Abstract: A digital signal reproducing apparatus includes a reproducing circuit for reproducing from a recording medium a signal, whose amplitude takes on plural values, and which was recorded on the medium by digital modulation of a pilot signal component with digital data, a forming circuit for forming binary data indicative of the plural amplitude values, and a detecting circuit realized by binary data processing circuitry and detecting the pilot signal component on the basis of the binary data.

Abstract: A digital data reproducer, such as a VCR, reproduces digital data from a plurality of types of recording media. An equalizer includes a plurality of all-pass filters, for equalizing the reproduced digital data. A controller controls the equalization characteristics of the equalizer in accordance with the type of recording media, and controls the group delay characteristics of at least one of the plurality of all-pass filters. Thus, a single equalizer may be used for the plurality of types of recording media.

Abstract: In a magnetic disk apparatus using a composite thin-film magnetic head, high-speed reading and writing operations are achieved without increasing a read error rate and without decreasing a signal-to-noise ratio of read signals. The magnetic head is moved along an arc-like line on the magnetic disk having a track including a plurality of sectors. Each of the sectors has a data area and an identification area displaced from the data area due to movement of the magnetic head relative to the magnetic disk. A position identification sector which is positioned ahead of a target sector is determined based on a predetermined factor representing a period of time. An offset operation of the magnetic head is performed after the position identification sector is detected by a read head so that the magnetic head is moved from a first position to a second position.

Abstract: A digital signal recorder affixes m bits as a prefix to an input information word of n bits to be encoded into a channel word of n+m bits in parallel. The channel word is divided by a common divisor of the period of the channel word of n+m bits and the period of a pilot signal track pattern useful for read head tracking during playback of the recorded data, to form a series of channel word segments. Spectrum data for all possible values or bit patterns of the divided channel word segments, relative to the track patterns, are stored in look-up tables. The channel word having the frequency characteristic of the desired track pattern is selected by accessing the look-up table using the divided channel word (channel word segment) to provide address bits, so that the selected channel word can be processed, selected and recorded in real time.

Abstract: An amplifier for an MR head comprises a means for switching cut-off frequencies of a plurality of lowpass filters, when a data signal superposed by a disturbance signal (a composite signal) is input from an MR head, a means for extracting the disturbance signal from the composite signal, a means for adding the extracted disturbance signal to the composite signal. Accordingly, it possible to obtain a data signal less influenced and less distorted even if a disturbance signal appears.

Abstract: According to the present invention, an optical disk recording method for recording data on an optical disk including a land and a groove by forming a mark representing the data on the optical disk by irradiating a light beam onto the optical disk is provided. In this method, conditions for irradiating the light beam are varied depending upon whether a position at which the mark representing the data is formed on the land or on the groove so that a size of the mark formed on the land is equal to a size of the mark formed on the groove.

Abstract: A tape recording medium with slant tracks formed in two longitudinal areas above and below a center line on the recording medium, wherein the slant tracks each include subcode data at a midportion of each track with two control data areas on either side of the subcode and two data areas on the outboard sides of the control data areas. The data areas can include audio data, video data, or computer data or a mixture thereof and the control data provides information specifying the kind of digital data that is recorded for use in reproducing.

Abstract: Disclosed is a PRML regenerating apparatus for regenerating a signal read by a head from a storage medium. This PRML regenerating apparatus has a waveform equalizing circuit for waveform-equalizing the read signal, a maximum-likelihood decoder for maximum-likelihood-decoding, after obtaining a determination value by comparing the equalized output with upper and lower slice levels, this determination value and a control circuit for setting variable a distance between the upper slice level and the lower slice level of the maximum-likelihood decoder. The distance between the upper and lower slice levels can be thereby set variable in accordance with an equalization characteristic. A ternary determination circuit of the maximum-likelihood decoder is constructed of a memory for storing a correspondence table of the equalized output and the upper or lower slice level versus the determination result and the next upper or lower slice level.

Abstract: A digital data recording apparatus records digital data in tracks on a tape. Each track has a first signal area for storing track format information and a second signal area for storing a plurality of sync blocks. The apparatus includes a circuit for inserting, in the first signal area, regular TDS information indicating the track data structure of digital data, and a circuit for inserting, in the final sync block, backup TDS information having the same structure as the regular TDS information.

Abstract: Disclosed is a PRML regenerating apparatus for regenerating a signal read by a head from a storage medium. This PRML regenerating apparatus has a waveform equalizing circuit for waveform-equalizing the read signal, a maximum-likelihood decoder for maximum-likelihood-decoding, after obtaining a determination value by comparing the equalized output with upper and lower slice levels, this determination value and a control circuit for setting variable a distance between the upper slice level and the lower slice level of the maximum-likelihood decoder. The distance between the upper and lower slice levels can be thereby set variable in accordance with an equalization characteristic. A ternary determination circuit of the maximum-likelihood decoder is constructed of a memory for storing a correspondence table of the equalized output and the upper or lower slice level versus the determination result and the next upper or lower slice level.

Abstract: A head drum, as a first embodiment, for scanning a magnetic tape guided at an angle (.theta..sub.D) to the head drum assembly includes 2N number of video heads being divided into a first and a second groups, each group having N video heads being positioned closely adjacent one another at a predetermined space and the N video heads in the first group being positioned symmetrically opposite the N video heads in the second group along the rotating direction of the drum assembly, N being a positive integer. A second embodiment of a head drum for scanning a magnetic tape guided at an angle (.theta..sub.D) to the head drum assembly includes N pairs of video heads thereon, the N pairs of video heads being arranged in such a manner that each pair of video heads is angularly separated from one another by 360.degree./N. The angle (.theta..sub.D) of the first and the second embodiments to the head drum assembly is defined as: ##EQU1## wherein .theta..sub.

Abstract: A power source control circuit prevents a generation of a spark between a magnetic head and a magnetic disk by accurately controlling an electric potential provided to the magnetic head. A signal processing circuit provides to the magnetic head an intermediate electric potential between a positive source voltage and a negative source voltage supplied by a power source unit. A first circuit provides the positive and negative source voltages to the signal processing circuit. A second circuit controls one of the positive and negative source voltages in response to a reference voltage fed back from the signal processing circuit. The reference voltage is provided from the signal processing circuit to the magnetic head for setting the head at the intermediate electric potential.

Abstract: Separate servo parameter values are combined into a single servo parameter value having a bit length shorter than the total bit length of the separate parameter values. The combined parameter value is then stored in a servo field on a storage disk. By storing the shorter combined parameter, a given amount of servo information can be stored in a smaller space on the disk, thereby reducing overhead. In one embodiment, servo parameters are added together to create the combined parameters. In another embodiment, an equation is provided for creating the combined parameters, that results in a relatively large numerical distance between combined parameters in adjacent servo sectors on a track of the storage disk. The combined parameters stored on the disk can be used, for example, to check the accuracy of software position estimators in the disk drive.

Abstract: Two position signals N and Q having phases different by 90.degree. are demodulated from discrete readout signals of two-phase servo information through a position signal demodulating circuit. A level detecting circuit compares sizes of two position signals (absolute values) N and Q discretely available from the position signal demodulating circuit through seek operation at a certain speed. A cross-point C is calculated on the basis of two smaller discrete values Z and Y immediately prior to reversal of the size relationship of the two signals at the cross-point and a smaller discrete value X immediately after passage through the cross-point, and the thus calculated cross-point value C is set in an AGC amplifier as a reference amplitude value. The AGC amplifier adjusts the positional sensitivity to a certain value by amplifying the cross-point level of the two position signals N and Q so as to agree with the set reference amplitude value.

Abstract: A magnetic disc having a ROM area and a RAM area which are separated. The ROM only plane and the RAM only plane are separated on the magnetic disc.

Abstract: A position control method for use with a hard disk drive or other rotating body is provided. A radial position of a rotating body corresponding to an object to be controlled is detected as a current object position. Subsequently, a control operation signal is generated which is representative of a deviation between a target object position expressed in terms of the radial position of the rotating body and the current object position detected. In addition, an actuator manipulation-amount signal is output which is derived from the control operation signal. This actuator manipulation-amount signal is formed by selectively summing an integration signal with either a first or a second control signal. The first control signal is a function of the current object position. The second control signal is a function of a predicted object position at a second predetermined time after generation of the control operation signal.

Abstract: A magnetic disk drive capable of performing a head seek at high speed even when a track pitch of the recording track of the magnetic disk is narrowed. The structure eliminates incomplete erasure caused by a positioning error of a recording head and prevents side-fringe magnetic field from erasing a signal on an adjacent track in order to obtain a larger reproduction output.

Abstract: In accordance with the present invention, a method of intelligently organizing a magnetic storage medium is provided. The magnetic storage medium has free space and a plurality of files distributed thereon. The plurality of files includes volatile files created within a first predetermined period of time. First, the free space is substantially consolidated on the magnetic storage medium. Then, the volatile files are substantially positioned contiguous to the consolidated free space.

Abstract: A method for controlling speed of a spindle motor within a disk player is provided. The spindle motor drives a disk thereon and the disk player includes a pickup and a control circuit for performing focus and tracking operation of the pickup. The first step of method is to determine an allowable spin speed, Va, in accordance with a predetermined manner. The second step is to set speed of the spindle motor to operate at an allowable speed Va. The third step it to test if out-of-focus occurs during seeking of a particular track. If Yes in step 3, the fourth step is to re-focus the pickup. The fifth step is to set Va=Va- a predetermined decrement. The sixth step is to set speed of the spindle motor to operate at current Va decreased speed.

Abstract: A video cassette recorder includes a tape transport and servo that records digital data at one tape speed and plays back the digital data at one twentieth of the recording speed, both with a fixed speed of rotation of a drum head. On playback, each recorded segment of data on the tape is read from ten slightly different longitudinal positions on the magnetic tape, with the highest amplitude read-back signal being selected. The drum head comprises two playback heads that each have playback widths that are approximately twice as wide as each of four recording heads in the drum head.