International Business Machines Corporation

Globalfoundries Inc.

Awemane Ltd.

Sedat Oelcer

Robert Allan Hutchins

Evangelos Stavros Eleftheriou

Robert Allen Hutchins

Thomas Mittelholzer

Roy Daron Cideciyan

Jens Jelitto

Katherine Tyldesley Blinick

Glen Alan Jaquette

Giovanni Cherubini

Larry LeeRoy Tretter

Jacob Lee Dahle

Gordon Taylor Davis

Malcolm Scott Ware

Jeffrey Haskell Derby

Ernest Stewart Gale

Gottfried Ungerboeck

Eric Rolf Christensen

Nhan Xuan Bui

Richard Leo Galbraith

Ajay Dholakia

David Berman

Constantin Michael Melas

Mark Allan Taylor

Hisato Matsuo

Wolfgang H Schott

Francois Bernard Dolivo

Evangelos S Eleftherion

Robert Allen Hutchins, Iii

Jon Coker

Rick Galbraith

Thomas Mittleholzer

Andreas Rungeler

In one embodiment, a system includes a processor, and logic integrated with the processor, executable by the processor, or integrated with and executable by the processor. The logic is configured to cause the processor to write, by the processor, data to a storage medium of a data storage system using a partial reverse concatenated modulation code. The partial reverse concatenated modulation code comprises encoding the data by applying a C2 encoding scheme prior to encoding the data by applying one or more modulation encoding schemes, followed by encoding the data by applying a C1 encoding scheme subsequent to the encoding of the data with the one or more modulation encoding schemes.

Partial reverse concatenation for data storage devices using composite codes

In one embodiment, a computer program product includes a computer readable storage medium having program instructions embodied therewith. The computer readable storage medium is not a transitory signal per se. The embodied program instructions are readable/executable by a processor to cause the processor to write, by the processor, data to a storage medium of a data storage system using a partial reverse concatenated modulation code. The partial reverse concatenated modulation code includes encoding the data by applying a C2 encoding scheme prior to encoding the data by applying one or more modulation encoding schemes, followed by encoding the data by applying a C1 encoding scheme subsequent to the encoding of the data with the one or more modulation encoding schemes. Other computer program products for writing data to a storage medium of a data storage system using a partial reverse concatenated modulation code are presented according to more embodiments.

In one embodiment, a method includes writing data to a storage medium, via a write channel, by applying a partial reverse concatenated modulation code to the data prior to storing encoded data to the storage medium. The applying the partial reverse concatenated modulation code to the data includes application of a C2 encoding scheme to the data to produce C2-encoded data prior to application of one or more modulation encoding schemes to the C2-encoded data to produce modulated data, followed by application of a C1 encoding scheme to the modulated data subsequent to the application of the one or more modulation encoding schemes to produce the encoded data.

According to one embodiment, a method for processing data includes directing first data through a first FIR gain module in response to a determination that the first data is being read from a magnetic tape medium in an asynchronous mode to control FIR gain of the first data. The method also includes directing second data through a second FIR gain module in response to a determination that the second data is being read from the magnetic tape medium in a synchronous mode to control FIR gain of the second data. Other systems and methods for processing data using dynamic gain control with adaptive equalizers are presented according to more embodiments.

Dynamic gain control for use with adaptive equalizers

In one embodiment, a system for cycle-slip resilient iterative read channel operation includes a processor and logic integrated with and/or executable by the processor. The logic is configured to, in an iterative process until a maximum number of iterations has been reached or a valid codeword is produced, execute cycle-slip detection on signal samples to detect one or more cycle-slip events. Also, the logic is configured to selectively alter a timing estimate driving a phase-locked loop (PLL) during any time interval determined to experience a cycle slip in a first pass as indicated by one or more cycle-slip pointers. Additionally, the logic is configured to generate a set of decisions provided by a detector and generate a set of decisions provided by a decoder. Moreover, the logic is configured to output decoding information relating to the signal samples in response to a decoding algorithm producing a valid codeword.

Cycle-slip resilient iterative data storage read channel architecture

In one embodiment, a data storage system includes a write channel for writing data to a storage medium, the write channel configured to utilize a partial reverse concatenated modulation code. The write channel includes logic adapted for encoding data sets using a Cencoding scheme, logic adapted for adding a header to each subunit of the data sets, logic adapted for encoding the headers of the data sets with a first modulation encoding scheme, logic adapted for encoding data portions of the data sets with a second modulation encoding scheme, logic adapted for encoding portions of the one or more C-encoded data sets using a Cencoding scheme, logic adapted for combining the C-encoded portions with the modulation-encoded headers of the C-encoded data sets using a multiplexer, and logic adapted for writing the one or more combined C- and C-encoded data sets to data tracks.

According to one embodiment, a magnetic tape drive includes a controller configured to direct first data through a first finite impulse response (FIR) gain module in response to a determination that the first data is being read from a magnetic tape medium in an asynchronous mode to control FIR gain of the first data. The controller is also configured to direct second data through a second FIR gain module in response to a determination that the second data is being read from the magnetic tape medium in a synchronous mode to control FIR gain of the second data. A FIR gain value of the second FIR gain module is automatically controlled. Other systems for dynamic gain control with adaptive equalizers are described according to more embodiments.

In one embodiment, a tape drive system includes a soft detector having logic configured to execute a first forward loop of a detection algorithm on a first block of signal samples during a first time interval, execute a first reverse loop of the detection algorithm on the first block of signal samples during a second time interval, execute a second reverse loop of the detection algorithm on the first block of signal samples during a fifth time interval, and execute a second forward loop of the detection algorithm on the first block of signal samples during a fourth time interval using second soft information. Other tape drive systems and computer program products for decoding data are presented in more embodiments.

Combined soft detection/soft decoding in tape drive storage channels

According to one embodiment, a computer program product for dropout detection in a read channel includes a computer readable storage medium having program code embodied therewith, the embedded program code being readable and/or executable by a processor to execute dropout detection on a block of signal samples to detect one or more dropout events employing a set of decisions provided by a detector executing a detection algorithm, determine an approximate location for each of the one or more detected dropout events, statistically characterize the one or more detected dropout events to calculate one or more dropout profiles, and selectively filter the block of signal samples during a duration of each of the detected dropout events. Other computer program products, systems, and methods for detecting dropouts are presented in more embodiments.

Iterative data storage read channel architecture having dropout mitigation

According to one embodiment, a system for processing data includes a controller configured to: receive data read from a magnetic storage medium, apply a finite impulse response (FIR) filter to the data to obtain equalized data, and direct the equalized data through either a first FIR gain module or a second FIR gain module to control FIR gain of the equalized data, wherein the first FIR gain module is utilized when reading data in an asynchronous mode, and wherein the second FIR gain module is utilized when reading data in a synchronous mode and a FIR gain value of the second FIR gain module is automatically controlled. Other systems and methods for processing data using dynamic gain control with adaptive equalizers are presented according to more embodiments.

In one embodiment, a computer program product for iterative read channel operation has program instructions embodied therewith that are executable by a controller to cause the controller to: in an iterative process until a maximum number of iterations has been reached or a valid codeword is produced: execute one or more digital front-end (DFE) functions on a plurality of signal samples employing the set of decisions provided by a decoder; execute a detection algorithm on the signal samples using a detector employing the set of decisions provided by the decoder to regenerate the set of decisions provided by a detector; execute a decoding algorithm of an error correcting code (ECC) using the set of decisions provided by the detector to regenerate the set of decisions provided by the decoder; and output decoding information relating to the signal samples when the decoding algorithm produces a valid codeword.

Iterative data storage read channel architecture

According to one embodiment, a magnetic medium's readback signal samples are processed iteratively to provide a slip-resistant read channel by feeding the decoder output decisions back to the read channel front end where they are used to drive the decision-aided digital signal processing functions and control loops. Since data decisions provided by the decoder are typically more reliable than those provided by the detector, a significant performance improvement is obtained. A more reliable operation of the digital front-end signal processing functions in turn allows improvements to the reliability of the decoded data. Usage of Error Correcting Code (ECC) schemes that are soft decodable makes the read channel technique, described according to various embodiments herein, particularly efficient.

In one embodiment, a method includes executing a first forward loop of a detection algorithm on a block of signal samples during a first time interval, executing a first reverse loop of the detection algorithm on the block during a second time interval to produce first soft information, executing a decoding algorithm on the block during a third time interval using the first soft information to produce second soft information, executing a second forward loop of the detection algorithm on the block during a fourth time interval using the second soft information, executing a second reverse loop of the detection algorithm on the block during a fifth time interval to produce third soft information, executing the decoding algorithm on the block during a sixth time interval using the third soft information to produce a decoded block of signal samples, and outputting the decoded block of signal samples.

In one embodiment, a tape drive system includes a write channel for writing data to a magnetic tape, the write channel utilizing a rate-(232/234) reverse concatenated modulation code. The write channel includes logic adapted for receiving a data stream comprising one or more data sets, logic adapted for separating each data set into a plurality of sub data sets, logic adapted for encoding each sub data set with a C2 encoding, logic adapted for encoding each C2-encoded sub data set with a modulation code, logic adapted for encoding each modulated sub data set with a C1 encoding, and logic adapted for simultaneously writing the encoded modulated sub data sets to data tracks of the magnetic tape. Other systems for writing data to a magnetic tape utilizing a rate-(232/234) reverse concatenated modulation code are described according to various other embodiments.

Data format using an efficient reverse concatenated modulation code for magnetic tape recording

In one embodiment, a method for writing data to a magnetic tape utilizing a rate-(232/234) reverse concatenated modulation code includes receiving a data stream comprising one or more data sets, separating each data set into a plurality of sub data sets, encoding each sub data set with a C2 encoding, encoding each C2-encoded sub data set with the modulation code, encoding each modulated sub data set with a C1 encoding, and simultaneously writing the encoded modulated sub data sets to data tracks of the magnetic tape. Other methods for writing data to a magnetic tape utilizing a rate-(232/234) reverse concatenated modulation code are described according to various other embodiments.

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Kilchberg, Switzerland

Sedat Oelcer