Patent application number | Description | Published |
20080235556 | REVERSE CONCATENATION FOR PRODUCT CODES - A system is provided to encode data for recording onto media whereby modulation and linear constraints from a concatenated code or product code are imposed. A first array of unencoded user data is generated. Each row is modulation encoded to enforce a first modulation constraint; the array is transformed into a second array which is transformed into a third array having predetermined empty locations in each column interleaved with the modulated data. A C2-parity byte is computed for at least some of the empty locations of the third array and a fourth array is generated. C1-parity symbols in each row are computed, generating a fifth array. A second modulation constraint is enforced on each C1-parity symbol in each row of the fifth array, generating a sixth array. The rows of the sixth array are assembled with header and sync fields for recording onto a recording media. | 09-25-2008 |
20080235562 | REVERSE CONCATENATION FOR PRODUCT CODES - Method and computer program product are provided to encode data for recording onto media whereby modulation and linear constraints from a concatenated code or product code are imposed. A first array of unencoded user data is generated. Each row is modulation encoded to enforce a first modulation constraint; the array is transformed into a second array which is transformed into a third array having predetermined empty locations in each column interleaved with the modulated data. A C2-parity byte is computed for at least some of the empty locations of the third array and a fourth array is generated. C1-parity symbols in each row are computed, generating a fifth array. A second modulation constraint is enforced on each C1-parity symbol in each row of the fifth array, generating a sixth array. The rows of the sixth array are assembled with header and sync fields for recording onto a recording media. | 09-25-2008 |
20080259484 | READ CHANNEL APPARATUS FOR ASYNCHRONOUS SAMPLING AND SYNCHRONOUS EQUALIZATION - A read channel and method using that read channel are disclosed. The read channel comprises an analog to digital converter which asynchronously samples at a fixed rate an analog signal formed by reading a data track, where that data track was written to a data storage medium at a symbol rate and an interpolator interconnected with the analog to digital converter. The read channel further comprises a fractionally-spaced equalizer, where the interpolator provides an interpolated signal to the fractionally-spaced equalizer at an interpolation rate, where that interpolation rate is greater than the symbol rate. The fractionally-spaced equalizer forms a synchronous equalized signal. The read channel further comprises a gain control module interconnected with the fractionally-spaced equalizer, and a sequence detector interconnected with the gain control module. | 10-23-2008 |
20090103202 | METHOD FOR AN EQUALIZER COMPUTATION IN A MEDIA SYSTEM USING A DATA SET SEPARATOR SEQUENCE - Provided is a method for receiving a DSS sequence and a DSS readback sequence, which is a function of a channel processing of the DSS sequence by a read channel. A coefficient cyclic equalizer vector is generated as a function of the DSS sequence and the DSS readback sequence. An error signal is generated as a function of a comparison of the DSS sequence and an equalization of the DSS readback sequence based on the coefficient cyclic equalizer vector. An unacceptable error signal indicates a need to adjust the coefficient cyclic equalizer vector to yield an acceptable comparison of the DSS sequence and an equalization of the DSS readback sequence based on the coefficient cyclic equalizer vector. | 04-23-2009 |
20090195909 | GAIN CONTROL FOR DATA-DEPENDENT DETECTION IN MAGNETIC STORAGE READ CHANNELS - Method, apparatus and computer program product adjust gain in a read channel of a magnetic media data storage device. A digital signal sample having a data-dependent noise component is received. A gain value, stored in a location in a gain table, is selected in a data-dependent manner. The gain of the signal sample is adjusted in response to the selected gain value. A bit pattern is detected from the gain-adjusted signal sample and a data output signal is output based upon the detected bit pattern. | 08-06-2009 |
20100189169 | 16-STATE ADAPTIVE NOISE PREDICTIVE MAXIMUM-LIKELIHOOD DETECTION SYSTEM - A 16-State adaptive NPML detector is provided for a tape drive which addresses weaknesses of a conventional fixed, 8-state EPR4 detector. Rather than having a fixed target channel, the detector is programmable to allow a range of target channels and can support “classical” partial response channels such as PR4 or EPR4 by programming predictor or whitening filter coefficients. In one embodiment, two filter coefficients may be set via XREG inputs or dynamically determined through the use of an LMS algorithm allowing the detector to adapt the predictor coefficients as data is being read. Another embodiment provides a detector for an EPR4 target in which the whitening filter has one coefficient. Components of the detection system include the detector itself, an LMS engine, a coefficient engine and a noise predictive or whitening filter. Coefficients from the LMS engine may be loaded or stored dynamically based upon conditions in the tape drive. | 07-29-2010 |
20100226037 | COMBINING INFORMATION FROM PARALLEL SERVO CHANNELS - A weighted combining scheme exploits information from two servo channels operating in parallel. A timing-based servo module servo module comprises two servo channels coupled respectively to receive two digital servo signals read from a data tape. Both channels have outputs for an unweighted metric and for a measure of the channel reliability. A weight computation module provides first and second weight signals using the measures of channel reliability from the servo channels. A first multiplying node receives a first unweighted metric and a first weight signal and is operable to output a first weighted metric. A second multiplying node receives a second unweighted metric and a second weight signal and outputs a second weighted metric. A summing node receives the first and second weighted metrics and outputs a combined weighted metric to an LPOS word decoder. | 09-09-2010 |
20100226039 | COMBINING INFORMATION FROM PARALLEL SERVO CHANNELS - A weighted combining scheme exploits information from two servo channels operating in parallel. A timing-based servo module comprises two synchronous servo channels coupled respectively to receive two digital servo signals read from a data tape. Both channels have outputs for an unweighted parameter estimate and for a measure of the channel reliability. A weight computation module provides first and second weight signals using the measures of channel reliability from the servo channels. An offset computation module provides first and second offset terms which are summed with the unweighted parameter estimates. Multiplying nodes receive the unweighted parameter estimates and the weight signals and outputs offset weighted parameter estimates. A summing node receives the offset weighted parameter estimates and outputs a combined offset weighted parameter estimate to a servomechanism. | 09-09-2010 |
20100302666 | DETECTING A PERIODIC SEQUENCE OF SERVO SIGNALS - A system and method are disclosed for detecting a periodic sequence. A value detector module detects a plurality of values of a periodic sequence. In one embodiment, a transformation module transforms the plurality of values into transformed values. A confinement module confines the values to a limited set of confined values. A correlation module correlates the confined values with a plurality of instances of the periodic sequence. In addition, a selection module selects an instance of the periodic sequence with the highest correlation to the confined values as an observed periodic sequence. | 12-02-2010 |
20100318867 | APPARATUS AND METHOD TO READ INFORMATION FROM AN INFORMATION STORAGE MEDIUM - A method and apparatus to read information from an information storage medium using a read channel, where that read channel includes a data cache. The invention generates an analog waveform comprising the information, and provides that analog waveform to a read channel, and generates a digital signal from that analog waveform using one or more first operating parameters. The method error corrects that digital signal at an actual error correction rate, and determines if the actual error correction rate is greater than an error correction rate threshold. If the actual error correction rate exceeds the error correction rate threshold, then the method captures the digital signal, stores that captured data in a data cache, reads that digital signal from the cache, generates one or more second operating parameters, and provides those one or more second operating parameters to the read channel. Thereafter, the method uses those one or more second operating parameters to read the information from the information storage medium. | 12-16-2010 |
20100318868 | APPARATUS AND METHOD TO READ INFORMATION FROM AN INFORMATION STORAGE MEDIUM - A method and apparatus to read information from an information storage medium using a read channel, where that read channel includes a data cache. The invention generates an analog waveform comprising the information, and provides that analog waveform to a read channel, and generates a digital signal from that analog waveform using one or more first operating parameters. The method error corrects that digital signal at an actual error correction rate, and determines if the actual error correction rate is greater than an error correction rate threshold. If the actual error correction rate exceeds the error correction rate threshold, then the method captures the digital signal, stores that captured data in a data cache, reads that digital signal from the cache, generates one or more second operating parameters, and provides those one or more second operating parameters to the read channel. Thereafter, the method uses those one or more second operating parameters to read the information from the information storage medium. | 12-16-2010 |
20100328803 | COMBINING INFORMATION FROM PARALLEL SERVO CHANNELS - A weighted combining scheme exploits information from two servo channels operating in parallel. A timing-based servo module comprises two synchronous servo channels coupled respectively to receive two digital servo signals read from a data tape. Both channels have outputs for an unweighted parameter estimate and for a measure of the channel reliability. A weight computation module provides first and second weight signals using the measures of channel reliability from the servo channels. An offset computation module provides first and second offset terms which are summed with the unweighted parameter estimates. Multiplying nodes receive the unweighted parameter estimates and the weight signals and outputs offset weighted parameter estimates. A summing node receives the offset weighted parameter estimates and outputs a combined offset weighted parameter estimate to a servomechanism. | 12-30-2010 |
20110007418 | COMBINING INFORMATION FROM PARALLEL SERVO CHANNELS - A weighted combining scheme exploits information from two servo channels operating in parallel. A timing-based servo module comprises two synchronous servo channels coupled respectively to receive two digital servo signals read from a data tape. Both channels have outputs for an unweighted parameter estimate and for a measure of the channel reliability. A weight computation module provides first and second weight signals using the measures of channel reliability from the servo channels. An offset computation module provides first and second offset terms which are summed with the unweighted parameter estimates. Multiplying nodes receive the unweighted parameter estimates and the weight signals and outputs offset weighted parameter estimates. A summing node receives the offset weighted parameter estimates and outputs a combined offset weighted parameter estimate to a servomechanism. | 01-13-2011 |
20110102927 | MULTILEVEL PULSE POSITION MODULATION FOR EFFICIENT ENCODING OF INFORMATION INTO SERVO PATTERNS - A storage medium on which servo patterns are encoded to provide lateral and longitudinal position (LPOS) information is provided. Each of the servo patterns includes a servo frame, including first through fourth bursts, which are each independently modulated with multi-level pulse position modulation (PPM) to encode at least one independent bit per burst. | 05-05-2011 |
20110176237 | MAGNETIC TAPE SERVO FORMAT ALLOWING FOR INCREASED LINEAR TAPE DENSITY AND SYSTEMS THEREOF - According to one embodiment, a magnetic recording tape includes a plurality of servo tracks, each servo track comprising a series of magnetically defined bars having an average height of between about 80 microns and about 120 microns, wherein an average stripe angle of the bars is between about 10° and about 25°. A stripe angle is measured between a longitudinal axis of each respective bar and a line oriented perpendicular to a direction of tape travel and parallel to a plane of the tape, wherein an average stripe width of the bars is between about 1.0 micron and about 2.2 microns and an average servo frame length of groups of the bars comprising a servo frame is between about 120 microns and about 180 microns. In more embodiments, a servo format and a system including a servo format are disclosed, along with other embodiments of magnetic tapes. | 07-21-2011 |
20110200090 | METHOD FOR AN EQUALIZER COMPUTATION IN A MEDIA SYSTEM USING A DATA SET SEPARATOR SEQUENCE - An equalizer coefficients generator receives a DSS sequence and a DSS readback sequence, which is a function of a channel processing of the DSS sequence by a read channel. The generator generates a coefficient cyclic equalizer vector as a function of the DSS sequence and the DSS readback sequence. The generator further generates an error signal as a function of a comparison of the DSS sequence and an equalization of the DSS readback sequence based on the coefficient cyclic equalizer vector. An unacceptable error signal indicates a need to adjust the coefficient cyclic equalizer vector to yield an acceptable comparison of the DSS sequence and an equalization of the DSS readback sequence based on the coefficient cyclic equalizer vector. | 08-18-2011 |
20110205657 | SYNCHRONIZATION OF SYMMETRIC TIMING BASED SERVO BURSTS - Timing based servo bursts of servo frames, in which the frames are arranged to be symmetric with the same number of servo stripes in each burst of a frame, are synchronized by shifting selected bits. For example, servo frames are arranged with four servo bursts with an equal number of servo stripes in each burst, the servo frames comprising two symmetric sub-frames, each sub-frame comprising two bursts of servo stripes that are parallel to each other within a burst, and the bursts are non-parallel with respect to each other; each servo burst is arranged to comprise at least one reference servo stripe; and each servo burst is arranged to comprise at least one shifted servo stripe, wherein the shift is in the same longitudinal direction with respect to at least one reference servo stripe for each burst of a frame and the opposite longitudinal direction for bursts of sequentially adjacent frames. | 08-25-2011 |
20110242692 | DATA-DEPENDENT NOISE-PREDICTIVE MAXIMUM LIKELIHOOD DETECTION (DD-NPML) FOR MAGNETIC RECORDING - In one embodiment, a method includes applying one or more whitening filters to an input stream of digitized samples from a magnetic data channel to produce a filtered sequence, performing one or more branch metric calculations to the filtered sequence to produce a branch metric, and applying a multi-state data-dependent noise-predictive maximum likelihood (DD-NPML) detector to the branch metric to produce an output stream. In another embodiment, a multi-channel data storage system includes a head for reading data from a storage medium, logic for applying one or more whitening filters to an input stream of digitized samples from a magnetic data channel to produce a filtered sequence, logic for performing one or more branch metric calculations to the filtered sequence to produce a branch metric, and logic for applying a multi-state DD-NPML detector to the branch metric to produce an output stream. Other systems and methods are described as well. | 10-06-2011 |
20110246864 | DATA DEPENDENT NPML DETECTION AND SYSTEMS THEREOF - According to one embodiment, a data detection system includes a coefficient-and-variance engine for selecting which infinite impulse response (IIR) filter and prediction error variance to process and store at any time, and a maximum-likelihood sequence detector. The coefficient-and-variance engine comprises a filter bank storing a plurality of IIR filters that represent a plurality of data-dependent noise whitening or noise prediction filters; a least-mean square (LMS) engine for adapting each IIR filter to actual noise conditions: a variance hank storing a plurality of prediction error variance values; and a data-dependent prediction error variance computation unit which updates the plurality of prediction error variance values. The maximum-likelihood sequence detector includes a metric computation unit that employs the plurality of IIR filters in the filter bank and the plurality of prediction error variances in the variance bank to adaptively compute detector branch metrics. Other systems and methods are also described in other embodiments. | 10-06-2011 |
20120144228 | Apparatus and Method to Read Information from an Information Storage Medium - A method to read information from an information storage medium using a read channel, where that read channel includes a data cache, where the method generates an analog waveform comprising the information, provides that analog waveform to a read channel generates a digital signal from that analog waveform using one or more first operating parameters, corrects that digital signal at an actual error correction rate, determines if the actual error correction rate is greater than an error correction rate threshold. If the actual error correction rate exceeds the error correction rate threshold, then the method captures the digital signal, stores that captured data in a data cache, reads that digital signal from the cache, generates one or more second operating parameters, provides those one or more second operating parameters to the read channel. | 06-07-2012 |
20130088794 | ROBUST METRIC COMPUTATION OF LONGITUDINAL POSITION (LPOS) DATA SYMBOL DETECTION - In one embodiment, a tape drive system includes a magnetic head having a servo sensor for sensing a defined servo track of a magnetic tape and configured to read servo pulses from servo bursts of the servo track while the magnetic tape is moving past the magnetic head with the servo bursts representing an encoded data symbol, an analog-to-digital converter configured to provide a sequence of samples of the readback servo signal, a digital correlator configured to compute a correlation signal between the sequence and a reference waveform, a timing reference module configured to provide a reference timing model having interpolation instants to the digital correlator, a correlation interpolator configured to interpolate the correlation signal at the interpolation instants and compute a longitudinal position (LPOS) detection metric, and an LPOS detector configured to decode the encoded data symbol of the servo bursts using the computed LPOS detection metric. | 04-11-2013 |
20130128374 | FIXING TAP COEFFICIENTS IN A PROGRAMMABLE FINITE-IMPULSE-RESPONSE EQUALIZER - A method for selecting which tap coefficients of a programmable finite-impulse-response (FIR) equalizer to fix is disclosed. In one embodiment, such a method includes performing an initial calibration to determine an initial value for each tap coefficient of a FIR equalizer. These initial values may be used to produce a first waveform. The method then performs an operation on the first waveform to produce a second waveform comprising multiple lobes. The second waveform is then analyzed to determine one or more lobes of the second waveform that have the largest area. The method then fixes coefficients of one or more taps that are closest to the lobe or lobes having the largest area. A corresponding apparatus and computer program product are also disclosed. | 05-23-2013 |
20130222940 | MAGNETIC TAPE SERVO FORMAT ALLOWING FOR INCREASED LINEAR TAPE DENSITY AND SYSTEMS THEREOF - In one general embodiment, a magnetic recording tape includes a plurality of servo tracks, each servo track comprising a series of magnetically defined bars, wherein an average stripe width of the bars is between about 1.0 micron and about 2.2 microns, where an average servo frame length of groups of the bars comprising a servo frame is between about 120 microns and about 180 microns. In another general embodiment, a system includes a head having at least one servo reader and an array of data transducers of a type selected from a group consisting of readers and writers; and a controller operative to selectively enable every other transducer of a particular type in the array in a first mode of operation, and operative to selectively enable every transducer of the particular type in the array in a second mode of operation. | 08-29-2013 |
20130279040 | COMBINED SOFT DETECTION/SOFT DECODING IN TAPE DRIVE STORAGE CHANNELS - In one embodiment, a tape drive system includes a soft detector for executing a first forward loop of a detection algorithm on a first block of signal samples during a first time interval; and logic for executing forward and reverse loops during several time intervals; and logic adapted for outputting a first decoded block of signal samples based on the executing the decoding algorithm on the first block during a sixth time interval, wherein a sum of second, third, fourth, fifth, and sixth time intervals are about equal in duration to the first time interval. | 10-24-2013 |
20130283127 | COMBINED SOFT DETECTION/SOFT DECODING IN TAPE DRIVE STORAGE CHANNELS - 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. | 10-24-2013 |
20130326305 | DATA FORMAT USING AN EFFICIENT REVERSE CONCATENATED MODULATION CODE FOR MAGNETIC TAPE RECORDING - 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. | 12-05-2013 |
20130326306 | PARTIAL REVERSE CONCATENATION FOR DATA STORAGE DEVICES USING COMPOSITE CODES - 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 C2 encoding 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 C2-encoded data sets using a C1 encoding scheme, logic adapted for combining the C1-encoded portions with the modulation-encoded headers of the C2-encoded data sets using a multiplexer, and logic adapted for writing the one or more combined C1- and C2-encoded data sets to data tracks. | 12-05-2013 |
20130326307 | METHODS FOR PARTIAL REVERSE CONCATENATION FOR DATA STORAGE DEVICES USING COMPOSITE CODES - In one embodiment, a method includes writing data to a storage medium of a data storage system using a partial reverse concatenated modulation code by encoding data sets using a C2 encoding scheme, adding a header to each subunit of the data sets, encoding the headers of the data sets with a first modulation encoding scheme, encoding data portions of the data sets with a second modulation encoding scheme, encoding portions of the one or more C2-encoded data sets using a C1 encoding scheme, combining the C1-encoded portions with the modulation-encoded headers of the C2-encoded data sets using a multiplexer, and writing the one or more combined C1- and C2-encoded data sets to data tracks of the storage medium. Other methods 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. | 12-05-2013 |
20130326311 | MAGNETIC TAPE RECORDING IN DATA FORMAT USING AN EFFICIENT REVERSE CONCATENATED MODULATION CODE - 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. | 12-05-2013 |
20130335845 | ADAPTIVE SOFT-OUTPUT DETECTOR FOR MAGNETIC TAPE READ CHANNELS - In one embodiment, a data storage system includes a tape channel for reading data from a tape to produce a signal, an adaptive noise whitening filter adapted for receiving the signal, the noise whitening filter being adapted for minimizing variance of noise affecting the signal output from the noise whitening filter, a soft DMAX detector adapted for receiving the signal from the noise whitening filter, the soft detector adapted for calculating first soft information about each bit of the signal and sending the first soft information to a soft decoder, and the soft decoder positioned subsequent to the soft detector, the soft decoder being adapted for calculating second soft information about each bit of the signal and sending the second soft information to the soft DMAX detector, wherein one or more noise whitening coefficients used in the noise whitening filter are updated using a noise whitening filter coefficient updater. | 12-19-2013 |
20130335846 | ADAPTIVE SOFT-OUTPUT DETECTOR FOR MAGNETIC TAPE READ CHANNELS - In accordance with one embodiment, a data storage system includes a tape channel for reading precoded data from a magnetic tape medium to produce a signal, a soft detector adapted for calculating first soft information about each bit of the signal and sending the first soft information to a soft decoder, and the soft decoder positioned subsequent to the soft detector, the soft decoder being adapted for calculating second soft information about each bit of the signal and sending the second soft information to the soft detector, wherein the precoded data includes a characteristic of being passed through at least one precoder prior to being written to the magnetic tape medium, and wherein the soft detector provides automatic compensation for the precoded data. Other systems, methods, and computer program products for reading data using an adaptive soft-output detector are described according to more embodiments. | 12-19-2013 |
20130335848 | ADAPTIVE SOFT-OUTPUT DETECTOR FOR MAGNETIC TAPE READ CHANNELS - In one embodiment, a data storage system includes a tape channel for reading data from a magnetic tape medium to produce a signal, a noise whitening filter positioned subsequent to the tape channel adapted for receiving the signal, wherein the noise whitening filter is adapted for minimizing variance of its output signal, a soft detector adapted for receiving output from the noise whitening filter, the soft detector adapted for calculating first soft information about each bit of the signal and sending the first soft information to a soft decoder, and the soft decoder positioned subsequent to the soft detector, the soft decoder being adapted for calculating second soft information about each bit of the signal and sending the second soft information to the soft detector. Other systems, methods, and computer program products are described according to more embodiments. | 12-19-2013 |
20130335849 | ADAPTIVE SOFT-OUTPUT DETECTOR FOR MAGNETIC TAPE READ CHANNELS - In one embodiment, a system includes a tape channel for reading data from a magnetic tape medium to produce a signal, a bank of noise whitening filters positioned subsequent to the tape channel adapted for receiving the signal, the bank of noise whitening filters being adapted for minimizing variance of noise affecting the signal at an output of the bank of noise whitening filters, wherein each noise whitening filter in the bank of noise whitening filters is dependent on a different possible data pattern, a soft DMAX detector adapted for calculating first soft information, dependent on the different possible data patterns, about each bit of the signal from the bank of noise whitening filters, and sending the first soft information to a soft decoder adapted for calculating second soft information about each bit of the signal and sending the second soft information to the soft DMAX detector. | 12-19-2013 |
20140036382 | ROBUST METRIC COMPUTATION OF LONGITUDINAL POSITION (LPOS) DATA SYMBOL DETECTION - An apparatus according to one embodiment includes a digital correlator configured to compute a correlation signal between a sequence of samples of a readback servo signal and a reference waveform. A timing reference module is configured to provide a reference timing model comprising one or more interpolation instants to the digital correlator, wherein the correlation signal determined at each interpolation instant yields a detection metric for one data symbol. A correlation interpolator is configured to interpolate the correlation signal at the interpolation instants and compute a longitudinal position (LPOS) detection metric according to the interpolated correlation signal samples. | 02-06-2014 |
20140108881 | BLOCK-INTERLEAVED AND ERROR CORRECTION CODE (ECC)-ENCODED SUB DATA SET (SDS) FORMAT - In one embodiment, a system for encoding data includes logic adapted for receiving data having one or more sub data sets, a C1 encoder module adapted for generating a plurality of C1 codewords during C1 ECC encoding of the one or more sub data sets, logic adapted for interleaving the plurality of C1 codewords into C1 codeword interleaves (CWIs), each CWI having a predetermined number of C1 codewords interleaved therein, a C2 encoder module adapted for generating a plurality of C2 codewords during C2 ECC encoding of the one or more sub data sets, wherein each C2 codeword has at most one symbol from each C1 codeword in each CWI, and wherein each C2 codeword has one symbol from at least two different C1 codewords in each CWI, and logic adapted for writing the one or more encoded sub data sets to a storage medium. | 04-17-2014 |
20140189461 | UNEQUAL ERROR PROTECTION SCHEME FOR HEADERIZED SUB DATA SETS - In one embodiment, a method includes receiving a headerized SDS protected by unequal error protection; decoding a header from the headerized SDS and removing an impact of the header from C1 row parity to obtain a SDS; for a number of iterations: performing C2 column decoding, for no more than a number of interleaves in each row of the SDS: overwriting a number of columns with successfully decoded C2 codewords, erasing a number of C2 codewords, and maintaining remaining columns as uncorrected, performing C1 row decoding; for no more than a number of interleaves in each row of the SDS: overwriting a number of rows with successfully decoded C1 codewords, erasing a number of C1 codewords, and maintaining remaining rows as uncorrected; and outputting the SDS when all rows include only C1 codewords and all columns include only C2 codewords; otherwise, outputting indication that the SDS cannot be decoded properly. | 07-03-2014 |
20140347762 | COMBINED SOFT DETECTION/SOFT DECODING IN TAPE DRIVE STORAGE CHANNELS - 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. | 11-27-2014 |
20140355147 | CYCLE-SLIP RESILIENT 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. | 12-04-2014 |
20140355149 | ITERATIVE DATA STORAGE READ CHANNEL ARCHITECTURE HAVING DROPOUT MITIGATION - According to one embodiment, a magnetic medium's readback signal samples are processed iteratively to provide dropout mitigation for a 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. | 12-04-2014 |
20140355151 | TAPE HEADER PROTECTION SCHEME FOR USE IN A TAPE STORAGE SUBSYSTEM - In one embodiment, a system for integrating data and header protection in tape recording includes a processor and logic adapted to: provide a data array organized in rows and columns, each row of the data array including four interleaved C1 codewords (CWI-4), add a header to each row of the data array, each header including a CWI-4 Designation (CWID) which indicates a location of the CWI-4 within the data array, calculate ECC parity for at least one C1 codeword in each of the headerized rows, and modify the headerized rows to include the ECC parity, wherein each modified row includes four interleaved codewords, at least one codeword being a C1′ codeword which includes ECC parity for a data portion of a C1 codeword and a portion of a header, wherein none of the CWIDs are split across multiple C1′ codewords in a single modified row. | 12-04-2014 |
20140359396 | ITERATIVE DATA STORAGE READ CHANNEL ARCHITECTURE - In one embodiment, a method for iterative read channel operation includes executing digital front-end (DFE) functions on signal samples employing decisions provided by a detector executing a detection algorithm, executing an error correcting code (ECC) decoding algorithm on the signal samples using a decoder employing the decisions provided by the detector to generate decisions provided by the decoder, storing the signal samples and the decisions provided by the detector and the decoder, and in an iterative process: executing the DFE functions on the signal samples employing the decisions provided by the decoder, executing the detection algorithm on the signal samples using the detector employing the decisions provided by the decoder to regenerate the decisions provided by the detector, executing the decoding algorithm using the decisions provided by the detector to regenerate the decisions provided by the decoder, and outputting decoding information when the decoding algorithm produces a valid codeword. | 12-04-2014 |
20140380118 | UNEQUAL ERROR PROTECTION SCHEME FOR HEADERIZED SUB DATA SETS - A method for decoding a headerized sub data set (SDS) according to one embodiment includes decoding a header from a headerized SDS to obtain a SDS. C1 and C2 decoding are performed on the SDS in a number of iterations based on a number of interleaves in each row of the SDS. A number of columns of the SDS are overwritten with successfully decoded C2 codewords. A number of rows of the SDS are overwritten with successfully decoded C1 codewords. A number of C1 and/or C2 codewords of the SDS are erased. Remaining rows and/or columns of the SDS are maintained as uncorrected. The SDS is output when all rows of the SDS include only C1 codewords and all columns of the SDS include only C2 codewords. | 12-25-2014 |
20150015982 | OPTIMUM TAPE LAYOUT SELECTION FOR IMPROVED ERROR CORRECTION CAPABILITY - According to one embodiment, a system for selecting an optimum tape layout to store data on a tape medium may include a processor and logic integrated with and/or executable by the processor, the logic being configured to: select a family of data set layouts based on parameters associated with at least a tape drive and the tape medium, compute a set of all minimum distances for the selected family of data set layouts, calculate a first performance metric associated with each possible set of parameters, select a best first performance metric from all calculated first performance metrics and store a set of parameters associated with the best first performance metric, and select a data set layout algorithm which utilizes the set of parameters associated with the best first performance metric, wherein the data set layout algorithm and a rewrite layout algorithm combine to form an optimum tape layout. | 01-15-2015 |
20150046767 | COMBINATION ERROR AND ERASURE DECODING FOR PRODUCT CODES - In one embodiment, a system for combination error and erasure decoding for product codes includes a processor and logic integrated with and/or executable by the processor, the logic being configured to receive captured data, generate erasure flags for the captured data and provide the erasure flags to a C2 decoder, set a stop parameter to be equal to a length of C1 codewords in a codeword interleave used to encode the captured data, and selectively perform, in an iterative process, error or erasure C1 decoding followed by error or erasure C2 decoding until decoding is successful or unsuccessful. In more embodiments, a method and/or a computer program product may be used for combination error and erasure decoding for product codes. | 02-12-2015 |
20150058696 | TAPE HEADER FORMAT HAVING EFFICIENT AND ROBUST CODEWORD INTERLEAVE DESIGNATION (CWID) PROTECTION - In one embodiment, a system for providing header protection in magnetic tape recording is adapted to write a codeword interleave (CWI) set on a magnetic tape including a plurality of CWIs equal to a number of tracks, wherein a data set includes a plurality of CWI sets, provide a CWI set header for the CWI set, the CWI set header including a CWI header for each CWI in the CWI set, each CWI header including at least a CWI Designation (CWID) which indicates a location of the CWI within the data set, calculate or obtain CWID parity for all CWIDs in the CWI set header, the CWID parity including error correction coding (ECC) parity, and store the CWID parity to one or more fields which are repeated for each CWI header in the CWI set header without using reserved bits in the CWI set header to store the CWID parity. | 02-26-2015 |
20150085393 | TAPE HEADER PROTECTION SCHEME FOR USE IN A TAPE STORAGE SUBSYSTEM - In one embodiment, a system for integrating data and header protection includes a processor and logic integrated with and/or executable by the processor, the logic being configured to receive a data array organized in rows and columns, each row of the data array comprising two or more interleaved C1 codewords (CWI), and modify one or more rows of the data array to include a header and error correction code (ECC) parity to form one or more modified rows, wherein each modified row includes two or more interleaved codewords, at least one codeword being a C1′ codeword which includes ECC parity, wherein each header comprises a CWI Designation (CWID) which indicates a location of the CWI within the data array, and wherein none of the CWIDs are split across multiple C1′ codewords in a single modified row. Other systems, methods, and computer program products are presented in additional embodiments. | 03-26-2015 |