Abstract: A method for synchronizing newly recorded data with previously recorded data. The method is implemented within a disk-based data storage system. A first difference between a wobble reference signal and previously recorded data is measured. Test data is written on a test track to measure a second difference between the wobble reference signal and the test data. The test data is written synchronously with a write clock. An offset value is determined by comparing the first difference and the second difference. New data is then written using the write clock and the offset value such that the new data is synchronized with the old data. To determine the offset value, the test data can be written to the test track with a write clock calibration delay set to zero, the test data can then be read from the test track and the first difference can be subtracted from the second difference to determine the offset value for the write clock calibration delay.

Abstract: A data decoder for decoding digital data in a high frequency signal in an optical storage device. A carrier signal derived from the high frequency passed through a zonal bandpass filter and a limiter is multiplied by the high frequency signal passed through a high pass filter. The resulting product is filtered and passed through a comparator forming a digital data stream.

Abstract: An optical disk and compatible optical disk drive enabling erasable (rewritable) optical disks to have the same format and capacity as read-only or (recordable) write-once optical disks. A reference clock track and optional additional prerecorded phase synchronization patters are provided to enable writing of any random sector with frequency and phase matching of a random sector to the preceding and following sectors. The reference clock track and other phase synchronization patterns eliminate the need for preambles and extra space for speed variation. In a first embodiment, a disk has multiple layers, with at least one rewritable data layer and at least one reference layer. A spiral track on a surface of the reference layer has prerecorded patterns to be used for clocking. In a variation of first embodiment, the reference layer is also used for radial tracking control, eliminated the need for predefined tracks in the rewritable data layers.

Abstract: An optical disk and compatible optical disk drive enabling erasable (rewritable) optical disks to have the same format and capacity as read-only or (recordable) write-once optical disks. A reference clock track and optional additional prerecorded phase synchronization patters are provided to enable writing of any random sector with frequency and phase matching of a random sector to the preceding and following sectors. The reference clock track and other phase synchronization patterns eliminate the need for preambles and extra space for speed variation. In a first embodiment, a disk has multiple layers, with at least one rewritable data layer and at least one reference layer. A spiral track on a surface of the reference layer has prerecorded patterns to be used for clocking. In a variation of first embodiment, the reference layer is also used for radial tracking control, eliminated the need for predefined tracks in the rewritable data layers.

Abstract: Decryption or descrambling information or other data modification information is encoded into patterns of merge bits for primary information. The decoded information is used to decrypt, descramble or otherwise modify the primary information. In another embodiment, a sequence of symbols is added to original data, the sequence of symbols selected to encode into channel bits having a large accumulated digital sum variance. In another embodiment, a single symbol in the sequence of symbols is replaced after error correction symbols have been added. In another embodiment, decryption or descrambling information or other data modification information is encoded into the sign of the digital sum variance of each blocked row of data.

Abstract: A method of inhibiting copying of digital data. In a first embodiment, a sequence of symbols is added to original data, the sequence of symbols selected to encode into channel bits having a large accumulated digital sum variance. The sequence of symbols is then encoded by a special encoder that generates special channel bits that don't have a large accumulated digital sum variance. The special channel bits may be unambiguously decoded, but the resulting decoded symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a second embodiment, a single symbol in the sequence of symbols is replaced after error correction symbols have been added. The sequence of symbols with one substituted symbol is encoded into channel bits that don't have a large accumulated digital sum variance.

Abstract: An optical disk and compatible optical disk drive enabling erasable (rewritable) optical disks to have the same format and capacity as read-only or (recordable) write-once optical disks. A reference clock track and optional additional prerecorded phase synchronization patterns are provided to enable writing of any random sector with frequency and phase matching of a random sector to the preceding and following sectors. The reference clock track and other phase synchronization patterns eliminate the need for preambles and extra space for speed variation. In a first embodiment, a disk has multiple layers, with at least one rewritable data layer and at least one reference layer. A spiral track on a surface of the reference layer has prerecorded patterns to be used for clocking. In a variation of first embodiment, the reference layer is also used for radial tracking control, eliminating the need for predefined tracks in the rewritable data layers.

Abstract: A phase change overwrite system that reduces the phase change material flow which results from the repeated overwrites of the same data on the media. Two techniques can be used to solve the overwrite degradation problem. The first is to exploit the fact that a given data sequence can be represented by multiple bit patterns. This choice in bit patterns is primarily for use in reducing the low frequency content of the bit pattern. However, some of the choice available may be used for other purposes, such as ensuring the same bit pattern is not always used. The second technique is to vary the point in the bit pattern at which writing begins. This is possible in a ROM type format because the new data are written in exactly the same location as the old data. Therefore, if the old data are exactly the same as the new data, it is optional whether or not to overwrite the old data. Note that typically the header information for old and new data is the same.

Abstract: A method and apparatus for embedding and retrieving an additional data bitstream in an encoded data stream, such as MPEG. The embedded data is processed and a choice parameter in the header portion of the encoded data stream is varied according to the embedded information bit pattern. Optimization of the encoded data stream is not significantly affected. The embedded information is robust in that the encoded data stream would need to be decoded and re-encoded in order to change a bit of the embedded information. As relevant portions of the header are not scrambled to facilitate searching and navigation through the encoded data stream, the embedded data can generally be retrieved even when the encoded data stream is scrambled.

Abstract: A data encryption/decryption system encrypts data and its associated redundancy bytes while retaining the error correction capabilities of the original data. The error correction function can then be removed, for example, from a storage drive and performed by, e.g. a host processor or a other entity. The storage drive reads the raw data, including error correction codes, from the media and encrypts the data by exclusive OR-ing each error correction code (ECC) block with a new ECC block which was generated using random data and the same ECC scheme. Error correction of the new data block can be performed in the host processor or other entity without exposing the original data. The error correction is valid for any errors that occurred in the original raw data because the ECC redundancy bytes of the random data block were created using the same ECC generator as was used with the original data.

Abstract: Frequently only a portion of the data within an error correction data block is required to be changed or overwritten. For example in optical data storage on DVD type discs, an error correction block contains 32K bytes of user data, however, a computer system typically operates on 2K byte sectors and therefore frequently does not involve the full 32K byte block. In these circumstances the old data block must be read, error corrected, the new data combined with the old and new error correction redundancy bytes calculated. This invention is a method and apparatus of improving access time when only a portion of the data in an error correction data block is modified. The contributions to the redundancy bytes in the codewords, due to the old data to be modified and the new data to be written, are calculated.

Abstract: A method of inhibiting copying of digital data. In a first embodiment, a sequence of symbols is added to original data, the sequence of symbols selected to encode into channel bits having a large accumulated digital sum variance. The sequence of symbols is then encoded by a special encoder that generates special channel bits that don't have a large accumulated digital sum variance. The special channel bits may be unambiguously decoded, but the resulting decoded symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a second embodiment, a single symbol in the sequence of symbols is replaced after error correction symbols have been added. The sequence of symbols with one substituted symbol is encoded into channel bits that don't have a large accumulated digital sum variance.

Abstract: A method of inhibiting copying of digital data. In a first embodiment, a sequence of symbols is added to original data, the sequence of symbols selected to encode into channel bits having a large accumulated digital sum variance. The sequence of symbols is then encoded by a special encoder that generates special channel bits that don't have a large accumulated digital sum variance. The special channel bits may be unambiguously decoded, but the resulting decoded symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a second embodiment, a single symbol in the sequence of symbols is replaced after error correction symbols have been added. The sequence of symbols with one substituted symbol is encoded into channel bits that don't have a large accumulated digital sum variance.