Multi-frequency Patents (Class 360/43)
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Patent number: 4470081Abstract: The Controlled Return to A.C. (CRA) magnetic recording and reproducing system applies a high frequency erase signal continuously to the write head except at the detents. At the detents polarity controlled interruptions of the high frequency erase signal are embedded therein. A positive interruption, a negative interruption and the absence of an interruption provides a ternary recording capability at the detent. The high frequency erase signal is controlled in phase to provide polarity coherent interruptions. A CRA cell includes two controlled interruptions providing a mapping of three binary digits into two CRA digits. The controlled interruption results in an opposite polarity pulse pair upon readback.Type: GrantFiled: January 15, 1982Date of Patent: September 4, 1984Assignee: Sperry CorporationInventor: Chao S. Chi
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Patent number: 4462051Abstract: To decode a binary signal without regard to the speed at which it is read, each transition in the binary signal is detected, and the time lapse between successive transitions is determined to thereby establish the length of a pulse in the binary signal. The length of one pulse is compared with that of the immediately preceding bit cell to determine whether their lengths are approximately the same or vary by a factor of approximately 2. If the two compared lengths are approximately the same, it is recognized that there is no change in the information conveyed by the signal and therefore the binary state of the most recently detected pulse is representative of the previously established binary state of the signal. However, if the pulse has a duration of approximately one half that of the preceding bit cell, a change in the state of the binary information being conveyed is recognized, and an appropriate indication is provided to signal such change.Type: GrantFiled: April 2, 1982Date of Patent: July 24, 1984Assignee: Ampex CorporationInventor: Steven S. Chan
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Patent number: 4459623Abstract: An all digital method and apparatus for recovering NRZ information from MFM data wherein the MFM pulse stream is monitored through hypothetical windows, the receipt of a pulse during a particular window providing information about the data state(s) represented by the pulse and tracking adjustments required to recover subsequent pulses, and further wherein each window is divided into a large number of subinterval's so that the coincidence of a pulse with a particular subinterval provides information about the amount and direction by which the position of subsequent windows should be changed for tracking correction; the windows and subintervals being implemented by the execution of one of a number of step sequences, the particular step sequence being executed indicating the classification of a pulse received during the particular step sequence, and the step being executed at the time of receipt of the pulse indicating required tracking adjustments.Type: GrantFiled: January 18, 1982Date of Patent: July 10, 1984Assignee: MDS Qantel CorporationInventors: Fletcher M. Glenn, II, James A. Fosse
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Patent number: 4453157Abstract: A bi-phase space code data signal reproducing circuit comprises a clock pulse supplying circuit for supplying a clock pulse having a period which is 1/N (N is an integer) of a bit period T of a bi-phase space code data signal to be reproduced, a shift register supplied with the clock pulse, for performing a shifting operation, a main flip-flop supplied with the data signal and an output signal obtained from an intermediate part of the shift register, for holding a sampling value of the data signal at a point which is substantially T/4 from the beginning of each data of the data signal, an exclusive-OR circuit supplied with an output signal of the main flip-flop and said data signal, and a reproduced data obtaining circuit for sampling an output signal of the exclusive-OR circuit by a sampling clock at a point which is substantially 3T/4 from the beginning of each data of the data signal obtained from the shift register, to obtain a reproduced data.Type: GrantFiled: January 21, 1982Date of Patent: June 5, 1984Assignee: Victor Company of Japan, Ltd.Inventor: Kenji Kaneko
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Patent number: 4441193Abstract: An electronic circuit produces a composite signal in which a low frequency component signal is followed by a high frequency component signal such that the composite signal resists transmission line distortion. To that end, the circuit generates the half-cycle of the high frequency component signal that immediately follows the low frequency component signal with a time duration that is longer than one-half the period of the high frequency by a predetermined amount of time; and then it generates the next half-cycle of the high frequency component signal with a time duration that is less than one-half the period of the high frequency by a like amount of time.Type: GrantFiled: May 3, 1982Date of Patent: April 3, 1984Assignee: Burroughs CorporationInventor: John L. Bell
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Patent number: 4426667Abstract: A pulse width modulation system for encoding and decoding digital information in which the encoded signal comprises a series of transitions among different signal levels wherein the length of time between transitions determines the value of a digit, so that each digit is represented by one and only one transition.Type: GrantFiled: May 17, 1978Date of Patent: January 17, 1984Assignee: Savin CorporationInventors: Dale P. Masher, Leonard J. Chaitin
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Patent number: 4383281Abstract: The invention relates to the generation of a digital magnetic recording signal modulated in phase in correspondence with the transitions of the corresponding data signal. According to the invention, the D.C. component of the recording signal is suppressed so that the recording winding can be excited by this signal by means of a transformer. The recording head can include only a single turn.Type: GrantFiled: June 24, 1980Date of Patent: May 10, 1983Assignee: Compagnie Internationale pour l'Informatique CII-Honeywell Bull (Societe Anonyme)Inventor: Jean-Paul Lesieur
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Patent number: 4376958Abstract: There is described methods and circuitry for decoding modified frequency modulated (MFM) information signals as obtained from rotating magnetic storage devices, such as floppy disks and hard disks used in computers. The novel technique involves twice squaring an information carrying data signal mathematically and without saturation, deriving a clock signal from the twice squared data signal using a phase lock loop and thereafter recovering an information signal from said data signal and clock signal.Type: GrantFiled: July 8, 1980Date of Patent: March 15, 1983Assignee: Elcomatic LimitedInventor: Archibald M. Pettigrew
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Patent number: 4370747Abstract: A circuit arrangement for transmitting binary data elements `0` and `1` by frequency shift using two tone frequencies f0 and f1. The circuit arrangement comprises a modulator, an exclusive OR-gate and an integrator. A data signal DS produces from the modulator a digital signal DSS which by decoding of the integrator results in a tone signal TS comprising f0 or f1. The action of the OR-gate to which both signals DS and DSS are applied causes the amplitude of the tone signal TS to be substantially the same for each of the tone frequencies f0 and f1. The OR-gate may change either the effective resistive input into the integrator for each tone frequency or it may change the amplitude of the signal DSS for each tone frequency.Type: GrantFiled: December 15, 1980Date of Patent: January 25, 1983Assignee: U.S. Philips CorporationInventors: Richard E. F. Bugg, Derek J. Parkyn
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Patent number: 4367496Abstract: The invention relates to a method and circuit arrangement for magnetic recording of a digital data signal composed of a set of transitions. A recording signal is formed by superposition on the data signal of a high frequency, constant amplitude, magnetic biasing signal S.sub.p. The biasing signal is phase-modulated relative to the data signal transitions. The invention remedies "peak shift" and can be applied to any rectangular or sinusoidal biasing signal.Type: GrantFiled: June 4, 1980Date of Patent: January 4, 1983Assignee: Compagnie Internationale pour l'Informatique CII-Honeywell Bull (Societe Anonyme)Inventor: Jean-Paul Lesieur
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Patent number: 4327383Abstract: A read circuit for a floppy disk drive is disclosed. The circuit comprises a read head for generating an electrical signal corresponding to recorded data, plus an amplifier, equalizing filter, low pass filter and decoder for processing the electrical signal.Type: GrantFiled: September 26, 1980Date of Patent: April 27, 1982Assignee: Siemens CorporationInventor: Dewilton R. Holt
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Patent number: 4319287Abstract: An address mark code for use with Modified Frequency Modulation encoding wherein (1) the first bit of the 8 bit address mark byte is always zero, (2) the address mark byte eliminates a clock pulse between the second and third zero of a string of at least four zeros, (3) the address mark byte contains the binary pattern 101, and (4) the spacing between data pulses and/or clock pulses of the address mark byte is between 1T and 2T where T is the width of a data cell of the address mark.Type: GrantFiled: May 24, 1978Date of Patent: March 9, 1982Assignee: Xerox CorporationInventor: Robert L. Swenson
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Patent number: 4308561Abstract: A reproducing circuit is provided for reproducing digital information recorded in a cassette tape by frequency modulation in which different first and second digital logic levels are respectively represented by first and second repeated signals having respective first and second repeated frequencies, the first repeated frequency being higher than the second. A pulse forming circuit produces first and second pulse signals having the first and second repeated frequencies in response to the signals recorded on the cassette tape. The first or second pulse signals are applied to a one-shot circuit as a trigger signal and to the control input terminal of a flip-flop circuit as a control signal. The output of the one-shot circuit is supplied to the data input terminal of the flip-flop circuit, whereby reproduced digital information corresponding to the digital information recorded on the cassette tape is derived from the output terminal of the flip-flop circuit.Type: GrantFiled: May 14, 1980Date of Patent: December 29, 1981Assignee: Hitachi, Ltd.Inventors: Toru Onodera, Akira Ohsawa, Hideki Nishino, Masao Watari
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Patent number: 4287596Abstract: A data recovery circuit for use in a data processing system where plural subsystems are linked by a bit serial transmission line. The data transmitted over the bit serial transmission line is in the form of a phase encoded (PE) pulse signal. The data recovery circuit includes a time delay circuit for delaying the PE pulse signal by a three-quarter bit period. The three-quarter bit period delay signal permits the generation of a control clock signal. The control clock signal is used in sampling the PE pulse signal at three-quarter bit period points in order to generate a control signal that indicates the absence or presence of a transition at the midpoint of each bit period of the PE pulse signal. The control signal is used to generate a recovered clock signal by logically combining the control signal with the PE pulse signal and a one-half bit period delayed PE pulse signal.Type: GrantFiled: November 26, 1979Date of Patent: September 1, 1981Assignee: NCR CorporationInventor: Venu Chari
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Patent number: 4267595Abstract: A decoder is provided which does not require the use of a retiming circuit. The decoder operates with an AMI signal, and operates to detect a transition occurring at the center of a bit cell to blank out those transitions which do not coincide with the encoding clock. The decision is made by examining the time between received transitions. Once this is accomplished, an asynchronous logic circuit with two states of memory can be used to structure the decoded AMI data into a NRZ or other format by storing the transitions which occur in the middle of the previous bit cell and outputting a first binary value during the following bit cell for a transition, or if no transitions have occurred in the middle of the previous bit cell, a second binary value is outputted during the following bit period.Type: GrantFiled: February 4, 1980Date of Patent: May 12, 1981Assignee: International Telephone and Telegraph CorporationInventor: Victor M. Hernandez
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Patent number: 4260952Abstract: Incoming diphase signals E which have base bit intervals delineated by spaced clocking signals with data information occurring between the clocking signals are fed to a four bit shift register 10 which in cooperation with an exclusive OR-gate 14 generates a pulse D for each diphase signal E transition. Upon receipt of a preamble comprising four diphase signal transitions, a shift register 16 provides a signal MSR which initiates the decoding of the following data information. A counter 24 stores counts related to the time intervals between each two successive clocking signals and counters 26 and 28 store a count related to an immediately subsequent time period which is three-fourths of the time interval. The occurrence of data information is sensed by a logic array 20 during successive time periods and a non-return to zero mark-space output signal K is stored in a flip-flop 22. The logic array 20 continually updates the counts stored by the counters 24, 26-28.Type: GrantFiled: July 17, 1979Date of Patent: April 7, 1981Assignee: Teletype CorporationInventor: James W. Thomas, Jr.
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Patent number: 4245263Abstract: Information to be written in the form of magnetic flux reversals on the surface of a disk or diskette is applied in serial fashion to a first shift registor. The parallel outputs of the shift register address a PROM. The PROM output is applied to a second shift register in the form of clock and data bits to be written on the disk or diskette magnetic surface. Control signals applied to the PROM address terminals select the mode, FM or MFM, the address mark or if precompensation is required.Type: GrantFiled: May 14, 1979Date of Patent: January 13, 1981Assignee: Honeywell Information Systems Inc.Inventors: Donald J. Rathbun, Peter P. Campbell
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Patent number: 4232216Abstract: A device for reading an item of information defined by a plurality of different intervals between consecutive elements on a data carrier, and corresponding methods of recognizing an item of information defined by a plurality of different intervals between consecutive pulses of a first pulsed signal. The device includes first and second element detectors arranged for motion relative to the elements on the data carrier, which detectors generate responses to the elements. The element detectors are spaced from each other by a distance e such that the responses to each element generated by said second element detector have a time delay e corresponding to the physical distance e with respect to the responses generated by said first element detector. The device further includes means for comparing the response of said first and second element detectors to produce an output signal representing the item of information.Type: GrantFiled: December 12, 1978Date of Patent: November 4, 1980Assignee: Compagnie Internationale pour l'Informatique CII-Honeywell Bull (Societe Anonyme)Inventor: Michel Helle
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Patent number: 4227184Abstract: A method of balancing digital signals encoded in the Miller Code, which is inherently an unbalanced code. Additional coding rules are utilized based on the use of a transition interval extending from the begining of a bit period to the begining of the next but one bit to define an adjacent pair of Binary I's for certain specific data sequences.Type: GrantFiled: December 19, 1978Date of Patent: October 7, 1980Assignee: International Standard Electric CorporationInventors: George A. Howells, Douglas E. Woodman
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Patent number: 4219851Abstract: This relates to a digital data recovery system for decoding group coded data bits stored on magnetic tape whereon a "1" is represented by a flux reversal and an "0" is represented by the absence of a flux reversal with no more than two successive zeros throughout the data record. Input logic detects transitions of input data and forwards this information to an envelope detector which determines if subsequent transitions represent valid data. The presence of valid data enables a data rate detector which determines the average data rate. An output sequencer determines when a decoded output data bit should be generated and its proper polarity.Type: GrantFiled: November 24, 1978Date of Patent: August 26, 1980Assignee: Honeywell Information Systems Inc.Inventor: Nicholas S. Lemak
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Patent number: 4185273Abstract: An automatic means for decoding a wide data range of Manchester code data. Variable delay means are provided for the Manchester code decoder which are digitally controlled in response to the output of a data rate sensing circuit that provides a digital equivalent of the sensed data rate. The digital equivalent of the sensed data rate is used to optimize the amount of delay in the Manchester code decoder for the particular data rate of the data being received.Type: GrantFiled: July 27, 1977Date of Patent: January 22, 1980Assignee: The United States of America as represented by the Secretary of the NavyInventor: Richard L. Gowan
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Patent number: 4184179Abstract: A system for reproducing a recorded binary signal from a recording medium that may be read at varying speeds is disclosed. The recording medium in a magnetic recording medium in which the binary signal was recorded by effecting predetermined alternating flux changes in the recording medium, and in which the distance of separation between consecutively effected predetermined flux changes does not exceed a first predetermined distance and is not less than a second predetermined distance.Type: GrantFiled: February 24, 1978Date of Patent: January 15, 1980Assignee: Cubic Western DataInventor: Chandler R. Deming
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Patent number: 4183066Abstract: A method and apparatus for recording data on a rotating magnetic disk at plural density rates on different areas of the disk is disclosed. The method is particularly useful in magnetic disk recording systems in which the header or control fields of the recorded information are recorded in "single" density FM recording and the data fields of the recorded information are in "double" density modified frequency modulation (MFM) code. The technique involves changing the conventional MFM coding rules to prevent certain data patterns from appearing to the data recording system read circuitry as part of the control fields. In particular, the data pattern 011110 is encoded according to the invention as a data pattern which consists of 000000 with synchronization bits between the first and second, third and fourth, and fifth and sixth data bits. This encoding modification prevents any misinterpretation of the data field as part of a control field.Type: GrantFiled: July 17, 1978Date of Patent: January 8, 1980Assignee: Digital Equipment CorporationInventor: Albert L. Anderson
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Patent number: 4180837Abstract: The invention relates to a magnetic coding method. It is characterized by e superposing of a first binary message at a given frequency and a binary message at double frequency in space phase. Application to credit cards with a magnetic track.Type: GrantFiled: March 22, 1978Date of Patent: December 25, 1979Assignee: Transac - Compagnie pour le Developpement des Transactions AutomatiquesInventor: Andre Michaud
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Patent number: 4167760Abstract: The apparatus and method of this invention provides an improved decoder capable of decoding data that has been encoded in accordance with the Bi-phase or Manchester encoding rules, which encoded data may be transmitted over a data channel at varying and various rates. A phase-locked loop circuit, including a phase locked oscillator, phase comparator and missing signal level transition detector, forms an integral part of the decoder apparatus that functions to sample the incoming data at the proper time regardless of the rate of data transmission, and decode the data from the encoded data. Also, a clock signal indicative of the data transmission rate is decoded from the encoded data.Type: GrantFiled: March 28, 1978Date of Patent: September 11, 1979Assignee: Ampex CorporationInventor: David G. Decker
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Patent number: 4152731Abstract: An improved read circuit for use with a magnetic read transducer in a magnetic recording system in which the read transducer generates an alternating current playback signal having alternating positive and negative peaks. The read circuit comprises an active differentiator responsive to the playback signal for producing a differentiated signal having positive and negative values with zero crossings in time coincidence with the positive and negative peaks of the playback signal, and a differential comparator for generating an intermediate playback signal having a first value when the differentiated signal is positive and having a second value when the differentiated signal is negative and for generating the complement of the intermediate signal.Type: GrantFiled: December 20, 1977Date of Patent: May 1, 1979Assignee: Motorola, Inc.Inventor: Paul M. Henry
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Patent number: 4151565Abstract: A circuit for the decoding during reading of data prerecorded on a magnetic medium comprising a circuit for recognition of the recording code of the data recorded on the support by the recognition of the frequency of an input signal generated during the reading of the support and a frequency generating circuit controlled by the recognition circuit for generating a signal of predetermined frequency for the conversion of the recording code recognized into a binary code. A read-only memory comprising two zones is responsive to the recognition means for generating correcting words applied to a counter for controlling the position of a decoding window generated by a phase locked loop oscillator.Type: GrantFiled: May 6, 1977Date of Patent: April 24, 1979Assignee: Ing. C. Olivetti & C., S.p.A.Inventor: Mario Mazzola
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Patent number: 4139870Abstract: In a video tape recorder having a tape on which are recorded "0" and "1" binary coded bits of a pulse width modulated signal as for identifying frames of a video signal also recorded on the tape, the tape being advanced past a head detecting the pulse width modulated signal at speeds variable with the fast forward, normal and slow motion mode of operation of the recorder so as to change the bit frequency of the pulse width modulated signal in correspondence with the speed of the tape, a circuit which demodulates the "0" and "1" bits of the detected pulse width modulated signal by comparing the coded pulse width of each succeeding bit (B.sub.i +1) with the width of the preceeding bit (B.sub.i) to make the demodulation substantially independent of the bit frequency and the corresponding speed of the tape so that the circuit operates in each mode of recorder operation. In the preferred embodiment of the circuit, each bit is quantized into periodic pulses which correspond in number to the width of the bit.Type: GrantFiled: March 15, 1977Date of Patent: February 13, 1979Assignee: Sony CorporationInventor: Katsuichi Tachi
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Patent number: 4096378Abstract: An improved method and apparatus are disclosed for the reading (or sensing) and decoding of two frequency "bar coded" or transition coded sensible data. The data may take the form of indicia recorded on various media or it may be transmitted on a communications channel. The method and apparatus include means for simultaneously or separately accommodating both variable velocity scan (or distorted reception) conditions and non-uniform bar widths in the coded data or other variations in the spacing of transition signals in the recorded indicia. Frequency variations in transmitted data signals can also be accommodated. Hand held sensor or "wand" scanning of coded tangible indicia-bearing media is facilitated for either optically or magnetically recorded data indicia. Correct interpretion of frequency-distorted transmitted data is also made possible.Type: GrantFiled: February 5, 1976Date of Patent: June 20, 1978Assignee: International Business Machines CorporationInventor: Albert Watson Vinal
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Patent number: 4088879Abstract: An amplifying device operative to sense changes in the speed of an encoded card as it is being read so as to be able to adjust the reading rate to compensateably follow said changes. The amplifying device is also able to differentially peak sense pulses read thereby disallowing noise transients.Type: GrantFiled: August 4, 1975Date of Patent: May 9, 1978Assignee: Burroughs CorporationInventors: Eugene F. Banka, Roger F. Thompson
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Patent number: 4087840Abstract: Disclosed are a method and an apparatus for magnetically recording and reproducing physiological information such as in an electrocardiogram. The ECG signal is pulse width modulated (PWM), and the transition points, or zero crossings are stored on magnetic tape. The original PWM signal is then reproduced from the output of the playback head by reacting to the simultaneous occurrence of zero crossings and large magnitude derivative signals. Also disclosed is the concept of automatically reacting to recorded audible information during the reconstruction of the original PWM signal.Type: GrantFiled: June 16, 1976Date of Patent: May 2, 1978Assignee: Carnegie-Mellon UniversityInventors: Ronald J. Zdrojkowski, Richard L. Longini
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Patent number: 4040100Abstract: The picture frames recorded on video magnetic tape are identified by serial binary numbers magnetically recorded along an edge of the tape. The sequential ONE and ZERO bits that form each number occur during equal successive intervals when the tape is transported at constant speed and these bits are detected as electrical pulse excursions, one pulse excursion during the interval for a ONE and no excursions during an interval for a ZERO. The pulses are detected even while the tape is not transported at constant speed as when it is accelerating or decelerating and so, the intervals for the successive binary bits may change rapidly and when that occurs, it is difficult to determine whether the successive excursions define a binary ZERO interval or the first half of a binary ONE interval and so, it cannot be determined whether they represent a binary ONE or a binary ZERO.Type: GrantFiled: September 25, 1975Date of Patent: August 2, 1977Assignee: Adams-Smith IncorporatedInventor: Steven S. Chan
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Patent number: 4012786Abstract: A data decoder is provided which is useful for decoding data magnetically encoded on a magnetic stripe on the back side of a credit card which may be manually moved through a reader at a variable velocity. The data is decoded by comparing the occurrence of voltage pulses after the onset of a bit interval, representing binary data encoded as magnetic flux changes, with a preselected portion of the measured time duration of the preceding bit interval. If a voltage pulse occurs after the onset but before the end of the preselected portion, the data is determined as a binary "one"; if a voltage pulse occurs after the end of the preselected portion, the data state is determined as a binary "zero".Type: GrantFiled: February 5, 1976Date of Patent: March 15, 1977Assignee: TRW Inc.Inventors: Kenneth Thomas McKie, Istvan Steve Olah
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Patent number: 4012785Abstract: A playback circuit for use with a magnetic recording transducer, in a magnetic recording apparatus, the transducer developing an alternating current readback signal having alternating positive and negative peaks, the playback circuit comprising a differentiator responsive to the readback signal and operative to produce a differentiated signal having first and second polarities and having zero crossings in time coincidence with the positive and negative peaks, a bidirectional one-shot device responsive to the differentiated signal and operative to produce a first bistate signal having transitions in time coincidence with the zero crossings and to produce a second signal comprising a sequence of pulses having leading edges that correspond in time to the zero crossings and having trailing edges that lag the leading edges by a predetermined time interval, a latch for producing a third signal having transitions that correspond in time to the trailing edges and having a level that corresponds to the level of the fiType: GrantFiled: February 13, 1976Date of Patent: March 15, 1977Assignee: Shugart Associates, Inc.Inventor: David L. MacDougall, Jr.
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Patent number: 3953888Abstract: A device for reading a binary coded magnetic recording. The device includes a reading head producing a reading signal, a digitizer, and a mechanism for modulating the reading signal to substantially reduce distortion caused by the physical characteristics of the reading head and magnetic recording.Type: GrantFiled: September 18, 1974Date of Patent: April 27, 1976Assignee: Compagnie Honeywell Bull (Societe Anonyme)Inventors: Jacques Droux, Michel Audebert, Gerard Millair
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Patent number: 3949193Abstract: A credit card reader is described which includes two magnetic readout heads whose gaps are spaced from each other a distance equal to one half the distance between adjacent, uniformly spaced bits of binary coded information. The coded data is recorded on a linear length of the credit card. The two similar sets of signals are extracted, one delayed relative to the other, as the heads scan the data. Decoding circuitry is described which provides information corresponding to the recorded data independently of the relative speed at which the credit card is moved or is swept past the readout heads.Type: GrantFiled: January 7, 1974Date of Patent: April 6, 1976Assignee: Electrospace CorporationInventor: Edward F. Dowdell
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Patent number: 3947662Abstract: An improved method and apparatus are disclosed for the reading (or sensing) and decoding of two frequency "bar coded" or transition coded sensible data. The data may take the form of indicia recorded on various media or it may be transmitted on a communications channel. The method and apparatus include means for simultaneously or separately accommodating both variable velocity scan (or distorted reception) conditions and non-uniform bar widths in the coded data or other variations in the spacing of transition signals in the recorded indicia. Frequency variations in transmitted data signals can also be accommodated. Hand held sensor or "wand" scanning of coded tangible indicia-bearing media is facilitated for either optically or magnetically recorded data indicia. Correct interpretation of frequency-distorted transmitted data is also made possible.Type: GrantFiled: December 31, 1974Date of Patent: March 30, 1976Assignee: International Business Machines CorporationInventor: Albert Watson Vinal