimensional two level techniques. They also suggested that the future prospective coding methods must be involved one or some following techniques,(1) improvement of coding gain,(2) realization of multi-level recording,and(3) expansion to multi-track recording.Our idea originates from the fact that evey recording codes, partial response (PR) equalizers and Viterbi detectors can be modeled after finite state automation theory.We have successfully developed several new robust TCPR(trellis coded PR) codes which use the combination method of all models above mentioned.In the first year, one-dimensionl TCPR(1,1) codes with the coding rate eta = 1/2, 2/3 and 3/4 have been developed and compared bit error rate(BER) characteristics with the ordinary recording system on NRZI code plus PR(1,1)ML method, Then we confirmed the supericrity of the former over the latter at the normalized recording density K = 2.4(i.e. the realizable highest density at that time).In the next year, it has been verified that TCPR(1,1) system can hold the priority on BER over TCPR(1, -1) system at the case K <greater than or equal> 1.2. We also started to investigate the possibility of introduction on two-dimensional technique to TCPIn the final year, several new robust codes partaking all of two-dimensional technique, MTR(maximum transition run) property and trellis function have been developed.