Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

International Business Machines Corporation

Western Digital Technologies, Inc.

Lsi Corporation

Avago Technologies General IP (singapore) Pte. Ltd.

Omnitier Storage, Inc.

University of Minnesota

Travis Roger Oenning

Richard Leo Galbraith

Weldon Mark Hanson

Evangelos Stavros Eleftheriou

Roy Daron Cideciyan

Thomas Mittelholzer

Bruce Alexander Wilson

Jonathan Darrel Coker

Ksenija Lakovic

Ajay Dholakia

Yuan Xing Lee

Mario Blaum

Luiz M Franca-Neto

Ivana Djurdjevic

Shaohua Yang

Zongwang Li

Martin Aureliano Hassner

Hideki Sawaguchi

Sharat Batra

Jongseung Park

Srinivasan Surendran

Ross Wilson

Satoshi Yamamoto

David James Stanek

Michael Joseph Ross

Todd Carter Truax

Balamurugan Anandan

George Mathew

Jeffrey Paul Grundvig

Richard Rauschmayer

Roger William Wood

David W Kelly

Jaekyun Moon

David Timothy Flynn

Fuminori Sai

Jeffrey A Gleason

Jason S Goldberg

Scott O'Brien

Jaydip Bhaumik

Kraig Bottemiller

Eric James Tree

A first string, having a first string value, that is associated with a sample set of material is received, wherein a second string, having a complementary value relative to the first string value, is also associated with the sample set of material. A determinative hash is generated using the first string value and a symmetric generator polynomial. A second hash, corresponding to the second string, is generated directly from the determinative hash. A canonized hash is generated using the determinative hash and the second hash. It is determined whether at least one of the first string or the second string is stored in string storage that is configured to store a plurality of strings, including by searching a hash table for the canonized hash; in the event it is determined that at least one of the first string or the second string is not stored in the string storage, at least one of the first string or the second string is stored in the string storage.

Reversible hash generators for pairs of complementary sequences

A first string, having a first string value, that is associated with a sample set of material is received where a second string, having a complementary value relative to the first string value, is also associated with the sample set of material. A reversible hash generator is used to generate a determinative hash using the first string value, where a second hash, corresponding to the second string, is able to be determined directly from the determinative hash and without the reversible hash generator processing the complementary value of the second string. It is determined whether at least one of the first string or the second string is stored in a memory using the determinative hash.

A system according to one embodiment includes a magnetic head having a plurality of sensors arranged to simultaneously read at least three immediately adjacent data tracks on a magnetic medium, wherein none of the sensors share more than one lead with any other of the sensors. Such embodiment may be implemented in a magnetic data storage system such as a disk drive system, which may include a magnetic head, a drive mechanism for passing a magnetic medium (e.g., hard disk) over the magnetic head, and a controller electrically coupled to the magnetic head.

Multi-track reader for improved signal to noise ratio

An apparatus for correcting crosstalk in an array reader magnetic recording system includes an array reader comprising a number of read heads operable to read data from a magnetic storage medium, a preamplifier configured to amplify the signals from the read heads, and a crosstalk correction circuit configured to reduce crosstalk between signals from the read heads.

Preamplifier crosstalk correction in array reader magnetic recording system

The present invention generally relates to a read head in a magnetic recording head. The read head utilizes two reader elements that are stacked in the down track direction within the same read gap to improve resolution and SNR by combining the signals from the two reader elements. The output waveform from each read element is asymmetric in the down track direction; however, by use of equalizer settings and waveform combining the algorithm in signal processing, the combined waveform has a similar or better resolution and higher SNR compared to a single read element in a smaller read gap.

Multiple readers for high resolution and SNR for high areal density application

An apparatus for measuring cross-talk in an array reader magnetic storage system includes an array reader with multiple read heads operable to read data from a magnetic storage medium, a first preamplifier connected to a first read head, a second preamplifier connected to a second read head, and a cross-talk measurement circuit connected to the first preamplifier and to the second preamplifier, operable to measure cross-talk between a first signal from the first read head and a second signal from the second read head.

Cross-talk measurement in array reader magnetic recording system

Systems, methods, devices, circuits for data processing, and more particularly to systems and methods for determining a down track distance between two or more read heads on a read/write head assembly.

Systems and methods for head position estimation

Disk drives are described in which blocks of data spanning multiple sectors are encoded into a plurality of codewords which are then divided into segments that are physically separated (distributed) on the disk surface over multiple sectors in a distributed codeword block so that the codewords have an improved worst case SNR in comparison to individual sectors. This results in more even SNR performance for each codeword, which improves the performance for portions of a track which have lower than the average SNR. Embodiments are described in which the distributed codeword blocks span across tracks.

Disk drive with distributed codeword blocks

A hard disk drive has disks with data sector preambles that allow for inter-track interference. The same data sector preamble is used for all data sectors in a track but the preamble in each track is different from the preamble in radially adjacent tracks. In a first embodiment each preamble includes a synchronization field (SF) and synchronization mark (SM) that are the same in each track but different from the SF and SM in radially adjacent tracks. Only two unique SFs and two unique SMs are required, with the two SFs and two SMs alternating in radially adjacent tracks. In a second embodiment the preambles are 'integrated', meaning that the preamble is a sequence of bits that does not include separate dedicated fields, like SF and SM. The preamble bit sequences are decoded using matched filters to provide bit synchronization and start-of-data information.

Disk drive with different data sector integrated preambles in adjacent data tracks

Disk drive with different synchronization fields and synchronization marks in the data sector preambles in adjacent data tracks

A method of enhancing read performance in array-reader hardware includes generating, by the array-reader hardware, a plurality of signals, according to data read from a magnetic disk, and canceling at least a portion of cross-talk in the plurality of signals to generate a plurality of corrected signals.

Cross-talk compensation in array based reader systems

A receiver utilizes a plurality of read elements, each generating a read-back signal in response to a data track positioned beneath the read element. The plurality of read-back signals are each provided to at least one space-time interference cancellation filter, which generates a filtered output that maximizes a signal associated with one of the plurality of data tracks. The filtered output is provided to a one-dimensional Viterbi detector, which is configured to generate in response an output representative of a data sequence written to one of the plurality of data tracks.

Low complexity inter-track interference cancellation receiver for magnetic multiple-input, multiple-output (MIMO) channel

A method, apparatus, and system are provided for implementing magnetic defect location detection on-the-fly for hard disk drives. A magnetic media readback signal of a hard disk drive is demodulated to generate phase modulation (PM) and amplitude modulation (AM) signals. A new coordinate plane defined by a combined phase modulation (PM) and amplitude modulation (AM) phasor-defect detector calculation function used to locate magnetic defects on-the-fly.

Implementing combined phase and amplitude magnetic defect detection on-the-fly

A method, apparatus, and system are provided for implementing magnetic defect classification using phase modulation for hard disk drives. A magnetic media readback signal of a hard disk drive is processed to identify predefined phase modulation (PM) characteristics to implement magnetic defect classification of magnetic media bump and pit defects.

Implementing magnetic defect classification using phase modulation

Growing community of inventors

Rochester, MN, United States of America

Travis Roger Oenning