Abstract: A method for recording/reproducing digital signals is provided in which each unit of digital data for each channel is constituted by m bit of standard data and n bits of expansion data, the data of each channel are separated into the above standard data and expansion data, the standard data and the expansion data are distributed to different recording tracks and a multiple track recording is performed by stationary heads, so that the data of each channel may be expanded and the m-bit standard data and the n-bit expasion data for each channel may be handled separately from each other.
Abstract: The channel characteristics of magnetic-disk storage devices vary with track radius. An adaptive three-tap transversal equalizer that compensates these variations for systems using partial-response signaling is presented. The equalizer coefficients are updated by applying a procedure that is related to the recursive least-squares algorithm. This new updating procedure does not require multiplications and is well suited for high-speed implementation. Results obtained by computer simulations and measurements with a prototype have shown that the proposed adaptive equalizer can effectively compensate variations in magnetic-disk channel characteristics with track radius.
June 28, 1989
Date of Patent:
October 22, 1991
International Business Machines Corporation
Francois B. Dolivo, Sedat Oelcer, Andreas Rungeler, Wolfgang H. Schott
Abstract: A signal recording/reproducing apparatus equipped with a recording head section for recording signals on a recording medium and a reproducing head section for reproducing the signals recorded on the recording medium. The recording head section is arranged to record the signal to form N recording sub-tracks on the recording medium and the reproducing head section has M reproducing sub-heads which trace the N recording sub-tracks to reproduce the recording signal. The pitch of the M sub-heads thereof is equal to a pitch of the recording sub-tracks and the number M of the sub-heads is greater than the number N of the recording sub-tracks. The reproducing head section is coupled to a reproduction signal detecting section which is turn eliminates the interference and the crosstalk between adjacent tracks from the reproduced signal due to the reproducing head section.
May 31, 1990
Date of Patent:
October 15, 1991
Matsushita Electric Industrial Co., Ltd.
Abstract: In order to avoid distortion of digital signals recorded on a magnetic tape following erasure of the recording tracks by a d.c. erase head, a compensating magnetic bias field opposed to the remanent erase field is superimposed upon the field recorded by the digital signals. This may be produced by superimposing a direct current on the recording current furnished to the recording head, either directly or by superimposing a bias voltage at the input of the recording amplifier. A separate magnetic head following the erase head and preceding the recording head may also be used to produce the compensating bias field.
Abstract: A cassette type recording unit comprises a cassette casing, an IC memory, a magnetism-electricity transducer capable of magnetically coupling to a recording/reproducing head of the magnetic tape recording apparatus, a recording system and a reproducing system which are arranged between the electro-magnetic transducer and the IC memory, a magnetic detector to detect magnetism in an erasing head of the magnetic tape recording apparatus and a semiconductor switching circuit for switching from the recording system to the reproducing system and vice versa on the basis of a signal from the magnetism detecting element.
Abstract: Two magnetic heads having different azimuth angles are mounted on a cylindrical rotary drum. The data is recorded on the magnetic tape by means of the magnetic heads mounted on the rotary drum. When recording, a frame is composed of one track formed by one magnetic head, and another track formed by the other magnetic head. The data is recorded in the unit of one frame. When reproducing, one track is read by one magnetic head, and the other track is read by the other magnetic head. Plural sets of data to compose one frame are stored in the memory, when reproducing in the normal direction, as the addresses are specified for each set of data. The data stored in the memory is read out from the memory as the addresses are specified so as to be output in a predetermined sequence.
Abstract: Apparatus, for preventing false recognition of one or more address marks arranged at predetermined locations in a stream of information-bearing bits played back from a record storage medium, such as a disk, includes a timer, synchronized with the bit stream, for defining a corresponding series of intervals or "windows" relating, respectively, to when each of the address marks is expected to occur in the bit stream. An decoder, responsive to the timer, signals which address mark is expected to occur during each interval defined by the timer. Validation circuitry, responsive to the bit stream, the timer and the decoder, determines whether each address mark expected actually occurs in the bit stream within the corresponding time interval defined by the timer.
Abstract: A magnetic recording and playback apparatus using a magnetic head disposed on a rotating drum for forming oblique recording tracks in succession on a magnetic tape to record or playback serial data along the same, has a tracking control for controlling the height of the magnetic head in the direction perpendicular to the length of the recording track. A speed control is included for controlling the rotating speed of the rotating drum and/or the traveling speed of the magnetic tape in accordance with the bit transfer rate of the serial data so that the magnetic tape travels one reference track pitch while the rotating drum makes an integer number of rotations. A processor is included for compressing the serial data along the time base so that the serial data is recorded while the magnetic head scans the recording track.
Abstract: A tape recording apparatus is capable of operation in either a normal recording mode or a high band recording mode. Detecting holes to indicate whether a tape cassette loaded into the recording apparatus is designed for the normal recording mode or the high band recording mode are formed in the tape cassette. The kind of cassette is detected from the detecting holes, and the high band recording mode or the normal recording mode is automatically set in accordance with the kind of tape cassette detected. The automatic setting can be selectively cancelled, however, in which case the recording can be executed in the normal recording mode even if a tape cassette designed for the high band recording mode has been loaded into the recording apparatus.
Abstract: A hard disk testing apparatus is comprised of a pair of carriages, each provided with a pair of upper and lower heads, and one of the upper and lower heads on either of the carriages is mounted on a micro adjustment carriage. With this structure, the head mounted on the fixed carriage writes a signal, and the head mounted on the carriage equipped with the micro adjustment carriage reads the signal. The structure and operation of the apparatus effectively prevent omission or duplication of testing tracks at the border between a test range of a hard disk covered by one of the pair of carriages and another test range covered by the other carriage.
Abstract: A method is disclosed for effecting update-in-place of data that has been recorded on tape in oblique tracks using a helical-scan recording technique. The data to be updated is recorded in a block of M tracks lying between first and second continuum each at least of N tracks where N is the worst-case number of tracks required to achieve head/track alignment. The block of M tracks comprises a first series of at least N tracks, a second series of tracks containing the data, and a third series of at least P tracks. When updating the data, the block is rewritten as a whole in a single continuum with the first track of the block being written within a distance of P tracks from the last track of the first continuum.
January 5, 1989
Date of Patent:
July 2, 1991
Hewlett-Packard Limited, Sony Corporation
Kentaro Odaka, Yoshizumi Inazawa, Brian A. Milthorp, Bruce A. Thompson
Abstract: A clock of a predetermined frequency is generated on a basis of clock information contained in a read signal. Sample values obtained by sampling the read signal in response to the clock are sequentially converted into digital data, and the thus obtained digital data are held in a first data holding means and then second data holding means in response to the clock for a time corresponding to the clock. The digital data and the output data from the second data holding means are added, and the addition output bits are multiplied by a predetermined constant by inserting a selected number of zero bits as upper significant bits, and shifting the addition output bits by the selected number of zero bits. Data corresponding to the difference between the multiplied output and the output of the first data holding means is obtained, and the thus obtained difference output is demodulated in response to the clock.
Abstract: A disk drive is configured for use in a data storage system of the type having a computer coupled to the disk drive for storing data on storage media in the disk drive and for retrieving data from the storage media in the disk drive. The storage media has a physical capacity. A plurality of first logical drive address parameters are received from the computer. Second drive address parameters are determined based on the first logical drive address parameters and the physical storage capacity of the storage media. The disk drive is controlled as a function of the first and second logical drive address parameters.
Abstract: A device for switching a coil between a first state where it is connected between a supply source and the ground through an impedance and a second state where it is connected between an output terminal and the ground, a first switch (T.sub.REC) being arranged between the output terminal and the supply source. This switching device comprises: a diode (14) connected between the output terminal (16) and the supply source, a controlled switch (T.sub.PB) connected in parallel with the impedance between a second terminal of the coil and the ground, and a detection and control means (20, 24) connected between the diode and the power supply source for detecting the time when the voltage between the diode and the ground becomes equal to a predetermined value lower than the forward voltage drop across the diode and for thereby controlling said switch.
Abstract: A switching circuit built in a record/playback mode switching circuit of a video tape recorder. Compulsory local overwriting can be executed while the playback of a recorded magnetic tape is under way. This allows characters, graphic information, VITC signal or similar multiplex signal carrying desired information to be recorded in the same manner as postrecording in a recorded magnetic tape which is being played back.
Abstract: A direct current restoration circuit in a digital VTR restores a low frequency component as a cut off in an input digital signal. The direct current restoration circuit has a feedback loop having variable gain. This gain is controlled according to a level of the signal obtained by adding an input signal and a signal as feed back. Therefore, the gain of the feedback loop can be precisely controlled irrespectively of wandering of the base line of the input signal. In addition, the feedback loop is cut off over a predetermined period including the time of switching of a magnetic head, so that waveform distortion at the time of switching can be prevented from being enlarged by the direct current restoration circuit. Additionally, the gain of the feedback loop is changed according to switching of the magnetic head, so that the low frequency component can be suitably compensated for each respective reproducing channel.