Abstract: A method of setting an upper limit value of the number of write times, which is applied to a magnetic disk device including a disk and a head configured to write data to the disk and read the data from the disk, includes measuring a plurality of bit error rates in a recording area of the disk upon repeatedly writing to an area of the disk adjacent to the recording area a number of write times, deriving a function that approximates a bit error rate in relation to a number of write times, using the measured bit rates corresponding to at least a first number of write times, a second number of write times, and a third number of write times, and applying the function to determine a number of write times that correspond to a first threshold bit error rate that makes the data on the disk unreadable, and setting the determined number of write times as the upper limit value of the number of write times.

Abstract: According to one embodiment, a recording and reproducing apparatus includes a first masking unit configured to apply first bit masking to error correction code (ECC) encoded data using a bit sequence for masking, to generate a masked bit sequence to be recorded on a medium, and a de-masking unit configured to apply de-masking, using the bit sequence for masking, to a sequence of decision values based on a signal read from the medium to generate a sequence of de-masked decision values to be ECC decoded. The bit sequence for masking comprises an iteration of a fixed bit sequence of N (>1) bits. The bit de-masking is an inverse process corresponding to the first bit masking.

Abstract: According to one embodiment, there is provided a controller including an interference cancelling module, a boosting module, and a decoding module. The interference cancelling module generates a first correction signal by cancelling an interference component from an adjacent track in a signal read from a target track of a disk medium. The boosting module generates a second correction signal by boosting a low frequency component of a signal corresponding to the first correction signal. The decoding module decodes a signal based on the second correction signal.

Abstract: A decoder and recording/reproducing device for preventing an increase in power consumption, has a multi-step iterative decoder. The decoder includes an iterative decoder in which a decoder constituted by a channel decoder and an outer code decoder is installed in multiple steps; an iterative decoding control circuit which estimates an error symbol count after decoding using likelihood information obtained from the outer decoder, stops the interactive decoding, if the estimated error symbol count exceeds an error symbols count, and corrects the residual errors that can be corrected by ECC using the ECC decoder. Therefore if a multi-step iterative decoder is used, the number of times of iterative decoding can be decreased and low power consumption can be implemented.

Abstract: An ECC determining unit determines whether an error detected by using an ECC has been corrected. When the detected error has not been corrected, an equalizer output sequence transfer unit transfers an equalizer output sequence yk stored in an equalizer output sequence storage unit to a transfer data storage unit in a hard disk controller, so that a high-performance decoding unit (software) performs repetitive decoding, using the transferred equalizer output sequence yk.

Abstract: A disk storage device has a plurality of disk faces and a plurality of heads, in which a different S/N is improved for each head. The disk face is formatted in a sector format with which the read/write characteristics become the optimum using the fact that the read/write characteristics differ depending on the sector length, so an improvement of the S/N ratio can be expected compared with a conventional recording/reproducing device using a single format, and the device yield rate and the device performance can be improved, and high recording density can be implemented.

Abstract: Upon data recording, a data recording unit inserts revise bytes as a predetermined specific code train into at least two or more portions including the head and last portions of data and records the data onto a medium. Upon data reproduction, a data reproducing unit separates a head reproduced signal by using clocks and, thereafter, executes a clock extraction and an amplitude correction by using a signal corresponding to the revise bytes as a specific code train. In principle, an RLL code for the clock extraction and gain tracking is eliminated and, in place of the RLL code, the revise bytes comprising the specific code train are inserted into the data and the data is recorded onto the medium.

Abstract: In a Maximum A posteriori Probability decoding (MAP decoding), a correlation and a deviation of noises for past and future states which depend on input signal patterns in past N bits and future Q bits are calculated by training by a noise correlation arithmetic operating unit 84 and they are stored. Upon reproduction, in a white noise arithmetic operating unit 91, white noise values for the past and future states in which colored noises are converted into white noises are obtained by using the stored correlation and deviation of the noises. In an input signal arithmetic operating unit 92, an input signal (channel information) ?c(yk|Smk) of the MAP decoding is calculated from the white noise values and the deviation for the past and future states. A likelihood in the MAP decoding is obtained from the input signal.

Abstract: A magnetic recording and/or reproducing apparatus includes an equalization section for equalizing a signal sequence which is reproduced from a magnetic recording medium and outputting an equalized waveform, and a conversion section for converting the equalized waveform into a maximum likelihood sequence by carrying out metric calculation based on average values of the equalized waveform.

Abstract: An ECC determining unit determines whether an error detected by using an ECC has been corrected. When the detected error has not been corrected, an equalizer output sequence transfer unit transfers an equalizer output sequence yk stored in an equalizer output sequence storage unit to a transfer data storage unit in a hard disk controller, so that a high-performance decoding unit (software) performs repetitive decoding, using the transferred equalizer output sequence yk.

Abstract: Upon data recording, a data recording unit inserts revise bytes as a predetermined specific code train into at least two or more portions including the head and last portions of data and records the data onto a medium. Upon data reproduction, a data reproducing unit separates a head reproduced signal by using clocks and, thereafter, executes a clock extraction and an amplitude correction by using a signal corresponding to the revise bytes as a specific code train. In principle, an RLL code for the clock extraction and gain tracking is eliminated and, in place of the RLL code, the revise bytes comprising the specific code train are inserted into the data and the data is recorded onto the medium.

Abstract: In a Maximum A posteriori Probability decoding (MAP decoding), a correlation and a deviation of noises for past and future states which depend on input signal patterns in past N bits and future Q bits are calculated by training by a noise correlation arithmetic operating unit 84 and they are stored. Upon reproduction, in a white noise arithmetic operating unit 91, white noise values for the past and future states in which colored noises are converted into white noises are obtained by using the stored correlation and deviation of the noises. In an input signal arithmetic operating unit 92, an input signal (channel information) &Lgr;c(yk|Smk) of the MAP decoding is calculated from the white noise values and the deviation for the past and future states. A likelihood in the MAP decoding is obtained from the input signal.

Abstract: A magnetic recording and/or reproducing apparatus includes an equalization section for equalizing a signal sequence which is reproduced from a magnetic recording medium and outputting an equalized waveform, and a conversion section for converting the equalized waveform into a maximum likelihood sequence by carrying out metric calculation based on average values of the equalized waveform.