Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A record disc playing apparatus comprises an address signal generating unit for generating address signals corresponding to horizontal rotational angular positions of a tone arm, a device for generating a rotational angular velocity signal corresponding to the rotational angular velocity of the tone arm, a circuit for controlling the rotation of a motor for driving a turntable, a control device supplied with the address signals and having a memory device from which is from which read out information corresponding to the addresses indicated by the address signals, and an attenuation circuit supplied with the rotational angular velocity signal and operating with an attenuation quantity, with respect to the rotational angular velocity signal, which quantity is varied by a signal from the control device. The rotational angular velocity signal corresponds to the quantity of any eccentricity of the record disc. The control device producing as output signals based on the information thus read out.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An automatic attenuation circuit comprises a variable loss attenuation circuit that drives circuitry for detecting the level of the output signal of the variable loss attenuation circuit. The level detector drives a periodically reset integrator, which in turn feeds a signal to a comparator, also responsive to a reference. A control circuit responsive to the output signal of the comparator controls the attenuation factor of the variable loss attenuation circuit. The control circuit, which may be a microcomputer, is so programmed that the attenuation factor of the variable loss attenuation circuit is stepwisely increased until the level of the output signal of the variable loss attenuation circuit becomes equal to or below a predetermined level.

Abstract: An automatic recording level controlling circuit comprises an audio test signal oscillator, a variable loss attenuation circuit, level detecting circuitry and a control circuit for controlling the attenuation factor of the variable loss attenuation circuit in accordance with the output of the level detecting circuitry. The level of a reproduced signal corresponding to the test signal is detected to see the deviation from a reference level so that the attenuation factor of the variable loss attenuation circuit is controlled in such a manner that the level of the reproduced signal is as close to the reference level as possible.

Abstract: An automatic bias level setting circuit for tape recorders includes a variable loss attenuator for stepwisely increasing the level of a high frequency bias signal which is superposed on a constant amplitude audio test signal. The recorded signal is detected by means of an envelope detector coupled to the playback head and fed into a resettable integrator for integrating the input signal in response to each stepwise variation of the signal to generate a series of sawtooth waves. The output of the integrator is coupled to a maximum peak detector to detect the maximum peak point of the recorded test signal to determine an optimum bias level in relation to the detected peak point.

Abstract: A system for time compression and expansion of audio signals comprises a filter for filtering the fundamental frequency component of an input signal reproduced at a speed differing from that at the time of recording, first and second memory devices for carrying out writing in or memorizing and reading out at speeds in accordance with the frequency of applied clock pulses, a control signal forming circuit for forming gate control signals and clock pulse signals of different frequency from the output fundamental frequency component of the filter in synchronism with the pitch period thereof, and gates controlled by the gate control signals to pass or not pass the output signals of the first and second memory devices. A time compressed or expanded signal synchronized with the pitch period of the fundamental frequency component of the input signal is led out through these gates.