Abstract: A self-scaling differential signal decoder which accepts first and second input signals and provides an output representative of the difference therebetween which output is scaled as if the sum of the input signals were equal to a predetermined value, avoids the problems associated with slow AGC control circuits and with operational sequence control systems commonly used in such devices and is operable at up to video speeds by exploiting the properties of a transistor differential long-tail-pair amplifier where the ratio between its output currents is proportional to the antilogarithm of the difference between its input voltages, the sum of the output currents is equal to the controlled value of the constant current source and the input to the long-tail pair is provided by a differential logarithmic amplifier, the decoder being employed in a tribit servo-track reader.

Abstract: Apparatus for controlling the speed of advancement of a magnetic tape in a video tape recordor (VTR) of the type including a rotary magnetic head assembly for recording and reproducing an information signal with respect to a plurality of record tracks extending obliquely on a magnetic tape, comprises a recording section including a control signal generator which generates a control signal, a pilot signal generator which generates a pilot signal having a predetermined frequency, an AM modulator which amplitude modulates the pilot signal by the control signal to produce a superimposed or amplitude-modulated signal which is recorded in a control track on the magnetic tape by a fixed magnetic head; and a reproducing section including the fixed magnetic head for reproducing the superimposed signal recorded in the control track on the magnetic tape, a limiter circuit for detecting the pilot signal from the reproduced superimposed signal, an FM detector for detecting a frequency fluctuated component of the detected

Abstract: Dynamic skew correction of multichannel analog information is presented. A arrier frequency signal is amplitude modulated by a lower frequency modulation signal derived from a common source and having predetermined zero crossing and phase characteristics. The amplitude modulated carrier signal is recorded on at least two of a plurality of channels simultaneously with recording on the respective channels of the analog information. Upon playback, the various modulated signals are derived from the plurality of channels simultaneously with the playback analog information recorded on the respective channels. The predetermined characteristics of the derived carrier and lower frequency modulation signals are used for processing the played back information for time displacing the information derived from the individual channels for correcting skew errors between the various channels.

Abstract: Recording apparatus which receives a signal, double-sideband amplitude modulates a carrier with at least three times the highest carrier frequency, with the signal, and records the modulated carrier on a recording medium. The reproducing apparatus reproduces the signal modulated carrier substantially free from superimposed noise and delivers it to an external circuit, where it may be recorded or may be demodulated and the signal recorded.

Abstract: A carrier wave at a frequency higher than the frequency of an input signal to be recorded is pulse width modulated with the input signal at the pulse width modulator, and the modulated signal thus obtained is supplied to a vertical magnetization recording head. The vertical magnetization recording head is held in contact with a magnetic tape having a rectangular hysteresis characteristic, and the modulated signal is recorded by vertical magnetization recording on the magnetic tape. The signal recorded by the vertical magnetization recording is reproduced with a reproducing head having a high sensitivity reproducing characteristic with respect to the input signal component of the pulse width modulation signal recorded on the recording medium and a low sensitivity characteristic with respect to the carrier wave component of the modulation signal.

Abstract: A digital magnetic recording system in which information is recorded as transitions between regions magnetized in opposite senses. In the read channel the output of the read head is applied to modulate a carrier, passed through a surface acoustic wave transversal filter and then demodulated, and the resulting transformed waveform is sampled. The surface acoustic wave transversal filter is designed to control the manner in which the transformed versions of elementary read pulses interfere at the sampling instants in such a way as to facilitate recovery of the recorded bits.

Abstract: A system for reproducing and/or transmitting analog audio information is disclosed which provides for the correction of time base errors. An inaudible pilot signal accompanies the audio information. Correction circuitry examines the frequency and phase characteristics of the pilot signal to develop signals for effecting correction of the errors.

Abstract: A magnetic recording and reproducing system is disclosed in which a frequency-modulated input signal is recorded on a magnetic medium together with a further signal which is discriminative from the frequency-modulated signal. The recorded frequency-modulated signal and further signal are frequency-demodulated so that the former reverts to the input signal and the latter represents an FM noise signal which is generated due to the wow and flutter during the recording and/or reproducing process. The extracted noise signal is mixed with the reproduced input signal thereby canceling an FM noise component in this reproduced signal. The mentioned further signal may be an amplitude-modulated signal of or a carrier wave signal for the frequency-modulated input signal.

Abstract: In this controlled decay envelope detector, a capacitor is used to hold the momentary peaks of the input signal. Its only discharge current path is controlled by a circuit which simultaneously monitors the capacitor voltage and the input signal such that the discharge current from the capacitor is proportional to the voltage difference between the capacitor voltage and a conventional exponential RC decay voltage provided in the control circuit. The resulting discharge from the capacitor, in response to a negative-going step input voltage, is an increasing current starting from zero at the time of the transient. The resulting detector output describes an upwardly convexing voltage decay curve which holds its level essentially equal to that of the initial peak input voltage until the next estimated peak input occurs. Only when the next peak input does not come, or is lower than the last one, will the output start dropping at an increasing rate, which provides a correspondingly precise detection of the envelope.

Abstract: A video signal recording and reproducing system in which a video signal to be recorded is passed through preemphasis means and subsequently angular modulated so that it is recorded on a record medium. During playback operation, the video signal is angular demodulated and deemphasized through a deemphasis means. Preemphasis means comprises both a non-linear preemphasis circuit and a fixed preemphasis circuit. The deemphasis means similarly comprises a fixed deemphasis circuit and a non-linear deemphasis circuit. Each of the non-linear circuits is responsive to the amplitude of an input signal thereon.

Abstract: Data, in the form of a sequence of binary bits of frequency F.sub.O, is detected by deriving a clock signal H of frequency F.sub.O in response to the sequence. A level transposing device responsive to the sequence and signal H derives a bi-level signal DEI. An integrating apparatus responds to DEI to derive a signal DEINT. A decision circuit responsive to DEINT determines the polarity of signal DEINT and derives binary data bits having values that are a function of the polarity. The direction and duration of charging current supplied to a pair of capacitors of the integrator are controlled as a function of the polarity and duration of each of the levels of signal DEI, so the capacitors are respectively charged in response to even and odd numbered bits. The integrator is reset to zero at the end of the integrating operation for each level and the capacitive integrating member is supplied with a charging current proportional to F.sub.O.

Abstract: An integrator integrates the central portion of each signaling interval of a PCM input signal for a time less than the reciprocal of the PCM baud rate. Means responsive to the integrated signal or a manifestation thereof performs a comparison operation at the end of the integration period and stores the result until the end of the next following period. The integrator is reset between integration periods when transitions of the signal are likely to occur whereby immunity to PCM signal amplitude variations and transition edge distortion is enhanced and the probability that the integration will be monotonic is enhanced, thereby reducing the detector error rate.

Abstract: A current source supplies current to an integrator representative of a difference between the instantaneous and average values of a video signal having a PCM data component time division multiplexed with an analog luminance component. The integrator is enabled during the central portion of each PCM signaling interval and reset to a reference level during initial and terminal portions of the intervals. Asymmetry of the peak-to-peak PCM signal levels with respect to the average signal level tends to result in asymmetrical excursions of the integrator output voltage relative to the reference level. This asymmetry is corrected by means of a charge source that supplied a predetermined quantity of charge continuously or in discrete packets to the integrator during the central portion of each PCM signaling interval.

Abstract: A method of demodulating a pulse width modulation encoded analog signal wherein the analog signal is retrieved from individual pulse width modulation cycles. A method of sampling and outputing the retrieved analog signal only if missing pulse detectors confirm that the pulse width modulation cycle was valid. And a method generating a second but inverted play-back signal permitting use of two identical pulse width modulation transition descriminators-detectors.

Abstract: An economical, practical method of bringing the major portion of a classroom teaching experience to a remote student. The teacher's oral and blackboard presentations are recorded, forwarded to the student and played back on equipment that reproduces the teacher's voice and his or her graphics that would normally be presented on a blackboard, retaining the time correlation between the spoken and written texts.

Abstract: In recording periodic information signals having first intervals and second intervals which are subdivisions of the first intervals, for example, the chrominance components of color video signals having field and line intervals, and which are recorded in respective areas or increments of successive parallel tracks on a record medium; interference due to crosstalk between signals recorded in next adjacent tracks is substantially reduced or eliminated by recording the information signals in such next adjacent tracks with first and second carriers, respectively, which have their phases changed in opposite directions by 2.pi./N and 2.pi./M, respectively, for successive second intervals, with each of N and M being a whole number greater than 2 which is negative to indicate a phase change or shift in the clockwise direction or positive to indicate a phase change in the counterclockwise direction, and with each of N and M being selected to satisfy the equation 1/N-1/M=1/2.

Abstract: A system for recording and later reproducing video signals on a magnetic recording medium by producing a modulated signal in which the video information is carried primarily on only one sideband and the carrier, which may be suppressed by certain types of modulation is at a frequency within the band occupied by the video signals prior to modulation. The carrier may originally be at a higher frequency and be converted to the aforementioned frequency, which is also within a frequency band that includes the peak reproduction point in the response characteristic of a magnetic recording and reproducing system. In the case of certain types of modulation the carrier is phase-and frequency-controlled to eliminate interference between signals recorded on adjacent tracks on the magnetic medium.

Abstract: Clock and binary NRZ signals are derived from a data track of a magnetic tape. The data track includes a pattern having a substantially constant wave length of magnetic flux variations along its length. The variations are in the form of a carrier wave having only three predetermined envelope levels. One of the levels is provided for clock pulses and the other two levels are provided for the magnitudes of the binary NRZ signals. A replica of the variations is transduced by a head into an electrical signal. First and second signals are derived in response to the electric signal to respectively indicate the carrier wave having amplitudes above first and second values of the levels. The first level is greater than the level of one of the binary signals, while the second level is greater than the first level and the level of the clock pulses.

Abstract: Unauthorized duplication of recorded program material upon magnetic tape, commonly known as tape piracy, is rendered detectable by the present method and apparatus for preparing the program material. The method and apparatus prepare recorded audible program material by eliminating narrow low and high frequency bands of signals from the program material, inserting a preselected low frequency signal in the low frequency band, modulating a predetermined high frequency signal with the low frequency signal, and inserting the modulated high frequency signal in the high frequency band. Subsequent copying of the recorded program material having these inserted signals will introduce a phase shift between the low and high frequency inserted signals.Such a phase shift is detected by a method and apparatus which recover the signal recorded upon the magnetic tape recording suspected to be a duplicate, and filter the recovered signal to detect signals within the high and low frequency bands.

Abstract: An economical system for both recording multiplexed digital data on a tape recorder and decoding the stored data.

Abstract: A method and apparatus is disclosed for reducing crossover modulation distortion generated at a sub-channel and for minimizing phase differences between 4-channel signals that are recorded on a recording medium in a multiple-frequency manner. More specifically, the present invention is directed to reducing or eliminating the beat distortion that is caused by crosstalk between a sub-channel signal and a main channel signal when the main channel signal is recorded according to RIAA-TYPE recording characteristics.

Abstract: A video tape recorder wherein the video signal is recorded on the tape as a frequency-modulated signal. The video recorder comprises a transport for the tape which is constructed suitably for reversing the direction of tape movement during signal recording and reproducing. The video signals are successively transduced on or from longitudinally extending parallel tracks on the tape. Initiating of the reverse movement of tape is improved by the use of a special high frequency signal. Said frequency also could be higher than the upper frequencies which can still be transduced by the used magnetic head at playback. Easily manufactured circuits are provided for the highly accurate detection of the special high frequency signal. Said frequency should be in a higher frequency range than the highest frequency of the video signals, more exactly above the white level of the video signals.