Multi-frequency Patents (Class 360/43)
  • Patent number: 11473936
    Abstract: A signal processing circuit processes first to third detection signals output from a magnetic sensor device. The signal processing circuit includes a sphere information generation section that performs first processing and a determination section that performs second processing. With a set of values of the first to third detection signals at a certain timing taken as measurement data and with coordinates that represent the measurement data in an orthogonal coordinate system taken as a measurement point, the first processing includes determining center coordinates of a virtual sphere having a spherical surface approximating the distribution of a plurality of measurement data. The second processing includes determining whether four or more pieces of measurement data are suitable for use in the first processing.
    Type: Grant
    Filed: February 11, 2020
    Date of Patent: October 18, 2022
    Assignee: TDK CORPORATION
    Inventors: Shunji Saruki, Shinichirou Mochizuki
  • Patent number: 10147457
    Abstract: According to one embodiment, a magnetic disk device including a disk, a head configured to write write data to the disk, and a controller configured to write first data including a high-frequency pattern, detect, from a reproduced waveform obtained by reading the written first data, a difference between a first percentage by which high-frequency patterns of a first polarity are lost and a second percentage by which high-frequency patterns of a second polarity obtained by reversing the first polarity are lost, and adjust a high-frequency pattern of the first polarity of the write data or a high-frequency pattern of the second polarity of the write data on the basis of the difference.
    Type: Grant
    Filed: March 5, 2018
    Date of Patent: December 4, 2018
    Assignees: Kabushiki Kaisha Toshiba, Toshiba Electronic Devices & Storage Corporation
    Inventor: Tomokazu Okubo
  • Patent number: 9689683
    Abstract: A magnetic positioning device includes a magnetic scanning unit and a magnetic sensing unit. The magnetic scanning unit is for forming a first magnetic surface and a second magnetic surface. The first magnetic surface and second magnetic surface rotatably form a detection space. The magnetic sensing unit is disposed in the detection space for recording a first time point and a second time point. The magnetic sensing unit is in contact to the first magnetic surface at the first time point and defines a first-angle data. The magnetic sensing unit is in contact to the second magnetic surface at the second time point and defines a second-angle data. The first-angle data and the second-angle data define a location data of the magnetic sensing unit in the detection space with respect to the magnetic scanning unit, wherein the first time point is not the same as the second time point.
    Type: Grant
    Filed: November 20, 2015
    Date of Patent: June 27, 2017
    Inventors: Wei-Tung Chen, Yu Hsin Wang
  • Patent number: 9477681
    Abstract: Apparatus and methods for managing files among different zones of storage media in at least one non-volatile storage device. At least a first zone is associated with a first type of storage media and a second zone is associated with a second type of storage media. A file having at least one attribute is accepted with the at least one attribute describing a characteristic of the file. It is determined whether the at least one attribute meets an attribute criteria and the file is stored in the first zone and/or the second zone based on the determination of whether the at least one attribute meets the attribute criteria.
    Type: Grant
    Filed: August 4, 2015
    Date of Patent: October 25, 2016
    Assignee: Western Digital Technologies, Inc.
    Inventor: James N. Malina
  • Patent number: 9110133
    Abstract: A digital decoder, used in a reconfigurable circuit, for decoding digital pulses includes a phase indicator module having inputs coupled to a reference pulse input and a data pulse input. The phase indicator module has timing information outputs that provide logic values indicative of rising and falling edges of pulses occurring on the reference pulse input and the data pulse input. A phase decoder module has inputs coupled to the timing information outputs, and outputs decoded binary data values. In operation, the phase decoder module compares at least two of the logic values at the timing information outputs with a signal representative leading and trailing edges of a pulse applied to one of the phase inputs to determine a pulse arrival order sequence on the phase inputs and thereby provide the decoded binary data values.
    Type: Grant
    Filed: May 14, 2014
    Date of Patent: August 18, 2015
    Assignee: FREESCALE SEMICONDUCOTR, INC.
    Inventors: Ling Wang, Huangsheng Ding, Shayan Zhang, Wanggen Zhang
  • Patent number: 9001445
    Abstract: A data processing system includes a number of analog to digital converters operable to sample analog signals obtained from a magnetic storage medium to yield digital signals, multiple sync mark detectors operable to search for a number of different sync marks in the digital signals, and a sync mark detector output comparator operable to compare an output of each of the sync mark detectors to identify detection errors.
    Type: Grant
    Filed: December 13, 2013
    Date of Patent: April 7, 2015
    Assignee: LSI Corporation
    Inventors: Rui Cao, Haitao Xia, Lu Lu
  • Patent number: 8922927
    Abstract: A method for inhibiting cycle slip in a tape drive having at least three channels that each utilizes a corresponding numerically controlled oscillator includes establishing a reference clock that is based on an output of the numerically controlled oscillators for at least two of the channels, comparing the output of the numerically controlled oscillator for one of the three channels with the reference clock to determine a first channel phase delta value for the one channel, and generating an error signal for the one channel if the channel phase delta value exceeds a threshold phase delta value for the one channel.
    Type: Grant
    Filed: October 30, 2013
    Date of Patent: December 30, 2014
    Assignee: Quantum Corporation
    Inventors: James P. Peng, Jaewook Lee, Jerry Hodges, Turguy Goker
  • Patent number: 8885277
    Abstract: Technologies are described herein for implementing modulation coding schemes for TDMR. A data sequence is received to be stored on a first data track of a recording media. The first data sequence is encoded into a first codeword sequence using a modulation coding scheme, and the first codeword sequence is written to the first data track of the recording media. Subsequently, a second data sequence is received to be stored on a second data track of the recording media, the second data track being adjacent to the first data track. A second codeword sequence is generated for the second data sequence based on the first codeword sequence on the first data track, and the second codeword sequence is written to the second data track of the recording media.
    Type: Grant
    Filed: December 30, 2013
    Date of Patent: November 11, 2014
    Assignee: Seagate Technology LLC
    Inventors: Fatih Erden, Barmeshwar Vikramaditya, Deepak Sridhara, William Radich
  • Patent number: 8837070
    Abstract: A modulated signal of a predetermined frequency is applied to a capacitive sensor of a magnetic head. The capacitive sensor is located proximate to a media-facing surface of the magnetic head. A clearance between the magnetic head and a magnetic medium is determined using a response to the modulated signal at the predetermined frequency.
    Type: Grant
    Filed: April 22, 2013
    Date of Patent: September 16, 2014
    Assignee: Seagate Technology LLC
    Inventors: Michael Thomas Johnson, Pablo G. Levi
  • Patent number: 8837066
    Abstract: An apparatus comprises an alternating current coupling stage comprising a first filter configured to filter an analog signal to remove relatively low-frequency energy and read channel circuitry coupled to the alternating current coupling stage. The read channel circuitry comprises an analog-to-digital converter configured to convert the filtered analog signal to a digital signal, a detector configured to obtain a recovered signal using the digital signal, and a baseline correction module comprising a second filter and being configured to estimate a parameter of the first filter using a least mean squares algorithm based at least in part on the analog signal and an output of the second filter, adjust a parameter of the second filter based on the estimated parameter and add at least a portion of the removed relatively low-frequency energy to the digital signal by combining the output of the second filter and the digital signal.
    Type: Grant
    Filed: April 17, 2014
    Date of Patent: September 16, 2014
    Assignee: LSI Corporation
    Inventors: Jason D. Byrne, Scott M. Dziak
  • Patent number: 8699161
    Abstract: A hard disk drive or other disk-based storage device comprises a storage disk, a read/write head configured to read data from and write data to the disk, and control circuitry coupled to or otherwise associated with the read/write head. The control circuitry comprises a write driver configured to generate a write signal for data to be written to the storage disk, and a multiple-slope transition controller associated with the write driver and configured to control a data transition in the write signal such that the data transition comprises at least two different segments each having a different slope, with the transition controller comprising separate slope control mechanisms for each of the segments. By way of example, the data transition may comprise a dual-slope transition having first and second segments arranged sequentially between a start point and an end point of the data transition.
    Type: Grant
    Filed: March 9, 2012
    Date of Patent: April 15, 2014
    Assignee: LSI Corporation
    Inventors: Boris Livshitz, Jeffrey A. Gleason, Jason S. Goldberg, Paul Mazur, Cameron C. Rabe
  • Patent number: 8693121
    Abstract: A method includes designating a first sampling phase for a signal captured from a magnetic storage medium, where the signal is representative of information stored by the magnetic storage medium. The method further includes capturing a first waveform associated with the signal at the first sampling phase. The method also includes designating a second sampling phase different from the first sampling phase for the signal. The method further includes capturing a second waveform associated with the signal at the second sampling phase. The method also includes interleaving the first waveform and the second waveform to form an oversampled waveform. The first waveform and the second waveform are captured at a rate at least substantially equal to a rate at which the information stored by the magnetic storage medium was written to the magnetic storage medium.
    Type: Grant
    Filed: March 7, 2013
    Date of Patent: April 8, 2014
    Assignee: LSI Corporation
    Inventors: Bruce W. McNeill, Jason D. Byrne
  • Patent number: 8687303
    Abstract: SMR disk drives with hybrid E-regions that include a nonvolatile solid state memory E-region in addition to the magnetic media E-regions on disk are described. The memory E-region can be used in operations that will be referred as destaging and/or restaging to sequentialize sets of exception records to reduce the time and energy spent in executing seeks in the disk E-region. The ratio of the size of the solid state memory E-region to the total E-region capacity on the disks can be optimized for selected applications according to the invention using tradeoffs between performance and cost. For example, an embodiment with a memory E-region size that is 10% of the total disk E-region capacity achieves substantial performance enhancement over a disk-only E-region implementation and also results in smaller costs than would be required in a NAND-only memory E-region.
    Type: Grant
    Filed: March 2, 2012
    Date of Patent: April 1, 2014
    Assignee: HGST Netherlands B.V.
    Inventor: David Robison Hall
  • Patent number: 8681443
    Abstract: SMR disk drives with hybrid E-regions that include a nonvolatile solid state memory E-region in addition to the magnetic media E-regions on disk are described. The memory E-region can be used in operations that will be referred as destaging and/or restaging to sequentialize sets of exception records to reduce the time and energy spent in executing seeks in the disk E-region. The ratio of the size of the solid state memory E-region to the total E-region capacity on the disks can be optimized for selected applications according to the invention using tradeoffs between performance and cost. For example, an embodiment with a memory E-region size that is 10% of the total disk E-region capacity achieves substantial performance enhancement over a disk-only E-region implementation and also results in smaller costs than would be required in a NAND-only memory E-region.
    Type: Grant
    Filed: March 2, 2012
    Date of Patent: March 25, 2014
    Assignee: HGST Netherlands B.V.
    Inventor: David Robison Hall
  • Patent number: 8654467
    Abstract: A disk drive is disclosed comprising a disk including a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises a servo preamble. A head is actuated over the disk, wherein the head is operable to generate a read signal. The disk drive further comprises control circuitry including an analog cutoff filter operable to filter the read signal to generate a filtered read signal. The filtered read signal is sampled to generate read samples. During a normal operating mode, the analog cutoff filter is configured to have a first bandwidth. During a measurement mode, the analog cutoff filter is configured to have a second bandwidth greater than the first bandwidth, and the read samples representing at least part of the servo preamble are processed to measure a signal-to-noise ratio (SNR) and/or a fly height of the head.
    Type: Grant
    Filed: April 16, 2012
    Date of Patent: February 18, 2014
    Assignee: Western Digital Technologies, Inc.
    Inventors: Wai Ee Wong, Xiaotian Xu, Jinchuan Zheng, Guoxiao Guo, Jie Yu
  • Patent number: 8522067
    Abstract: A variable latency interface and method for managing variable latency. An apparatus includes a storage device controller and a read/write channel coupled to the storage device controller by a variable latency interface. The variable latency interface includes a media control component configured for read and write operations. The variable latency interface also includes a data transfer component configured for read and write operations. A read or write operation in the media control component is offset from a respective read or write operation in the data transfer component by a latency period.
    Type: Grant
    Filed: October 15, 2010
    Date of Patent: August 27, 2013
    Assignee: STMicroelectronics, Inc.
    Inventor: Cecilia Ozdemir
  • Patent number: 8184390
    Abstract: Data is processed by receiving data having a value. The amplitude of the received data is adjusted using the processor based at least in part on the value of the received data to obtain modified data.
    Type: Grant
    Filed: November 23, 2009
    Date of Patent: May 22, 2012
    Assignee: Link—A—Media Devices Corporation
    Inventors: Haitao Xia, Yenyu Hsieh
  • Patent number: 8139305
    Abstract: Various embodiments of the present invention provide systems and methods for acquiring timing and/or gain information. For example, various embodiments of the present invention provide data processing circuits that include a sample splitting circuit, a first averaging circuit, a second averaging circuit and a parameter calculation circuit. The sample splitting circuit receives a data input that includes a series of samples that repeat periodically over at least a first phase and a second phase. The sample splitting circuit divides the series of samples into at least a first sub-stream corresponding to the first phase and a second sub-stream corresponding to the second phase. The first averaging circuit averages values from the first sub-stream to yield a first average, and the second averaging circuit averages values from the second sub-stream to yield a second average. The parameter calculation circuit calculates a parameter value based at least in part on the first average and the second average.
    Type: Grant
    Filed: September 14, 2009
    Date of Patent: March 20, 2012
    Assignee: LSI Corporation
    Inventors: George Mathew, Hongwei Song, Yuan Xing Lee
  • Patent number: 7742250
    Abstract: The present disclosure is directed to spectral analysis of a position error signal. In a particular embodiment, the method includes analyzing a spectral content of a position error signal. The method also includes comparing the spectral content to a threshold. Further, the method includes determining a result based on the comparing the spectral content to the threshold. In another particular embodiment, the spectral content of the position error signal is determined by performing a discrete fourier transform (DFT) on the error signal, determining a magnitude of the DFT output, and low pass filtering the magnitude.
    Type: Grant
    Filed: January 12, 2007
    Date of Patent: June 22, 2010
    Assignee: Seagate Technology LLC
    Inventors: Jeff Nelson, Farhad Navid, Richard Martin, Anton Viktorovich Goldade
  • Publication number: 20080266695
    Abstract: A magnetic sensor control device has an input section, a selection section, a calculation section, and a setting section. The input section inputs a plurality of magnetic data each having 3 components sequentially output from a 3-dimensional (3D) magnetic sensor. The selection section selects 4 magnetic data satisfying a predetermined 4-point selection condition from the plurality of the input magnetic data. The calculation section calculates a center point equally distant from 4 points corresponding to the 4 selected magnetic data. The setting section sets 3 components representing the center point as an offset of the magnetic data.
    Type: Application
    Filed: June 27, 2008
    Publication date: October 30, 2008
    Applicant: YAMAHA CORPORATION
    Inventor: Ibuki Handa
  • Patent number: 7302749
    Abstract: The method of making a two-layer lap winding (12) for a multiphase electrical machine includes the steps of winding a first coil unit (20) of a first phase winding (14) around a winding bar (10); subsequently laying a coil connector (18) of the first phase winding (14) in a first direction and then winding at least one other coil unit (16) of at least one other phase winding (14) around the winding bar (10) and over the coil connector (18). Subsequently a second coil unit (22) of the first phase winding (14) is wound around the winding bar (10) following all first coil units of all phase windings and after all coil connectors from the first coil units are laid. A method of making a stator from the two-layer lap winding (12) is also described.
    Type: Grant
    Filed: May 10, 2004
    Date of Patent: December 4, 2007
    Assignee: Robert Bosch GmbH
    Inventors: Helmut Kreuzer, Eberhard Rau, Reinhard Bezner
  • Patent number: 6894855
    Abstract: A disk drive of perpendicular magnetic recording method including a read head comprising a GMR element and a drive using a double-layered disk medium, is disclosed. In the magnetic field response characteristic of the GMR element, the relationship between the degree of nonlinearity and a pulse width at 50% threshold (PW50) of a differentiated read signal is used. The degree of nonlinearity of the GMR element is adjusted such that the PW50 is smaller than the maximum value. The read channel comprises a differentiation circuit for converting the read signal output from the GMR element into the differentiated read signal.
    Type: Grant
    Filed: August 27, 2002
    Date of Patent: May 17, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yuka Aoyagi, Akihiko Takeo
  • Patent number: 6647445
    Abstract: The present invention provides for the compression of digital and analog data for storage and transmission. Analog data in the form of an analog signal is converted into a digital signal by an analog-to-digital converter. The digital signal is then converted into an analog signal having an alternating frequency by a first converter processor and an alternating frequency generator according to a predetermined conversion table. To reproduce the original analog signal, the analog signal having an alternating frequency is first converted back into a digital signal by an alternating frequency measurement means connected to a second converter processor, also in accordance with the predetermined conversion table. The digital signal is then converted to the original analog signal by a digital-to-analog converter.
    Type: Grant
    Filed: April 23, 2002
    Date of Patent: November 11, 2003
    Inventor: Eugene Rzyski
  • Patent number: 6476743
    Abstract: A method for decoding information contained in a waveform having a series of peaks is disclosed which is particularly directed to a method for reading a magnetic stripe for example on a card that allows the information on the stripe to be read without the need for unidirectional, single stroke swiping motion of the stripe. Features are disclosed that permit the accurate decoding of magnetic stripe data to define the bi-phase coded bits in the presence of signal degradations caused specifically, but not exclusively, by variations in the read speed including stop events and reversals. The method uses sampling of the waveform at a variable rate based upon the area of the waveform. The samples are used to locate peaks in the waveform, the profiles of which are then compared using various criteria with trained model peaks to classify the peaks into different types based upon the intersection between the different bits allowed under the bi-phase coding rules.
    Type: Grant
    Filed: November 9, 2001
    Date of Patent: November 5, 2002
    Assignee: Iders Incorporated
    Inventors: Bradley Dale Brown, Shamir Nizar Mukhi
  • Patent number: 6124993
    Abstract: A digital servo track pattern for a magnetic medium which can be recorded and reproduced by a recording and reproducing system. The servo track pattern has a plurality of digital mark patterns recorded thereon, each of said digital mark patterns having a leading identifier field of digital bits, a trailing identifier field of digital bits and a field of digital synchronizing data located between said leading and trailing identifier fields. The leading identifier field of digital bits is electrically equivalent during reproducing while the medium is moving in a first direction to the trailing identifier field of digital bits while the medium is moving in a direction opposite to said first direction.
    Type: Grant
    Filed: May 20, 1994
    Date of Patent: September 26, 2000
    Assignee: Ampex Corporation
    Inventor: Kurt F. Hallamasek
  • Patent number: 6021281
    Abstract: A recording device for recording film information concerning photography made to each of a plurality of exposure areas on respective recordable areas corresponding to the plurality of exposure areas, includes: a film feeder which feeds the film; a recording head which records a film information signal on a corresponding recordable area, the signal having a specified frequency; and a frequency controller which changes the signal frequency during the time when the film information is being recorded on the recordable area. The recording device makes it possible to simplify the construction of a camera, and to record film information with high density and stability.
    Type: Grant
    Filed: April 22, 1998
    Date of Patent: February 1, 2000
    Assignee: Minolta Co., Ltd.
    Inventors: Yoshiharu Tanaka, Junichi Tanii
  • Patent number: 5623376
    Abstract: A digital information restoring device is arranged to detect time between level transition points of a digital signal which indicates digital information by means of variations in its period, output the resultant period data, calculate an average value of at least two period data among the output period data, and compare the average value with the aforesaid period data, and restore the digital information. The digital information restoring device is, therefore, capable of restoring the digital information at a high speed without using a high-speed PLL circuit or the like. The digital information restoring device may also be arranged to perform time-axis expansion of only part of the received period data, and input the resultant period data to a computing circuit to restore the digital information.
    Type: Grant
    Filed: April 26, 1994
    Date of Patent: April 22, 1997
    Assignee: Canon Kabushiki Kaisha
    Inventors: Shingo Ikeda, Shinichi Yamashita
  • Patent number: 5466920
    Abstract: Real time decoding methods and apparatus for a card transaction terminal used for reading a magnetic stripe on a data card. The method is implemented in a microcomputer employed in the terminal. The data decode method for the microcomputer decodes data in real time as it is read from the magnetic stripe on the card and obviates random access memory external to the microcomputer. A memory is provided in the terminal large enough to store data characters corresponding to at least one predetermined data field on the card generated during a swipe of the card but insufficient to store all of the self clocking signals generated during the swipe. A sentinel character in the self clocking signals is first decoded. Then, a data character associated with the at least one predetermined data field is decoded in response to a predetermined number of self clocking signals generated subsequent to the sentinel character. Finally, the decoded data character is stored in the memory.
    Type: Grant
    Filed: November 8, 1991
    Date of Patent: November 14, 1995
    Assignee: MicroBilt Corporation
    Inventors: Parameswaran B. Nair, Kumar S. Choudhuri, James T. Stills, John C. Evans
  • Patent number: 5453603
    Abstract: A method and apparatus are provided for decoding bi-phase encoded data. The apparatus performs the steps of establishing a predicted bit cell length for a bit cell, detecting a leading clocking edge transition of the bit cell, detecting a first edge transition after the leading clocking edge transition, and calculating a first time interval from the leading clocking edge transition to the first detected edge transition.
    Type: Grant
    Filed: January 4, 1994
    Date of Patent: September 26, 1995
    Assignee: Best Lock Corporation
    Inventors: Roger K. Russell, Mark W. Voth
  • Patent number: 5396370
    Abstract: A process of scanning and evaluating binary data stored on a magnetic track of a magnetic storage card includes a calibration at the beginning of the scanning operation with certain information stored on the card and a determination of a calibrated time interval. A time curve of the output signal in the calibrated time interval is registered and compared to predefined curve patterns in order to determine deviation of the registered time curve from the curve patterns. A curve pattern showing a least deviation from the registered time curve is identified. The curve pattern may be selected on the basis of information obtained from a previously determined output signal curve. Also, the extreme values are detected to obtain information stored on the card.
    Type: Grant
    Filed: October 21, 1993
    Date of Patent: March 7, 1995
    Assignee: Siemens Nixdorf Informationssysteme AG
    Inventors: Hubert Behr, Wolfgang Fick, Waldemar Jager
  • Patent number: 5305156
    Abstract: A hard disk drive is disclosed wherein data is so recorded on the disk that a transducer puts out a waveform having a positive peak followed by a negative peak for each bit representative of a logic one of the data. For eliminating the read error that will arise when the disk is accidentally magnetized on its track gaps or other regions which should have been left unmagnetized, a read circuit connected to the transducer is constructed to recreate the recorded data by detecting the negative peaks, instead of the positive peaks, of the transducer output waveform.
    Type: Grant
    Filed: October 14, 1992
    Date of Patent: April 19, 1994
    Assignee: TEAC Corporation
    Inventor: Masao Takei
  • Patent number: 5229894
    Abstract: In a method and apparatus for decoding data recorded on magnetic storage medium such as a "swipe card" to yield decoded data values, a magnetoresistive sensor is used to read the data as a pulse stream from the medium and to measure the widths of the received pulses. The data is preferably stored in the medium by the technique of two-frequency phase coherent recording (F2F). By comparing the widths of pulses to be decoded with the widths of previously read pulses to which data values have already been allocated circuitry for derivin a clock signal from a self-clocking recorded signal can be dispensed with. Pulse widths may be measured by monitoring the output of counters (20) incremented by a fast clock for the duration of each pulse, and the pulse widths are compared by comparing counter outputs stored in a memory (28) using a microprocessor (26).
    Type: Grant
    Filed: December 13, 1991
    Date of Patent: July 20, 1993
    Assignee: M.R. Sensors Limited
    Inventors: Alan J. Collins, Selvaratnam
  • Patent number: 5130863
    Abstract: In a digital signal recording apparatus it is possible to input plural kinds of digital information signals having different bit rates from one another. Recording is performed for each data block which includes a predetermined amount of data which includes main data corresponding to the digital information. The ratio of the main data within the data block is switched in accordance with each kind of digital information signal.
    Type: Grant
    Filed: March 28, 1989
    Date of Patent: July 14, 1992
    Assignee: Canon Kabushiki Kaisha
    Inventors: Shinichi Yamashita, Kenichi Nagasawa, Tomohiko Sasatani, Toshihiro Yagisawa
  • Patent number: 5128809
    Abstract: Methods and circuitry for generating sector and data cell timing frequencies for banded variable frequency sector disc drive systems with dedicated plus embedded servo positioning systems which have the timing signals synchronized to servo track information written on a dedicated surface of the disc.
    Type: Grant
    Filed: June 29, 1989
    Date of Patent: July 7, 1992
    Assignee: Digital Equipment Corporation
    Inventors: Michael D. Leis, Robert Y. Noguchi, Joseph M. Rinaldis, Robert A. Rubke
  • Patent number: 5003408
    Abstract: The specification discloses means for correcting timing variations present in a data stream emanating from a data storage device such as a magnetic tape drive or the like before the data stream is applied to the data separator or other such input device of a computer. This is accomplished by remodulating the time-varying bits in the data stream in a manner which reduces or eliminates the undesired timing variations. Basically, the system utilizes frequency-modulation techniques to in effect remodulate the raw data stream. The application discloses, as one preferred embodiment, a pulse-width modulator which receives the error signal output of a phase-locked loop network, the input of the pulse-width modulator being coupled to the incoming raw data stream.
    Type: Grant
    Filed: August 4, 1988
    Date of Patent: March 26, 1991
    Assignee: Irwin Magnetic Systems, Inc.
    Inventors: Richard A. Farkas, Marlin K. Klumpp, Michael L. Bolt, Housan Dakroub
  • Patent number: 4987500
    Abstract: The present invention utilizes a dual frequency data writing scheme. At a first frequency, flux transitions are achieved which result in large excursions of the information signal. In the preferred embodiment, the first frequency approximates the maximum frequency at which such excursions can occur. A second higher frequency is utilized to create the very small or no excursions. At this second higher frequency, a complex flux transition is not achieved. Therefore, there is little or no information signal. Information is represented by the presence or absence of excursions. In the preferred embodiment, the first frequency is approximately 33,000 flux changes per inch, and the second frequency is approximately 67,000 flux changes per inch. In order to detect data written by the present scheme, an adaptive, self-compensating scheme is utilized. The present invention utilizes an excursion detection scheme which is pattern and radii independent.
    Type: Grant
    Filed: November 14, 1988
    Date of Patent: January 22, 1991
    Assignee: Brier Technology, Inc.
    Inventors: John Bizjak, Michael Hassel, David Niemann
  • Patent number: 4876615
    Abstract: A data decoding system for decoding a digital signal stored on a magnetic medium so that one of logical variables "1" and "0" is indicated by a state inversion of signals "H" and "L" at a time interval of a bit cell period, while the other logical variable is indicated by the state inversion at a time interval of half of the bit cell period, wherein a reproduction processing signal is produced having the signal state varying only in response to the state inversion corresponding to one of the logical variables and an NRZ signal is formed by exclusive logical addition of the reproduction processing signal and a delay signal delaying the reproduction processing signal for a time interval of one bit cell period.
    Type: Grant
    Filed: October 30, 1987
    Date of Patent: October 24, 1989
    Assignee: Nakamichi Corporation
    Inventor: Tadaaki Chikashige
  • Patent number: 4837782
    Abstract: In a digital communication system, a CMI (Coded Mark Inversion) decoder for extracting an optimum sampling timing from a CMI coded input signal so as to NRZ (Non-Return to Zero) format the input signal. A circuit for producing clock signals which are individually deviated in phase by +1/4 and -1/4 of a period relative to a reference clock signal that is extracted from the input signal is constituted by a logic circuit.
    Type: Grant
    Filed: April 14, 1988
    Date of Patent: June 6, 1989
    Assignee: NEC Corporation
    Inventor: Eisaku Sasaki
  • Patent number: 4821293
    Abstract: A digital phase locked loop (PLL) circuit having an input terminal to which an input digital signal is supplied, a counter for counting a reference clock, a digital phase comparator for comparing the phases of the input digital signal and the output of the counter, a digital low-pass filter supplied with the output of the digital phase comparator, a correction control signal generating circuit and a control circuit, whereby the quantization error is reduced to improve the follow-up characteristic of the digital PLL circuit. Also, the digital PLL circuit contains no residual phase error and this highly-stable digital PLL circuit is arranged so as not to respond to a high frequency fluctuation component such as a peak shift.
    Type: Grant
    Filed: May 11, 1988
    Date of Patent: April 11, 1989
    Assignee: Sony Corporation
    Inventors: Kazutoshi Shimizume, Mutsumi Kimura
  • Patent number: 4809304
    Abstract: The invention relates to a method for extracting a synchronous clock signal from a single- or double-density coded signal via a modulation frequency corresponding to the time interval T separating the most closely-spaced pulses of the received signal. This clock signal comprises a window that makes it possible to extract a binary data signal from the coded signal that is received; the values of the binary data signal have determinate durations T or 2T. The invention also relates to an apparatus for performing the method.
    Type: Grant
    Filed: March 17, 1986
    Date of Patent: February 28, 1989
    Assignee: Bull, S. A.
    Inventor: N. Vo Chau
  • Patent number: 4809301
    Abstract: A bi-phase signal detection apparatus having a milti-tapped delay line to delay a coded input signal. A polarity change in the input signal loads the signal on each delay tap into a parallel shift register. A subsequent delayed polarity change will apply the shift register signals into the decode logic circuit which determines the output signals.
    Type: Grant
    Filed: November 25, 1987
    Date of Patent: February 28, 1989
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventor: Melvin H. Rhodes
  • Patent number: 4714968
    Abstract: A digital apparatus for data recovery system wherein data is recorded in FM or MFM code on magnetic media, comprises a measuring unit that in correspondence of a read pulse n as an input, supplies as an output, information related to the actual duration of interval N between pulse n and the previous read pulse n-1. A recovery unit for the magnetic media speed error relative to a nominal speed corrects the duration according to a code representative of the magnetic media speed error and a peak shift recovery unit which, according to the peak shift of pulse n-1, determined on the basis of the time history of the most recent pulses n-2, n-3, n-1 and the corrected duration, supplies as an output, nominal duration information related to this corrected duration and information representative of the direction and the amount of the peak shift of said read out pulse N-7.
    Type: Grant
    Filed: March 3, 1986
    Date of Patent: December 22, 1987
    Assignee: Honeywell Information Systems Italia
    Inventor: Bonifacio Troletti
  • Patent number: 4672483
    Abstract: An information recording and reading apparatus for a recording medium, such as a magnetic disc or optical disc, which operates under the control of a central controller. The information recorded in the medium is stored in a memory and checked for errors during a time period subsequent to the recording operation by reading the recorded data in a read-after-write process. A comparator compares the content of the memory and the read-after-write signal to determine whether an error has occurred. If an error is detected, the data is re-recorded in a different part of the recording medium.
    Type: Grant
    Filed: July 3, 1985
    Date of Patent: June 9, 1987
    Assignee: NEC Corporation
    Inventor: Michitaka Kawada
  • Patent number: 4651328
    Abstract: Arrangement for supervising a CMI-code converter in a PCM-multiplex transmission system, in which a binary signal is converted into a CMI-signal or vice versa, the code converter having a first terminal for the CMI-signal and a second terminal for the binary signal, characterized in that the first input of the code converter is connected to a first input of a modulo-2 divider and also via a delay element to a second input of a modulo-2 divider, that the output of the modulo-2 divider is connected to a first input of a summing device, that the second terminal of the decoder unit is connected to a second input of the summing device and that the supervising signal is produced at the output of the summing device.
    Type: Grant
    Filed: November 4, 1985
    Date of Patent: March 17, 1987
    Assignee: U.S. Philips Corporation
    Inventors: Cornelis J. den Hollander, Geert Winters
  • Patent number: 4628372
    Abstract: Program segments on a magnetic tape are identified by recording patterns of continuous sine wave signal bursts and blank portions in non-recorded spaces between the program segments, the continuous sine waves all having the same low-frequency relative to the audio frequency band and a selected number of continuous sine waves and a corresponding blank portion of the same length each form one level of a binary signal and a second burst of continuous sine waves and a corresponding blank portion of the same length each form the other level of the binary signal. These four elements are arranged to provide an individual address code for each of the program segments on the magnetic tape and are arranged such that they may be read in either direction of tape travel, in order to identify the program segment from either direction, by forming the address code signals as complementary pairs based upon the location of the program segments relative to the ends of the tape.
    Type: Grant
    Filed: July 20, 1984
    Date of Patent: December 9, 1986
    Assignee: Sony Corporation
    Inventor: Takashi Morisawa
  • Patent number: 4553177
    Abstract: In the recording of information signals the signal elements of which are to have a prescribed length, a read/write head (WRT) is used in which the write gap (W1) is at a distance from the read gap (R) corresponding to the prescribed length. When a signal edge occurs at the read gap (R), an evaluation circuit (FIG. 4) controls the write gap (W1) in such a way that the latter records the next signal edge. For recording by the NRZ process, a further write gap (W2) can be provided between the write gap (W1) and the read gap R, which is controlled like the first and makes possible the recording of binary signals.
    Type: Grant
    Filed: November 9, 1983
    Date of Patent: November 12, 1985
    Assignee: Nixdorf Computer AG
    Inventor: Peter Scholich
  • Patent number: 4532559
    Abstract: Apparatus is disclosed for reading phase encoded digital data from a nine-track magnetic tape which apparatus includes timing circuitry for deriving a clock signal from the recorded data. A portion of the timing circuitry is associated with each track on the tape and automatically accommodates, without generating errors, phase changes in the derived clock signal in that track caused by speed variations in the magnetic tape transport and due to bit shifts caused by certain data patterns.Tape transport speed variations are sensed and the derived clock rate is corrected by a digital phase-locked loop which uses a counter that is clocked at a constant rate to determine the timing "window" during which the circuitry looks for signal transitions on the magnetic tape. A running average of the count remaining in the counter at the time when a transition actually occurs is used to adjust the counter starting value until equilibrium is established.
    Type: Grant
    Filed: February 14, 1983
    Date of Patent: July 30, 1985
    Assignee: Prime Computer, Inc.
    Inventors: Charles C. Long, David M. Lounsbury, Richard R. Curtin
  • Patent number: 4503472
    Abstract: An encoder/decoder is described which allows data transmission on an A.C. coupled transmission system. The encoder converts a serial data stream comprised of combinations of logical "1"'s and "0"'s in an NRZ format to an output pulse train. The latter is characterized not only by phase reversal for each bit of data, as required for A.C. coupled systems, but by bit durations which are dissimilar for a logic "1" and "0". The encoded data is transmitted and subsequently applied to the decoder which restores the data to an NRZ format, and provides a corresponding series of clock pulses for interpreting the data. The encoder/decoder may be implemented in a simple logic configuration.
    Type: Grant
    Filed: September 1, 1983
    Date of Patent: March 5, 1985
    Assignee: Burroughs Corp.
    Inventor: William A. Lacher
  • Patent number: 4481549
    Abstract: A circuit is provided for encoding digital data to be recorded on high-density magnetic storage media. The circuit converts serial data to modified phase modulation encoded serial data with time encoding or write precompensation.
    Type: Grant
    Filed: December 22, 1980
    Date of Patent: November 6, 1984
    Assignee: Tektronix, Inc.
    Inventor: John G. Theus
  • Patent number: 4473851
    Abstract: Digital data is recorded onto a cassette tape by utilizing an audio cassette tape recorder under the control by a microprocessor. The microprocessor assigns "0" digital data bit a time sequence of a shorter pulse of a single period (T.sub.1) and having a duty cycle of 50% and a longer pulse of a single period (T.sub.2) and having a duty cycle of 50%. Assigned to "1" data bit is a time sequence of a single period of T.sub.2 pulse and a single period of T.sub.1 pulse. An analog signal applied to the recording unit of the audio cassette tape recorder initiates a gradual increase in its level at a point of transition from the low level L to the high level H of either T.sub.1 or T.sub.2 pulse, and returns to a start level at a point of transition from the H to the L level and also initiates a gradual decrease in the level. In this manner, a waveform conversion is performed.
    Type: Grant
    Filed: February 22, 1982
    Date of Patent: September 25, 1984
    Assignee: Aisin Seiki Kabushiki Kaisha
    Inventors: Nobuyoshi Nagura, Taneichi Kawai