Seagate Technology Incorporated

Carnegie Mellon University

Erozan Mehmet Kurtas

Xueshi Yang

Mehmet Faith Erden

Bane Vasic

Mehmet Fatih Erden

Alexander Kuznetsov

Jongseung Park

Ivana Djurdjevic

Mark David Bedillion

Cenk Argon

Darren William Karns

Mark Edward Re

John Robert Barry

Piya Kovintavewat

Mustafa Nazmi Kaynak

Rohit Negi

Xun Zhang

A parallel channel timing recovery circuit. The parallel timing recovery circuit comprises multiple prefilters receiving parallel channel outputs and providing prefilter outputs. Multiple sampling filters receive the prefilter outputs and provide multiple discrete time signal samples. A self-timing circuit has multiple inputs receiving the multiple discrete time signal samples. The self-timing circuit provides a sampling control output to the sampling filters. The sampling control output is based on a composite of the multiple discrete time signal samples. Each of the sampling filters generates a discrete time signal sample based on the sampling control output and the prefilter outputs.

Timing recovery in a parallel channel communication system

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.

Communication channel with Reed-Solomon encoding and single parity check

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.

System and method for drive-side guarantee of quality of service and for extending the lifetime of storage devices

A method of reading a data block from a sector of a recording media is described. The data block from the sector of the recording channel is decoded with an ECC decoder (first trial). The data block is re-decoded (second trial) using an adjusted timing recovery block that is adjusted based on the decoded data block, if the number of errors exceeded an error correction capability of the ECC decoder on the first trial. In one embodiment, the data block is reread from the same sector of the recording channel using the adjusted timing recovery block that is adjusted based on the re-decoded data block. The data block is subsequently jointly decoded with the waveforms obtained from the second trial by a possibly modified sequence detector, if the number of errors exceeded the error correction capability of the ECC decoder during the second trial.

Retrial and reread methods and apparatus for recording channels

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.

Synchronization for data communication

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.

Method and apparatus for providing iterative timing recovery

A system for pattern dependent equalization has an equalizer bank and a detector. The equalizer bank has a plurality of equalizers, which are each tuned to a selected data pattern. The detector may be a standard sequence detector or a modified Viterbi detector, which calculates the branch metric using a pattern dependent equalized output and a pattern-dependent target. A method of decoding data uses a pattern dependent equalizer bank. The pattern dependent equalizer bank processes a segment of a bit sequence to produce an equalized pattern-dependent output for each equalizer in parallel. The detector then detects the bit sequence using the branch metric calculation to select the smallest accumulated path metric.

Pattern-dependent equalization and detection

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.

Method and apparatus for interative noise whitening with causal and anti-causal prediction filters

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. The data detector is adapted to generate an output based on the distance calculator output.

[object Object]

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.

System and method for iterative decoding of Reed-Muller codes

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.

Correcting radial incoherence in servo track sensing

A data storage system in which multiple readback signals are resolved is provided. The data storage system includes a data storage medium configured to store servo marks and data marks. The data storage medium has tracks that are divided into sectors. An array of heads is configured to interact with the data storage medium. A demodulation circuit receives servo signals obtained by at least some heads of the array of heads and computes a resultant servo signal, which is used to adjust a position of the array of heads over the storage medium.

Positioning of a head array over a data storage medium

A method of generating low density parity check codes for encoding data includes constructing a parity check matrix H from balanced incomplete block design (BIBD) in which a plurality B-sets which define the matrix have no more than one intersection point. The parity bits are then generated as a function of the constructed parity check matrix H.

Method and coding apparatus using low density parity check codes for data storage or data transmission

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.

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Pittsburgh, PA, United States of America

Erozan Mehmet Kurtas