According to one embodiment, a magnetic disk device includes a disk including two first servo sectors and at least a second servo sector, a head, and a controller, wherein the first servo sector includes burst data and a first data pattern written before the circumferential direction of the burst data, the second servo sector includes the burst data, the first data pattern, and a second data pattern written after the circumferential direction of the burst data, a first frequency of the first data pattern is different from a second frequency of the second data pattern, and a first length of the first data pattern is different from a second length of the second data pattern.

A disk device includes a disk medium, a magnetic recording head, a processor configured to control the magnetic recording head to write data to and read data from a plurality of tracks of the disk medium on a sector-by-sector basis, and a check value generation circuit configured to generate, for each of the plurality of tracks, check value data based on data stored in one or more sectors of the track. The processor controls the magnetic recording head to write check value data for a first track of the plurality of tracks in a first sector on the disk medium and check value data for a second track of the plurality of tracks in a second sector on the disk medium that is adjacent to the first sector.

Systems and methods are disclosed for error recovery in a digital data channel. In an error recovery approach when the hardware fails to recover a sector, the sample for that sector can be saved along with a metric measure that indicates the quality of the sample. This process can begin from a first on-the-fly receiving and decoding of data. During each step of error recovery, a retry attempt may either use samples obtained during a new decoding attempt or may use a sample, or a combination of samples, having the best metric from an earlier attempt, or a combination of earlier attempts, to perform the recovery during a current retry recovery attempt.

The present application discloses a forward and backward smooth decoding method and device suitable for an OvXDM system, and a system. Importance weights of particles in a particle set corresponding to a symbol are calculated by using a forward process and a backward process, and screening is performed with reference to forward importance weights of particles and backward importance weights of particles, to output a final decoding sequence.

According to one embodiment, a magnetic disk device including a disk, a head which writes data to the disk and reads data from the disk, and a controller which sets a first DOL for a first sector group and a second DOL for a second sector group to different values, the first sector group including one or more first sectors and a first parity sector, the first sectors which allow an error correction process to be performed for each track based on the first parity sector, and are continuously arranged in a circumferential direction of the disk from the first parity sector, the second sector group including one or more second sectors which allow no error correction process to be performed for each track, and are continuously arranged in the circumferential direction.

According to one embodiment, a magnetic reproduction processing device includes a decoder. The decoder includes a convolutional layer including a plurality of filters, and an attention layer configured to derive a degree of contribution related to the filters. The decoder is configured to output a decoded result obtained by integrating results of processing an input signal with the filters according to the degree of contribution.

A memory system includes a memory device, a command clock (CK_t clock) that provides a first clock signal at a first frequency, and a data path clock (WCK_t clock) that provides a second clock signal at a second frequency different than the first frequency. Data path circuitry is synchronized with the WCK_t clock and provides an error detection code (EDC) hold pattern during an idle state. EDC hold pattern synchronization logic synchronizes a start of transmission of the EDC hold pattern synchronous to the CK_t clock.

Methods, apparatuses and systems for detecting defective sectors on a recording medium. A defective sector detector apparatus comprises an error-corrected ECC symbol number calculator and a defective sector determination unit. The error-corrected ECC symbol number calculator is configured to count a total number of error correcting code (ECC) symbols that are error-corrected in data read from data sectors on a track of a recording medium of the storage device. The defective sector determination unit is configured to receive the total number of ECC symbols that are error-corrected for a data sector from the error-corrected ECC symbol number calculator and determine whether the total number of ECC symbols that are error-corrected exceeds a threshold value. If it is determined that the total number of ECC symbols that are error-corrected exceeds the threshold value, the defective sector determination unit outputs information indicating the data sector to be a defective sector.

A disk device includes a disk medium, a magnetic recording head, a processor configured to control the magnetic recording head to write data to and read data from a plurality of tracks of the disk medium on a sector-by-sector basis, and a check value generation circuit configured to generate, for each of the plurality of tracks, check value data based on data stored in one or more sectors of the track. The processor controls the magnetic recording head to write check value data for a first track of the plurality of tracks in a first sector on the disk medium and check value data for a second track of the plurality of tracks in a second sector on the disk medium that is adjacent to the first sector.

The present application discloses a forward and backward smooth decoding method and device suitable for an OvXDM system, and a system. Importance weights of particles in a particle set corresponding to a symbol are calculated by using a forward process and a backward process, and screening is performed with reference to forward importance weights of particles and backward importance weights of particles, to output a final decoding sequence.