| 摘要 |
In a recording method, an optical disk, such as a magneto-optical disk, has data recorded in a spiral track or in concentric tracks which contain a reference pattern repeated in each of n blocks. The reference pattern of a block exhibits distinct amplitude levels from which are derived plural threshold levels that are used during a playback operation of a reproducing method and apparatus to detect reproduced data values. The levels of the reference pattern in each of the n blocks are sampled and used to produce at least two (eg. higher and lower) threshold levels against which the data reproduced from the disk is compared to detect the values of such data. <IMAGE> |
