TSUZUKI Shinji EHIME UNIVERSITY,FACULTY OF ENGINEERING,ASSISTANT, 工学部, 助手 (60236924)
YAMADA Yoshio EHIME UNIVERSITY,FACULTY OF ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (00110833)
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,
(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 TCP
In the final year, several new robust codes partaking all of two-dimensional technique, MTR(maximum transition run) property and trellis function have been developed.