Fujitsu Corporation

Kiichiro Kasai

Hiroshi Uno

Nobuyoshi Yamasaki

Toshiki Kimura

A partial response is utilized to record information on a medium and then regenerate the information from the medium. A regenerating system undergoes equalization including subjecting a regeneration signal from the medium to the convolution of(k&#x2212;s&#xb7;D) Such convolution is performed in the regenerating system so that low-frequency band noises are reduced with an improved error rate. The information is decoded from the equalized signal by use of maximum-likelihood detection.

Signal processing method, signal processing circuit and information recording/regenerating apparatus

A partial response is utilized to record information on a medium and then regenerate the information from the medium. A regenerating system undergoes equalization including subjecting a regeneration signal from the medium to the convolution of(k&#x2212;s&#xb7;D)

A positioning method and a positioning device are disclosed for controlling an actuator and moving it to a target position. The positioning method generates a random wave signal RN and detects a position error from the target position. The servo control signal CV is generated to position the actuator back to the target position, and the random wave signal RN is added to the servo control signal CV to generate a control signal. Since a random, minute vibration is constantly applied to the actuator to avoid the assumption of a static state by bearings of the actuator, the actuator is affected only by dynamic friction, and relative to the control value, its movement is representative of a linear characteristic. As a result, the positioning accuracy is enhanced, and since the random wave is employed, there is no deterioration of the positioning accuracy of the servo system.

Positioning method, positioning device and disk device

An information storage apparatus for carrying out a signal processing for a partial response system through a recording medium. A recording unit converts an RZ input code into an NRZI code and records the NRZI code in the recording medium through a write head, thereby giving a (1&minus;D) waveform processing to the RZ input code. An equalizing unit carries out Nyquist equalization for a reproduction code reproduced from the recording medium through a read head based on an equalizing transmission characteristic obtained by dividing a cosine roll-off characteristic setting &frac14; of a maximum frequency determined by the RZ input code to be a Nyquist frequency by a transmission characteristic of a magnetic recording and reproducing system. A maximum likelihood detecting section carries out maximum likelihood detection for the code string which is Nyquist equalized by the equalizing section.

Narrow band partial response signal processing apparatus, signal processing method and information storage apparatus

A signal processing apparatus in which a signal is processed using a partial response method is provided. The apparatus includes a signal processing unit which performs an operation (1&minus;D) on each bit of an input code, where D indicates a delay of one bit; an equalizing unit which equalizes a bit sequence processed by the signal processing unit to a Nyquist characteristic; and a maximum likelihood detection unit which detects a maximum likelihood bit sequence from the bit sequence equalized by the equalizing unit. The input code of the signal processing unit is a 1/7-conversion RLL code of input data.

Signal processing apparatus utilizing a partial response method, and signal processing method, information recording apparatus, and information reproduction apparatus therefore

A magnetic disk reproducing apparatus for reproducing data recorded at an arbitrary position on a rotating disk by a head includes a level detecting unit for detecting a level of a DC component of a reproduced signal outputted from the head; a delaying unit for delaying the reproduced signal by a predetermined value; and a correcting unit for correcting the level of the DC component of the reproduced signal outputted from the delaying unit when the level of the DC component detected by the level detecting unit becomes larger than a predetermined threshold level. Preferably, a control method of a magnetic disk reproducing apparatus having such a construction includes the steps of detecting a level of a DC component of a reproduced signal outputted from the head; delaying the reproduced signal by a predetermined value; and correcting the level of the DC component of the delayed reproduced signal when the level of the DC component so detected becomes larger than a predetermined threshold level.

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Kawasaki, Japan

Kiichiro Kasai