We manufactured a high-frequency wobbled groove disk, and examined reading/writing of an magneto-optical signal by using a clock generated from the wobbled groove. We also measured clock jitter and bit error rate. The results were clock jitter of under 2.5ns, and a bit error rate almost equal to that of a self-clock. The wobbled groove clock method is therefore effective for higher density recording.
We have investigated the performance of a high density, read-only type, optical disc system by computer simulation. This optical disc system records 3 levels of digital data on each pit edge by a multi-level pit edge recording method, and reads 4 pit edges at the same time by a 2 dimensional Partial Response Maximum Likelihood (PRML) reproduction method. The simulation result showed that the recording density of the system reached up to twice as high as that of the DVD while with the same optical pickup of a DVD player. The result also showed that a write pre-compensation technique and a Viterbi decoding method were effective for improving the performance.
Various kinds of media, such as VTR tape, hard disk, optical disk were used for in stages for acquiring, editing, and archiving. However, an appearing of an optical-disk-recorder available for acquiring will settle the problem of difficulties for media-arranging or media-relaying. Therefore, we studied a recording-format for rapid accessing for archives using optical disk recorder.
In the age of digital multimedia, demand is bound to rise for television Home Servers that automatically record a viewer's favorite programs so that he/she can watch them at any time. We have developed an experimental. Home Server on which a recorded HDTV program can be played back while recording another digital HDTV program. Using a new HSMS (hierarchical storage management system) we proposed, it was able to store HDTV programs for 4 hours and was as small as thickness of flat displays. This paper describes the outline of the experimental system and its element technologies.