Abstract: Method for correcting the length of marks and lands representing information taken from an optical disk is disclosed. The method includes digitizing amplified analog data having marks and lands played back from an optical disk and providing a data synchronization clock by using a phase lock loop (PLL). The method further includes providing an adjustment to a threshold signal level based upon the difference in timing position in mark and land edge marks with reference to the data synchronization clock and changing the data mark and land lengths with reference to the adjusted threshold signal.

Abstract: A method for detecting and processing synchronization marks extracted from a prerecorded wobbled groove formed in a compact disk in order to produce pseudo-sync signals using a high frequency phase locked loop servoing to the disk speed to generate the signals.

Abstract: A method for detecting and processing ATIP information extracted from a prerecorded wobbled groove formed in a compact disk is disclosed. The prerecorded wobbled groove has a plurality of blocks of information. The method includes extracting an FM signal from the wobbled groove and providing a high frequency phase-lock loop which responds to the extracted FM signal to produce a high frequency clock. The method further includes converting such FM signal into biphase data by sampling and latching the FM ATIP signal from the wobbled groove; and digitally comparing a predetermined count value to a count value derived from the high frequency clock and the FM signal. It further includes extracting a clock signal from a digital phase-lock loop responsive to the biphase data; and providing an ATIP decoder which in response to the biphase data, biphase clock, and high frequency clock signal provides sync detection and address information.

Abstract: A method and apparatus for detecting and processing synchronization marks extracted from a prerecorded wobbled groove formed in a compact disk in order to produce pseudo-sync signals.

Abstract: In an information-bearing disk having, along concentric record tracks, pre-written equally spaced tracking pads which may or may not be aligned radially from one track to another, circuitry serves for improving the response time of a disk drive mechanism during a track-jump operation, i.e. when a read/write transducer head moves radially from one record track to any other track. The circuitry includes a phase-locked loop (PLL), coupled to the transducer head and responsive to a pulsed signal corresponding to the frequency at which the tracking pads sweep past the head, and thereby the actual speed of the disk, for producing an adjustable clock signal which controls the rate at which user data is transferred to or from track segments between adjacent tracking pads.

Abstract: An information-bearing record medium (magnetic tape, disk, or an equivalent thereof) includes a stream of binary bits in which a binary 1 bit is normally represented by a signal transition at the middle of its corresponding bit cell and a binary 0 bit is normally represented by a signal transition at the trailing edge of its corresponding bit cell so long as the immediately following bit cell contains a binary 0 bit, whereby the spacing between successive normal signal transitions is at least one bit cell and is no greater than two bit cells. The binary bit stream includes an address mark byte, for identifying a future substream of data bits, defined by a unique pattern of signal transition having at least one normal signal transition missing, whereby at least one pair of successive signal transitions is separated by more than two bit cells and less than four bit cells.