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.

There is provided a signal processing apparatus and a signal processing method capable of allowing data recorded at a high density to be robustly reproduced. A frame sync (FS) is restored by performing maximum likelihood decoding of the FS according to a time-varying trellis with a state and a state transition being limited according to a time, in maximum likelihood decoding of a reproduction signal reproduced from a disk-shaped recording medium, the FS representing a head of a frame, the FS of the frame being arranged at the head of the frame, the FS being recorded at the same positions in a track direction in two adjacent tracks.

Data detection capability is improved by whitening crosstalk noise from an equalization signal and detecting binary data. Each of a plurality of detection signals is input to one of a plurality of adaptive equalizers, and outputs of the plurality of adaptive equalizers are computed to obtain an equalization signal for returning light at the time of shining of light onto bounds including a target track subject to data detection and adjacent tracks of an optical recording medium having a plurality of tracks formed thereon. Crosstalk noise from the adjacent tracks included in the equalization signal obtained by this multi-input adaptive equalization process is whitened first, followed by a binarization process. Also, an equalization error is found, and supplied as a control signal for adaptive equalization. Further, a whitening factor updating process is also performed to adaptively update a filter factor of a whitening filter.

The present invention relates to a method for controlling a bit rate and an apparatus therefor, and more specifically to an apparatus for storing a bit rate changed according to a significant level in a memory and a method for determining the bit rate, which meets the requirements for the distortion according to the memory space limitation and the significant level of the image information so as to minimize the energy consumption.

In one embodiment, a data storage system includes a head configured to produce a signal representing data stored on a storage medium, a bank of noise whitening filters configured to apply one or more noise whitening filters to the signal to produce a filtered signal, and a data-dependent noise mean calculator configured to estimate a data-dependent noise mean from the filtered signal. The system also includes a branch metric calculator configured to perform one or more branch metric calculations on the filtered signal to produce one or more branch metrics, the one or more branch metric calculations accounting for the data-dependent noise mean. Moreover, the system includes an adaptive data-dependent noise-predictive maximum likelihood (D3-NPML) detector configured to generate an output stream from the one or more branch metric calculations.