Abstract: Digitally designed vertical synchronizing separator and framing circuit in association with a digital servo LSI for a video tape recorder are particularly designed to be noise-free system for a composite synchronizing signal reproduced from the video tape recorder and utilize a reference clock pulse with the synchronizing signal and a counter with a feed back of the contents of the counter to control the supply of said composite synchronizing signal.

Abstract: A video signal is recorded with the associated audio signal inserted as a PCM digital signal in the back porch portions of the horizontal blanking intervals. In order to prevent the video pre-emphasis that is used in high-density recording from degrading the PCM digital signal, the video signal and the PCM digital signal are provided with separate and independent degrees of pre-emphasis. Upon playback, the video signal and the PCM digital signal are provided with corresponding independent respective amounts for de-emphasis. In order to fit a sufficient number of bits into the blanking intervals to provide high quality audio, the back porch portion is first extended by replacing the standard horizontal synch pulses with narrow pulses, so that the following back porch portions are correspondingly elongated.

Abstract: A phase servo circuit for controlling a rotatable magnetic head which is used for recording and/or reproducing a television signal includes a pulse generator for producing a pulse signal synchronous with the rotating phase of the rotatable magnetic head, a phase difference detecting circuit for generating a control signal which is used for controlling the rotating phase of the rotatable magnetic head, the control signal having a pulse width modulated in response to the phase difference between the pulse signal and the vertical synchronizing signal of a television signal to be recorded, another circuit for detecting the phase difference between the aforementioned vertical synchronizing signal and a second vertical synchronizing signal of a reproduced television signal and a modulating circuit for modulating the pulse width of the control signal in response to the output of the phase difference detecting circuit, whereby the phase angle of the first-mentioned and second vertical synchronizing signals are in syn

Abstract: In a digital servo control system, the duty cycle of a pulse width modulated signal for controlling a drive motor is determined by digital numbers representing phase and/or speed errors preset into a memory and circulating counter. The circulating counter is driven by a clock signal which performs a number of cycles during each basic timing interval. A pulse width modulated signal is initiated by a timing pulse and is terminated by each return to zero of the most significant digit of the circulating counter. The time at which the most significant digit of the circulating counter returns to zero at the end of each of its cycles is determined by the number initially preset into it. The memory is gated with the output of a four-bit counter, which increments at the same rate that the circulating counter cycles, to either lengthen each pulse width modulated signal by one clock cycle or not.

Abstract: A digital servo control system for controlling a drive motor accumulates speed and phase error numbers and produces a pulse width modulated signal in response thereto. Phase errors are measured by counting pulses of a clock signal between the arrival of a position signal related to a rotational position of the drive motor and the arrival of a reference signal. An automatic residual error compensating circuit controls a delay applied to the position signal in accordance with residual phase error to minimize the same.

Abstract: The duty cycle of a pulse width modulated signal for controlling a drive motor is determined by the content or numbers stored in a counter and representing phase and/or speed errors. The counter is driven by a clock signal which has a number of cycles during each cycle of the pulse width modulated control signal which is exactly equal to the capacity of the counter. The pulse width modulated signal is initiated by a timing pulse and is terminated by the return to zero of the most significant digit of the counter. The time at which the most significant digit of the counter returns to zero in each cycle is determined by a number initially contained in the counter. The content of the counter is periodically determined according to detected speed and phase errors to update the duty cycle of the pulse width modulated control signal.

Abstract: An automatic tracking servo control system which is adapted to control the tracking of at least one rotary signal reproducing transducer which scans successive parallel record tracks on a movable record medium. Position pulses are generated when the transducer rotates into predetermined position with respect to the record medium, and these position pulses are used in conjunction with control signals which are reproduced from the record medium and which had been recorded at spaced locations therealong in predetermined relation to the record tracks for controlling the position of the transducer with respect to the tracks scanned thereby. A detector detects the relative strength of the signal reproduced by the transducer during periodic intervals.

Abstract: An automatic tracking servo control system which is adapted to control the tracking of at least one rotary signal reproducing head which scans successive parallel record tracks on a movable record medium. Position pulses are generated when the at least one head rotates into predetermined position with respect to the record medium, and these position pulses are used in conjunction with control signals which are reproduced from the record medium and which had been recorded at spaced locations therealong in predetermined relation to the record tracks for controlling the position of the at least one head with respect to the tracks scanned thereby. A detector detects the relative strength of the signal reproduced by the at least one head during periodic intervals. A phase shift circuit shifts the phase of each reproduced control signal as a function of the difference between the relative signal strengths in successive periodic intervals.