Multi-frequency Patents (Class 360/43)
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Patent number: 11473936Abstract: 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: GrantFiled: February 11, 2020Date of Patent: October 18, 2022Assignee: TDK CORPORATIONInventors: Shunji Saruki, Shinichirou Mochizuki
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Patent number: 10147457Abstract: 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: GrantFiled: March 5, 2018Date of Patent: December 4, 2018Assignees: Kabushiki Kaisha Toshiba, Toshiba Electronic Devices & Storage CorporationInventor: Tomokazu Okubo
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Patent number: 9689683Abstract: 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: GrantFiled: November 20, 2015Date of Patent: June 27, 2017Inventors: Wei-Tung Chen, Yu Hsin Wang
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Patent number: 9477681Abstract: 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: GrantFiled: August 4, 2015Date of Patent: October 25, 2016Assignee: Western Digital Technologies, Inc.Inventor: James N. Malina
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Patent number: 9110133Abstract: 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: GrantFiled: May 14, 2014Date of Patent: August 18, 2015Assignee: FREESCALE SEMICONDUCOTR, INC.Inventors: Ling Wang, Huangsheng Ding, Shayan Zhang, Wanggen Zhang
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Patent number: 9001445Abstract: 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: GrantFiled: December 13, 2013Date of Patent: April 7, 2015Assignee: LSI CorporationInventors: Rui Cao, Haitao Xia, Lu Lu
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Patent number: 8922927Abstract: 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: GrantFiled: October 30, 2013Date of Patent: December 30, 2014Assignee: Quantum CorporationInventors: James P. Peng, Jaewook Lee, Jerry Hodges, Turguy Goker
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Patent number: 8885277Abstract: 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: GrantFiled: December 30, 2013Date of Patent: November 11, 2014Assignee: Seagate Technology LLCInventors: Fatih Erden, Barmeshwar Vikramaditya, Deepak Sridhara, William Radich
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Patent number: 8837070Abstract: 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: GrantFiled: April 22, 2013Date of Patent: September 16, 2014Assignee: Seagate Technology LLCInventors: Michael Thomas Johnson, Pablo G. Levi
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Patent number: 8837066Abstract: 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: GrantFiled: April 17, 2014Date of Patent: September 16, 2014Assignee: LSI CorporationInventors: Jason D. Byrne, Scott M. Dziak
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Patent number: 8699161Abstract: 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: GrantFiled: March 9, 2012Date of Patent: April 15, 2014Assignee: LSI CorporationInventors: Boris Livshitz, Jeffrey A. Gleason, Jason S. Goldberg, Paul Mazur, Cameron C. Rabe
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Patent number: 8693121Abstract: 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: GrantFiled: March 7, 2013Date of Patent: April 8, 2014Assignee: LSI CorporationInventors: Bruce W. McNeill, Jason D. Byrne
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Patent number: 8687303Abstract: 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: GrantFiled: March 2, 2012Date of Patent: April 1, 2014Assignee: HGST Netherlands B.V.Inventor: David Robison Hall
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Patent number: 8681443Abstract: 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: GrantFiled: March 2, 2012Date of Patent: March 25, 2014Assignee: HGST Netherlands B.V.Inventor: David Robison Hall
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Patent number: 8654467Abstract: 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: GrantFiled: April 16, 2012Date of Patent: February 18, 2014Assignee: Western Digital Technologies, Inc.Inventors: Wai Ee Wong, Xiaotian Xu, Jinchuan Zheng, Guoxiao Guo, Jie Yu
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Patent number: 8522067Abstract: 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: GrantFiled: October 15, 2010Date of Patent: August 27, 2013Assignee: STMicroelectronics, Inc.Inventor: Cecilia Ozdemir
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Patent number: 8184390Abstract: 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: GrantFiled: November 23, 2009Date of Patent: May 22, 2012Assignee: Link—A—Media Devices CorporationInventors: Haitao Xia, Yenyu Hsieh
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Patent number: 8139305Abstract: 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: GrantFiled: September 14, 2009Date of Patent: March 20, 2012Assignee: LSI CorporationInventors: George Mathew, Hongwei Song, Yuan Xing Lee
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Patent number: 7742250Abstract: 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: GrantFiled: January 12, 2007Date of Patent: June 22, 2010Assignee: Seagate Technology LLCInventors: Jeff Nelson, Farhad Navid, Richard Martin, Anton Viktorovich Goldade
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Publication number: 20080266695Abstract: 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: ApplicationFiled: June 27, 2008Publication date: October 30, 2008Applicant: YAMAHA CORPORATIONInventor: Ibuki Handa
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Patent number: 7302749Abstract: 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: GrantFiled: May 10, 2004Date of Patent: December 4, 2007Assignee: Robert Bosch GmbHInventors: Helmut Kreuzer, Eberhard Rau, Reinhard Bezner
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Patent number: 6894855Abstract: 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: GrantFiled: August 27, 2002Date of Patent: May 17, 2005Assignee: Kabushiki Kaisha ToshibaInventors: Yuka Aoyagi, Akihiko Takeo
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Patent number: 6647445Abstract: 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: GrantFiled: April 23, 2002Date of Patent: November 11, 2003Inventor: Eugene Rzyski
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Patent number: 6476743Abstract: 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: GrantFiled: November 9, 2001Date of Patent: November 5, 2002Assignee: Iders IncorporatedInventors: Bradley Dale Brown, Shamir Nizar Mukhi
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Patent number: 6124993Abstract: 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: GrantFiled: May 20, 1994Date of Patent: September 26, 2000Assignee: Ampex CorporationInventor: Kurt F. Hallamasek
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Patent number: 6021281Abstract: 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: GrantFiled: April 22, 1998Date of Patent: February 1, 2000Assignee: Minolta Co., Ltd.Inventors: Yoshiharu Tanaka, Junichi Tanii
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Patent number: 5623376Abstract: 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: GrantFiled: April 26, 1994Date of Patent: April 22, 1997Assignee: Canon Kabushiki KaishaInventors: Shingo Ikeda, Shinichi Yamashita
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Patent number: 5466920Abstract: 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: GrantFiled: November 8, 1991Date of Patent: November 14, 1995Assignee: MicroBilt CorporationInventors: Parameswaran B. Nair, Kumar S. Choudhuri, James T. Stills, John C. Evans
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Patent number: 5453603Abstract: 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: GrantFiled: January 4, 1994Date of Patent: September 26, 1995Assignee: Best Lock CorporationInventors: Roger K. Russell, Mark W. Voth
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Patent number: 5396370Abstract: 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: GrantFiled: October 21, 1993Date of Patent: March 7, 1995Assignee: Siemens Nixdorf Informationssysteme AGInventors: Hubert Behr, Wolfgang Fick, Waldemar Jager
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Patent number: 5305156Abstract: 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: GrantFiled: October 14, 1992Date of Patent: April 19, 1994Assignee: TEAC CorporationInventor: Masao Takei
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Patent number: 5229894Abstract: 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: GrantFiled: December 13, 1991Date of Patent: July 20, 1993Assignee: M.R. Sensors LimitedInventors: Alan J. Collins, Selvaratnam
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Patent number: 5130863Abstract: 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: GrantFiled: March 28, 1989Date of Patent: July 14, 1992Assignee: Canon Kabushiki KaishaInventors: Shinichi Yamashita, Kenichi Nagasawa, Tomohiko Sasatani, Toshihiro Yagisawa
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Patent number: 5128809Abstract: 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: GrantFiled: June 29, 1989Date of Patent: July 7, 1992Assignee: Digital Equipment CorporationInventors: Michael D. Leis, Robert Y. Noguchi, Joseph M. Rinaldis, Robert A. Rubke
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Patent number: 5003408Abstract: 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: GrantFiled: August 4, 1988Date of Patent: March 26, 1991Assignee: Irwin Magnetic Systems, Inc.Inventors: Richard A. Farkas, Marlin K. Klumpp, Michael L. Bolt, Housan Dakroub
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Patent number: 4987500Abstract: 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: GrantFiled: November 14, 1988Date of Patent: January 22, 1991Assignee: Brier Technology, Inc.Inventors: John Bizjak, Michael Hassel, David Niemann
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Patent number: 4876615Abstract: 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: GrantFiled: October 30, 1987Date of Patent: October 24, 1989Assignee: Nakamichi CorporationInventor: Tadaaki Chikashige
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Patent number: 4837782Abstract: 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: GrantFiled: April 14, 1988Date of Patent: June 6, 1989Assignee: NEC CorporationInventor: Eisaku Sasaki
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Patent number: 4821293Abstract: 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: GrantFiled: May 11, 1988Date of Patent: April 11, 1989Assignee: Sony CorporationInventors: Kazutoshi Shimizume, Mutsumi Kimura
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Patent number: 4809304Abstract: 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: GrantFiled: March 17, 1986Date of Patent: February 28, 1989Assignee: Bull, S. A.Inventor: N. Vo Chau
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Patent number: 4809301Abstract: 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: GrantFiled: November 25, 1987Date of Patent: February 28, 1989Assignee: The United States of America as represented by the Secretary of the Air ForceInventor: Melvin H. Rhodes
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Patent number: 4714968Abstract: 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: GrantFiled: March 3, 1986Date of Patent: December 22, 1987Assignee: Honeywell Information Systems ItaliaInventor: Bonifacio Troletti
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Patent number: 4672483Abstract: 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: GrantFiled: July 3, 1985Date of Patent: June 9, 1987Assignee: NEC CorporationInventor: Michitaka Kawada
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Patent number: 4651328Abstract: 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: GrantFiled: November 4, 1985Date of Patent: March 17, 1987Assignee: U.S. Philips CorporationInventors: Cornelis J. den Hollander, Geert Winters
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Patent number: 4628372Abstract: 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: GrantFiled: July 20, 1984Date of Patent: December 9, 1986Assignee: Sony CorporationInventor: Takashi Morisawa
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Patent number: 4553177Abstract: 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: GrantFiled: November 9, 1983Date of Patent: November 12, 1985Assignee: Nixdorf Computer AGInventor: Peter Scholich
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Patent number: 4532559Abstract: 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: GrantFiled: February 14, 1983Date of Patent: July 30, 1985Assignee: Prime Computer, Inc.Inventors: Charles C. Long, David M. Lounsbury, Richard R. Curtin
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Patent number: 4503472Abstract: 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: GrantFiled: September 1, 1983Date of Patent: March 5, 1985Assignee: Burroughs Corp.Inventor: William A. Lacher
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Patent number: 4481549Abstract: 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: GrantFiled: December 22, 1980Date of Patent: November 6, 1984Assignee: Tektronix, Inc.Inventor: John G. Theus
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Patent number: 4473851Abstract: 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: GrantFiled: February 22, 1982Date of Patent: September 25, 1984Assignee: Aisin Seiki Kabushiki KaishaInventors: Nobuyoshi Nagura, Taneichi Kawai