Victor Company of Japan, Limited

Masatsugu Kitamura

Hideo Onoye

Masami Yamazaki

Hiroshi Yoshida

Naoki Yamashita

Tsuyoshi Ono

Tokumi Watanabe

Kikuji Wagatsuma

Mitsuaki Tanaka

Yukihiro Kishima

Yutaka Morita

Fumiaki Ohno

Hiroyuki Takekura

Yoshiaki Tanaka

Harukuni Kobari

Mamoru Inami

Zenju Otsuki

Hiroki Shimizu

In an apparatus for generating an aperiodic waveform having a gradually decaying envelope, a sequence of digital samples representing the magnitude of the waveform at sample points is stored in a memory. The stored digital samples are grouped into at least first and second continuous portions, the second portion including that portion of the sequence in which none of the digital samples has a magnitude exceeding 1/n the magnitude of the largest of the digital samples, where n is an integer greater than unity, each of the digital samples of the second portion being scaled by a factor of n. The memory further stores a code indicating the beginning of the second portion. An address counter develops an address signal for sequentially addressing the stored digital samples and code from the memory in response to clock pulses. When the stored code is addressed, an additional clock pulse is supplied from a code detector to the address counter. Each of the addressed digital samples of the first and second portions is scaled and converted to a signal having a magnitude corresponding to the magnitude of the associated digital sample of the sequence.

Aperiodic waveform generation using stored markers identifying scaled

An electronic musical instrument includes a memory in which digital samples of an aperiodic waveform are stored. Digital samples stored in a first portion of the memory represent a rapidly rising portion of the waveform and those stored in a second portion of the memory represent a rapidly declining portion of the waveform whose amplitude and spectral energy distributions are equalized. The first memory portion is addressed in forward scan and subsequently the second memory portion is addressed recyclically in forward and rearward scans to generate an output waveform having a first part corresponding to the rising waveform section and a second part corresponding to a series of the recyclically addressed versions of the equalized waveform section. After delivery of the first part of the output waveform, a monotonically declining envelope is impressed upon the amplitudes and the spectral energy distributions of the second part.

Periodic wave form generation by recyclically reading amplitude and

In a data compression system, a digital signal comprising a series of digital samples and a sampling datum indicating the sampling interval of the digital samples are written into a read-write memory (M2). The digital samples and the associated sampling datum are read out of the memory into first and second digital-to-analog converters (DAC1, DAC2), respectively. The output of the first digital-to-analog converter is applied to a variable frequency low-pass filter (5) to remove the components having frequencies higher than a presettable frequency limit value which is variable as a function of the output of the second digital-to-analog converter so that the cut-off frequency is lower than one-half the sampling frequency to eliminate quantum noise.

Method and system for decoding a digital signal using a variable

An electronic musical instrument includes a first memory in which audio samples of lower frequency components of an aperiodic waveform are stored and a second memory in which audio samples of a higher frequency components of the waveform are stored. Digital samples stored in a first portion of the second memory represent a rapidly rising portion of the higher frequency waveform and those stored in a second portion of the memory represent a rapidly declining portion of the higher frequency waveform whose amplitude and spectral energy distribution profiles are preferably equalized. The first memory is addressed throughout in forward scan to generate a first output waveform. The second memory is addressed in an initial forward scan throughout its first and second portions and the direction of scan is reversed at the end of the second portion to recyclically address it in rearward and forward directions to generate a second output waveform, which is combined with the first output waveform. A monotonically declining envelope is preferably impressed upon the second output waveform to reconstruct the original declining amplitude and spectral energy distribution profile.

Periodic waveform generation by nonrecyclically reading lower frequency

A data compression system comprises an analog-to-digital converter for quantizing the analog signal at a first sampling frequency into a series of digital samples and a memory for storing the digital samples. A control circuit generates a sampling datum indicating a variable sampling frequency lower than the first sampling frequency as a function of the instantaneous frequency of the analog signal for selecting digital samples from the memory, reads the selected digital samples out of the memory means in response to the sampling datum, and forms the sampling datum and the selected digital samples into a data set. A series of data sets may be transmitted to a receiving end of the system or stored in a recording medium. The sampling datum is used to indicate the point at which the digital sample is converted to a corresponding analog value.

Method and system for data compression by variable frequency sampling

In a data compression system, a digital signal comprising a series of digital samples and a sampling datum associated with each digital sample is received by a decoder. The sampling datum indicates the sampling interval of the associated digital sample. The decoder includes a microcomputer for storing the digital signal into a memory (M2) and reading each digital sample and the associated sampling datum. The digital sample is divided by the sampling datum to derive a quotient which indicates the slope of the signal to be recovered. The quotient is integrated by an integrator (6b) to provide interpolation between successive sampling points, so that the original signal is approximated by a plurality of line segments.

Method and system for translating digital signal sampled at variable

A test signal is recorded on a magnetic tape prior to the recording of audio signals and reproduced to allow detection of an average value of the magnitude of the reproduced test signal. A drop-out in the reproduced signal is detected if it occurs during the process of deriving the average value. If the drop-out is not detected, a difference between the average value and a reference value is detected to adjust the signal level of the recorded test signal so that the difference reduces substantially to zero. If a drop-out is detected the average value is renewed by repeating the process of recording and reproducing the test signal.

Automatic level adjustment with means for minimizing drop-out effects

An input analog signal, such as a sound signal, is sampled by a sample-and-hold circuit, while sampling timing is variable in accordance with the amplitude variation of the analog signal. A difference between the amplitude of the analog signal and the amplitude of the output signal of the sample-and-hold circuit is detected, and the detected difference is integrated after passing through a square-law detecter. On the other hand, the average amplitude level of the input analog signal is detected to be compared with the integrated value. The sampling timing will be determined in accordance with the result of the comparison so that frequency of sampling pulses applied to the sample-and-hold circuit varies in accordance with the waveform of the input analog signal. The interval between two adjacent sampling pulses may be detected and stored together with digitally coded signals indicative of varying amplitudes of the input analog signal for recording or writing the analog signal information in a memory.

Apparatus and method for compressively approximating an analog signal

A tape reproducing system selectively reproduces programs recorded on a recording tape wound on supply and takeup reels and drives the reels at selected fast forward and rewind speeds so that the rotation speed of said reels varies nonlinearly as a function of tape diameter wound on one of said reels. To detect inter-program pauses between programs to replay the recorded programs, the duration of each sensed pause is detected. A memory stores a set of data so each datum of the set represents tape speed as a function of the varying speed of one of the reels. The stored data are read out of the memory in response to the detected rotational speed of one reel. The detected duration is corrected in response to data readout of the memory. The corrected duration is compared with a reference value to generate a control signal for replaying the recorded programs at a playback speed.

Interval detection for automatic cueing control systems

An automatic skipping control circuit includes a voltage controlled, variable frequency filter having a passband frequency variable in accordance with the voltage of a frequency control signal applied thereto. This filter is responsive to an output signal from a transducer head representative of materials recorded in a tape where a skip-mark signal is recorded in selected portions. The filter is normally tuned to the frequency of the skip mark signal when the tape is transported at normal playing speed. Upon the leading edge of a skip-mark recorded portion reaching the transducer head, the filter provides an output signal which causes the tape to be driven in the fast-forward mode, resulting in an increase in the frequency of the skip-mark signal detected by the transducer head. The frequency control signal is generated during this fast-forward mode to vary the passband frequency of the filter to correspond to the increased frequency of the detected skip-mark signal. Since the speed of the tape measured at the transducer head during the fast-forward mode varies as a function of the diameter of the convolutions of the tape wound on a takeup reel, the voltage of the frequency control signal is varied as a function of this diameter to keep track of the varying frequency of the detected skip-mark signal.

Circuit arrangement for skipping marked portions of a recording tape

A pickup arm is equipped with a photo sensor assembly for detecting non-recorded portions on a disk. The sensor is located in such a position that horizontal distance between the stylus tip and the detecting point of the sensor measured in the direction of the radius of the turntable is substantially constant throughout the possible rotational angle of the arm. The rotational angle of the arm is measured and is modified by a given angle corresponding to the above mentioned distance. When this distance deviates from a standard value on replacement of the same with another, the variation may be readily corrected by manipulating a potentiometer. Prior to performing an automatic playback, the disk is scanned by the sensor and signals indicative of the arm angles corresponding to the non-recorded portions are stored. After scanning, the arm is controlled by comparing the actual angle of the arm with the prestored angles, to place the stylus on a right position on the disk to perform automatic playback in accordance with programmed information.

Programmable automatic record player

A record disc playing apparatus comprises a horizontal drive motor for imparting a horizontal rotational force to a tone arm an address signal generating device for generating an address signal corresponding to a horizontal rotational angle position of the tone arm and a control device including a memory device for storing the magnitude of an inside force to be produced on the tone arm in correspondence with the horizontal rotational angle position of the tone arm. The address signal generating device supplies the generated address signal to the control device. The control device reads out the magnitude of the inside force from the memory device corresponding to the supplied address signal, produces a signal for cancelling the inside force at the rotational angle position of the tone arm corresponding to the read out magnitude of the inside force and supplies the same to the horizontal drive motor.

Record disc playing apparatus with automatic cancellation of inside

A tone arm control system includes first and second manually operated keys for providing input signals to a control circuit. The control circuit detects which one of the keys is operated and drives a vertical motor in the tone-arm upward direction and subsequently drives a horizontal motor in a tone-arm horizontal direction depending on which one of the keys is detected as being operated. The control circuit includes a counter which starts counting clock pulses to detect when a predetermined count is reached. During the predetermined count period the horizontal motor is energized at a low voltage to move the tone arm at a relatively low speed. When the clock count exceeds the predetermined value the speed of the tone arm is increased to allow it to speedily approach a desired position located relatively remote from the tone arm.

Variable speed tone arm control system

Apparatus for monitoring reproduced audio signals during fast playback operation comprises a bucket-brigade device for storing pieces of audio information reproduced from a recording medium at a high speed. The stored pieces of information are read out in a sequence at a slower speed than they were stored when the magnitude of the reproduced audio signal exceeds a predetermined value so that the audio information will be restored to the original pitch to be monitored. The interval for which an audio signal is stored in the bucket-brigade device may be controlled in accordance with the speed of the recording medium.

Apparatus for monitoring reproduced audio signals during fast playback

In order to compensate for differences in magnetic properties of recording tapes, a first and second audio test signals of different frequencies are generated by a variable frequency test signal source, recorded on a magnetic tape and reproduced to represent the magnetic properties of the tape at the different frequencies. The reproduced first test signal is stored in a microcomputer for comparison with the level of the subsequently reproduced second test signal to detect the difference therebetween for making an adjustment of the level of the second test signal in accordance with the detected difference through the use of a level adjusting device. The latter is thereafter held adjusted to the value at which the two test signals have an equal level of reproduction.

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Yokohama, Japan

Masatsugu Kitamura