Abstract: An iterative decoding system for intersymbol interference (ISI) channels has a module for extracting bit reliabilities from a partial response (PR) channel, an iterative decoder, and a module for updating the bit reliabilities. A transmitter parses a data sequence into blocks that are encoded to generate a sequence of codewords. By encoding, a correlation among the bits of each codeword output to the PR channel is created. A maximum likelihood sequence detector (MLSD) in the receiver produces estimates of transmitted bits from samples of the output from the PR channel. The MLSD detector has a priori knowledge of typical error events that can occur during transmission through the channel. Along with the bit estimates, at each time instant the MLSD detector generates set of error event likelihoods.

Abstract: The present invention is a method and system for generating soft outputs by taking advantage of the fact that, in PR channels, there exists a set of error event sequences that occurs more often than others. This results in a soft output extractor with significantly lower complexity than the prior art SOVA system. Minimum distance error event sequences are identified and soft information or bit reliabilities are extracted from the PR channel based on the identified sequences. The soft information is then used by an iterative error control decoder correct errors more efficiently.

Abstract: An iterative decoding system for intersymbol interference (ISI) channels has a module for extracting bit reliabilities from a partial response (PR) channel, an iterative decoder, and a module for updating the bit reliabilities. A transmitter parses a data sequence into blocks that are encoded to generate a sequence of codewords. By encoding, a correlation among the bits of each codeword output to the PR channel is created. A maximum likelihood sequence detector (MLSD) in the receiver produces estimates of transmitted bits from samples of the output from the PR channel. The MLSD detector has a priori knowledge of typical error events that can occur during transmission through the channel. Along with the bit estimates, at each time instant the MLSD detector generates set of error event likelihoods.

Abstract: The invention provides a method of proving that a CD is an authorized original by utilizing a unique catalog code that is stored in a sub channel data stream on the CD that is derived using digital signature techniques. The inputs for the unique catalog code are derived from a digital signature algorithm and include, in the case of audio CD, each song's ISRC number, a bar code or unique identifier of the CD and the audio data content. To verify that the CD is not a copy, the original digital signature algorithm used at the time of recording to create the unique catalog code is applied to the audio data and ISRC codes recorded on the disc to derive a catalog code. An authorized original CD will have the same catalog code value stored in the subchannel as the catalog code derived from the digital signature algorithm. If the catalog codes do not match, the disc is determined to be an illegal copy.

Abstract: An optical recording medium comprising a first substrate with a center mounting hole and having top and bottom surfaces. At least one surface of the substrate is a prerecorded area wherein user data is provided and adapted to be read in an optical recording medium reader device. Over at least a portion of the substrate that can be read by the device is a photosensitive layer comprising a photosensitive material. When the photosensitive material is exposed to a predefined wavelength of light over a predetermined period of time the optical property of at least a portion of the material permanently changes. This change occurs after each copy of the prerecorded area is made. Thereby, the optical recording medium limits the authorized copies of the prerecorded area to a predetermined number.