Abstract: A communication channel including Reed-Solomon (RS) and single-parity-check (SPC) encoding/decoding. Multiple RS codewords are combined and then SPC encoded into an RS/SPC array. A soft-input soft-output (SISO) channel detector detects the RS/SPC encoded bits and provides soft (reliability) information on these bits. A combined RS and SPC error correction block provides a recovered user output. An iterative soft input decoding algorithm combines RS and SPC error correction.

Abstract: Timing recovery and synchronization for data communication is utilized. A pilot sequence of signals can be selected to improve recovery of a phase offset and a frequency offset in a communication system. Sampling instances can further be adjusted based on pilot sequences within a user data portion.

Abstract: A method includes the steps of receiving a signal indicative of data bits, and performing per survivor processing-iterative timing recovery (PSP-ITR) on the received signal to generate probabilities of the data bits. To perform PSP-ITR on the received signal, the signal can be processed using a per survivor processing-soft decision algorithm (PSP-SDA) which jointly performs timing recovery and equalization in accordance with embodiments of the present invention. The soft decision algorithm (SDA) can be, for example, a Bahl, Cocke, Jelinek, and Raviv (BCJR) algorithm or a Soft Output Viterbi Algorithm (SOVA) modified in accordance with the concepts of the present invention such that it is configured to implement per survivor processing (PSP) to jointly perform timing recovery and equalization.

Abstract: A channel detector includes a belief propagation detector that is coupled to a channel and adapted to receive a channel output and to generate tentative bit decisions based in part on the channel output. The channel detector further includes a causal and anti-causal channel output module coupled to the belief propagation detector and adapted to generate causal and anti-causal channel outputs based on the tentative bit decisions. The channel detector also includes a noise prediction module coupled to the causal and anti-causal channel output module and adapted to predict noise samples based on a difference between the channel output and the causal and anti-causal channel outputs. Further, the channel detector includes a noise prediction module adapted to whiten the channel output with the predicted noise samples and to return the whitened channel output to the belief propagation detector to generate new tentative bit decisions.

Abstract: A channel detector has an anchor points inserter, a desired signal calculator, a distance calculator and a data detector. The anchor points inserter is adapted to choose values of expected transition locations for transition shifts within a received signal and to insert anchor points corresponding to the chosen values within a bit detection interval. The desired signal calculator is coupled to the anchor points inserter and is adapted to estimate desired signals corresponding to transition location information from the anchor points inserter. The distance calculator is coupled to the desired signal calculator and is adapted to generate a distance calculator output based on distances between the received signal and each of the desired signals. The data detector is coupled to the distance calculator and is adapted to identify a bit sequence corresponding to a desired signal having a minimum distance from the received signal.

Abstract: A storage device has a storage medium, a plurality of read-write mechanisms, a quality monitoring and book-keeping unit and a scheduling unit. The plurality of read-write mechanisms is coupled to the storage medium. The quality monitoring and book-keeping unit is coupled to the plurality of read-write mechanisms and is adapted to monitor at least one performance parameter associated with each read-write mechanism during operation. The scheduling unit is coupled to the quality monitoring and book-keeping unit. The scheduling unit is adapted to rank each of the plurality of read-write mechanisms according to the at least one performance parameter and to responsively schedule use of a read-write mechanism according to its rank.

Abstract: Timing recovery and synchronization for data communication is utilized. A pilot sequence of signals can be selected to improve recovery of a phase offset and a frequency offset in a communication system. Sampling instances can further be adjusted based on pilot sequences within a user data portion.

Abstract: A system for soft-decoding of Reed-Muller coded information has one or more rows of decoding blocks, each decoding block having a soft-output device and a Reed-Muller message passing device. A first soft-output device of a first decoding block processes a coded signal and a zero value probability vector. Each subsequent soft-output device processes the coded information and a non-zero value probability vector. The system for soft-decoding Reed-Muller coded information decodes a code-bit reliability vector from a soft-output device to generate an updated codeword reliability vector, which is used by a next decoding block in a sequence of decoding blocks to reprocess the coded information using the updated reliability vector. The reliability vector is updated through processing in each decoding block to optimize the reliability vector for extraction of the transmitted information from the received information.

Abstract: A communication channel including Reed-Solomon (RS) and single-parity-check (SPC) encoding/decoding. Multiple RS codewords are combined and then SPC encoded into an RS/SPC array. A soft-input soft-output (SISO) channel detector detects the RS/SPC encoded bits and provides soft (reliability) information on these bits. A combined RS and SPC error correction block provides a recovered user output. An iterative soft input decoding algorithm combines RS and SPC error correction.

Abstract: A servo track sensing system receives equalized servo data from a servo demodulator and corrects for radial incoherence in the servo data. The system has a radial incoherence estimator that receives the equalized servo data and provides a radial incoherence estimate. A sequence detector receives the equalized servo data and the radial incoherence estimate, and provides a sequence detector output. A correlator receives the sequence detector output and provides correlator output data. The correlator output data has a reduced level of errors due to radial incoherence.

Abstract: The Turbo decoding architecture has a first soft-input soft-output (SISO) device having a complex trellis structure and a Turbo decoder loop with a second SISO device having a simpler trellis structure. Coded information from a channel is processed by the first SISO device to generate a soft-output based on the coded information. The soft-output is then processed in an iterative loop using the second SISO device. The second SISO device interacts with a decoder device to produce a value representative of the transmitted information.

Abstract: The present invention provides a novel method and apparatus for decoding digital information transmitted through the communication channel or recorded on a recording medium. The method and apparatus are preferably applied in the systems where data is encoded using regular LDPC codes with parity check matrices composed from circulants (a matrix is called a circulant if all its column or row are cyclic shifts each other).

Abstract: The Turbo decoding architecture has a first soft-input soft-output (SISO) device having a complex trellis structure and a Turbo decoder loop with a second SISO device having a simpler trellis structure. Coded information from a channel is processed by the first SISO device to generate a soft-output based on the coded information. The soft-output is then processed in an iterative loop using the second SISO device. The second SISO device interacts with a decoder device to produce a value representative of the transmitted information.

Abstract: A system for soft-decoding of Reed-Muller coded information has one or more rows of decoding blocks, each decoding block having a soft-output device and a Reed-Muller message passing device. A first soft-output device of a first decoding block processes a coded signal and a zero value probability vector. Each subsequent soft-output device processes the coded information and a non-zero value probability vector. The system for soft-decoding Reed-Muller coded information decodes a code-bit reliability vector from a soft-output device to generate an updated codeword reliability vector, which is used by a next decoding block in a sequence of decoding blocks to reprocess the coded information using the updated reliability vector. The reliability vector is updated through processing in each decoding block to optimize the reliability vector for extraction of the transmitted information from the received information.

Abstract: A method of preprocessing low frequency components of a perpendicular read-back signal in a data storage system in order to reduce low frequency noise includes introducing a dominant known perturbation, to the perpendicular read-back signal, which masks the effects of other low frequency noise sources and leaves the read-back signal with one dominant low frequency noise component. The method then further includes removing the dominant known perturbation from the read-back signal to recover low frequency portions of the read-back signal in order to determine values of bits read from a storage medium. A perpendicular recording data storage system configured to implement the method is also disclosed.

Abstract: A method of preprocessing low frequency components of a perpendicular read-back signal in a data storage system in order to reduce low frequency noise includes introducing a dominant known perturbation, to the perpendicular read-back signal, which masks the effects of other low frequency noise sources and leaves the read-back signal with one dominant low frequency noise component. The method then further includes removing the dominant known perturbation from the read-back signal to recover low frequency portions of the read-back signal in order to determine values of bits read from a storage medium. A perpendicular recording data storage system configured to implement the method is also disclosed.