Abstract: 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.

Abstract: 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.

Abstract: A method for symbol timing recovery is disclosed. The method comprises receiving a plurality of timing-error estimates for a plurality of read channels, where each of the timing-error estimates corresponds to one of the read channels. The method further comprises calculating a common phase based on the plurality of timing-error estimates, and calculating a skew of a transducer array based on the plurality of timing-error estimates. Finally, the method comprises calculating a different total phase estimate for each read channel based on the calculated common phase and the calculated skew of the transducer array.

Abstract: According to one embodiment, a system for processing data includes a processor and logic integrated with and/or executable by the processor, the logic being configured to individually set, for each of one or more range-constrained finite impulse response (FIR) filter taps configured for use in a FIR filter, a predetermined range of values suitable for controlling an equalizer response, and pass data through the equalizer including the FIR filter to obtain equalized data, wherein each of the one or more range-constrained FIR filter taps are individually adaptive within its predetermined range of values. Other systems and methods for processing data by constraining FIR filter taps while reading data from a data storage medium are described in more embodiments.

Abstract: 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.

Abstract: In one embodiment, a system for processing data includes an equalizer having a finite impulse response (FIR) filter configured to process data read with a channel using servo coefficients to generate equalized data, and one or more low-pass filters configured to filter the equalized data to output filtered data. The one or more low-pass filters is configured to remove high frequency noise from the equalized data. A method for processing data in a read channel, in one embodiment, includes receiving data read from a magnetic tape using the read channel of a magnetic tape drive. A finite impulse response (FIR) filter is applied to the data by an equalizer using servo coefficients to output equalized data. One or more low-pass filters is applied to the equalized data to obtain filtered data, the one or more low-pass filters being configured to remove high frequency noise from the equalized data.

Abstract: In one embodiment, a method is provided to receive a set of data and in an iterative process: C1 decode all first subsets of the set of data two or more times in each half iteration using two or more C1-decoding methods when a first subset is not decoded successfully using a first C1-decoding method, determine whether to stop decoding the set of data after the C1 decoding and output results of the C1 decoding, increment a half iteration counter to indicate completion of a half iteration, C2 decode all second subsets of the set of data, determine whether to stop decoding the set of data after the C2 decoding and output results of the C2 decoding, increment the half iteration counter to indicate completion of another half iteration, and output the set of decoded data when all subsets of the set of data are decoded successfully.

Abstract: In one embodiment, a system for processing data includes a processor and logic integrated with and/or executable by the processor. The logic is configured to detect and track positive peak amplitudes and negative peak amplitudes of a readback waveform during data reading using a tracking threshold module, and to detect and track positive peak amplitudes and negative peak amplitudes of the readback waveform during the data reading at an input to an equalizer using a second tracking threshold module in response to reading a data set separator (DSS). Moreover, the logic is configured to perform asymmetry compensation on the data using an asymmetry compensator in an asymmetry compensation loop based on input from the tracking threshold module when not reading a DSS and based on input from the second tracking threshold module when reading a DSS, an output of the asymmetry compensator being provided to the equalizer.

Abstract: 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.

Abstract: In one embodiment, a method for combination error and erasure decoding for product codes includes receiving, using a hardware processor, captured data. The method also includes generating, using the hardware processor, erasure flags for the captured data and providing the erasure flags to a C2 decoder. Moreover, the method includes setting a stop parameter to be equal to a length of C1 codewords in a codeword interleave used to encode the captured data. In addition, the method includes selectively performing, in an iterative process, error or erasure C1 decoding followed by error or erasure C2 decoding until decoding is successful or unsuccessful. Other methods and computer program products are described in more embodiments.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: According to one embodiment, a system for processing data includes a processor and logic integrated with and/or executable by the processor, the logic being configured to read data from a magnetic data storage medium using a read channel, detect and track positive peak amplitudes and negative peak amplitudes of a readback waveform during the data reading using a tracking threshold module, and perform asymmetry compensation on the data using an asymmetry compensator based on input from the tracking threshold module in an asymmetry compensation loop, wherein the asymmetry compensator does not rely on an input from path metrics in order to perform the asymmetry compensation. Other systems, such as magnetic tape drives, and methods for processing data, and specifically for asynchronously providing asymmetry compensation for data read from a magnetic tape, are described in more embodiments.

Abstract: In one embodiment, a computer program product for providing header protection in magnetic tape recording includes a computer readable storage medium having program instructions embodied therewith, the program instructions readable by a processor to cause the processor to: calculate or obtain, by the processor, codeword interleave designation (CWID) parity for all CWIDs in a codeword interleave (CWI) set header, the CWID parity including error correction coding (ECC) parity, and store, by the processor, the CWID parity to a magnetic tape in 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. Other systems and methods for providing header protection in magnetic tape recording are described in more embodiments.

Abstract: 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.