Fujitsu Corporation

Marvell Asia Pte., Ltd.

Takao Sugawara

Yoshifumi Mizoshita

Keiji Aruga

Masaru Sawada

Toshihiko Morita

Motomu Takatsu

Tomoyoshi Yamada

Shinji Koganezawa

Yasumasa Kuroba

Takenori Ohshima

Hiroyuki Mase

Masaru Matsumoto

Toru Kouhei

Akihiro Yamazaki

Kazuhito Ichihara

Masao Tsunekewa

Yuichi Sato

Hiroshi Mutoh

Kiichirou Kasai

Toshio Ito

Mitsuhiko Ohta

Umeo Oshio

Masao Tsunekawa

Takahiro Inoue

Shinichiro Kuno

Shin Tomimoto

Takashi Aikawa

Taketoshi Aratani

Tetsuya Mukunoki

Kazuteru Hashizume

Kiyoharu Yagyu

Methods and systems are disclosed for controlling fly-height of a read/write (RW) head. In an embodiment, a RW channel detects a servo gate signal and toggles a mode signal within a preamplifier from a RW data mode signal to a fly-height control (FHC) mode signal. In response to the FHC mode signal, the RW channel transmits FHC data over a differential interface to the preamplifier.

Differential interface transmission of fly-height control data

A record reproduction apparatus includes an encoding unit that encodes sector data to be written into a recording medium, by dividing the data into a predetermined number of blocks, and an iterative decoding unit that iteratively decodes the sector data read from the recording medium, by dividing the sector data into the predetermined number of blocks.

Record reproduction method, apparatus, and circuit for using error correcting code

A timing recovery unit detects a phase offset and a frequency offset from a head area of reproduction data and initially corrects them. The timing recovery unit stores data in which a head reproduction signal has been made to be discrete by a fixed clock into a buffer. A phase offset detector detects the phase offset from the data head area in parallel with the operation for writing the data into the buffer. At the same time, a frequency offset detector detects the frequency offset from the data head area in parallel with the operation for writing the data into the buffer. A correction value of the detected phase offset and a correction value of the detected frequency offset are initially set into a digital PLL. While the data is read out from the buffer, a frequency lead-in and a phase lead-in are executed in the head area.

Information recording and reproducing apparatus and method, and signal decoding circuit for performing timing recovery

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 ystored 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 y.

Method of and apparatus for reading recording medium, harddisk controller

A timing recovery method samples, equalizes and detects a signal reproduced from a recording medium and to output a detection signal, controls sampling positions based on a phase error between the equalized signal and the detection signal, and obtains likelihood information which is related to a bit having a probability of error which exceeds a predetermined value, based on the equalized signal. The control of the sampling positions is suppressed during a time which is based on the likelihood information.

Timing recovery method and storage apparatus for suppressing control of sampling positions

In a training operation for optimizing a multiplication coefficient for each tap of an FIR equalizer equalizing a read signal read from a recording medium, as a restricted coefficient updating vector applied for updating the multiplication coefficient for each tap of an FIR filter, a vector is utilized which is obtained by projecting, onto a plane perpendicular to a predetermined restricting conditioning vector, a coefficient updating vector determined based on an equalizer error between the output of the FIR equalizer and a reproduction output determined therefrom and a delayed input value for each tap of the FIR equalizer. As the restricting conditioning vector, a vector is utilized which is a difference between a subsequent coefficient vector obtained in the same condition immediately subsequent to and an antecedent coefficient vector obtained in the same condition immediately antecedent to a reference coefficient comprising the multiplication coefficient for the equalizer obtained upon calculating the equalizer error.

Training method for recording medium reproduction equalizer and recording medium reproduction apparatus

A recording and reproducing apparatus having an ECC-less error correction function, includes an erasure detector generating an erasure flag indicating erasure of a read signal; and an iterative decoder having two soft-in/soft-out (SISO) decoders, i.e., an inner decoder and an outer decoder, and correcting the erasure by inputting the erasure flag einto the inner decoder and performing erasure compensation in the inner decoder. As the erasure compensation in the inner decoder, channel information is masked while the erasure flag is on. The erasure of data due to a media defect is detected inside the iterative decoder, and the second erasure flag is inputted into the inner decoder to perform erasure compensation in the inner decoder.

Recording and reproducing apparatus, signal decoding circuit, error correction method and iterative decoder

A recording and reproducing apparatus includes an RLL encoder that encodes an information bit string to a code bit string and a RLL decoder that decodes the code bit string to the information bit string. The RLL encoder encodes the information bit string to the code bit string of a run-length-limited code at a high encoding rate satisfying a plurality of conditions of constraint regarding a string of successive zeros. The RLL decoder decodes the code bit string encoded by the RLL encoder to the information bit string.

Recording and reproducing apparatus

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.

Information recording and reproducing apparatus, signal decoding circuit, and information recording medium and method

A magnetic head testing apparatus includes reference information storing unit for holding a predetermined reference sampling period and a number of reference samplings, sampling unit for sampling reproduced data read a plurality of times from a magnetic medium in the reference sampling period, sampling number acquiring unit for acquiring a sampling number of measured data from a reproduced data base on a sampling result, sampling number ratio calculating unit for calculating a ratio of the sampling number of the measured data and the number of reference samplings, sampling data re-acquiring unit for changing the sampling period of the measured data depending on the calculated ratio and re-acquiring the sampling data and a measured data overlap-displaying unit for overlap-display of the sampling data re-acquired from the measured data a plurality of times.

Magnetic head testing apparatus

An information recording/reading apparatus employs a preamble to reproduce a clock used when recording information in a recording medium and reads the information out of the recording medium at a timing synchronized with a read signal. The preamble is split and recorded by replacing a middle portion of the preamble with data and a sync byte. While a first buffer is employed to delay signal data read out of the recording medium, a frequency offset detector detects a frequency offset using the split preamble.

Method of and apparatus for recording/reading information, circuit for recording/reading signal

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 unitand they are stored. Upon reproduction, in a white noise arithmetic operating unit, 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, an input signal (channel information) &#x39b;c(y|S) 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.

Information recording and reproducing apparatus and method and signal decoding circuit having improved noise processing characteristics

A data storage apparatus for magnetic recording and regeneration on a medium. Only in case of a dibit or Tri-bit code sequence in MTR codes having a restricted number of magnetic transition consecutive, a write unit records the interval of the magnetic transition on the medium with an extension of &Dgr;T relative to the original magnetic transition interval. For the maximum likelihood detection after equalization of the medium read signals, a read unit adds to an expected value of the maximum likelihood detection an amplitude error &Dgr;V arising from the extension record of the magnetic transition interval relative to the original magnetic transition interval. A parameter regulation unit regulates and sets &Dgr;T and &Dgr;V by use of test patterns.

Data storage apparatus and magnetic recording method

A detection circuit in a magnetic recording and playback apparatus which uses partial response and the maximum likelihood method, in which neither the size of the detection circuit nor the power consumption increase when the partial response order n increases. In this detection circuit, in the circuit that detects a signal read out from a head, either a plurality of equalizers for different target equalization waveforms, or a single variable target equalizer is provided. A detector for the waveform output from an equalizer is connected in series with the detector. A plurality of combinations, each formed by an equalizer and a detector, is connected in parallel to the output of a filter, the outputs of the combinations of equalizers and detectors being input to a switching circuit, which is controlled by a switching control means. The switching control means controls the switching circuit so that just one of the combinations of equalizer and detectors is selected as the detector output. If a variable target equalizer, which is capable of generating two or more different types of equalization waveforms, is used as the equalizer, it is possible to reduce the number of equalizers to one.

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Kawasaki, Japan

Takao Sugawara