Abstract: A recording/reproducing system according to this invention for use in, for example, a digital audio tape recorder is applied to a type in which recording of an input formation signal on a recording medium is restricted, and can ensure releasing of the recording restriction by using release-signal-holding mediums on which a release signal for releasing the recording restriction is recorded. In this case, the release signal is affixed with frequency data for restricting the quantity of the information signal to be recorded on recording medium, and this frequency data is updated in such a way that the greater the number of recording the information signal on recording medium, the smaller the recordable quantity of the information signal.

Abstract: An input section inputs a recording signal to be recorded on a recording medium. An identification signal generator generates a predetermined identification signal. A processor is connected to the input section and the identification signal generator, and selectively processes the recording signal and the identification signal. A detector is connected to the input section, the identification signal generator, and the processor, and detects the presence of a recording restriction signal from the recording signal so as to control the processor in accordance with a detection result. A recording section receives an output signal from the processor, and records the signal on the recording medium.

Abstract: A recording/reproducing system according to this invention for use in, for example, a digital audio tape recorder is applied to a type in which recording of an input information signal on a recording medium is restricted, and can ensure releasing of the recording restriction by using release-signal-holding mediums on which a release signal for releasing the recording restriction is recorded. In this case, the release signal is affixed with frequency data for restricting the quantity of the information signal to be recorded on recording medium, and this frequency data is updated in such a way that the greater the number of recording the information signal on recording medium, the smaller the recordable quantity of the information signal.

Abstract: An input section inputs a recording signal to be recorded on a recording medium. An identification signal generator generates a predetermined identification signal. A processor is connected to the input section and the identification signal generator, and selectively processes the recording signal and the identification signal. A detector is connected to the input section, the identification signal generator, and the processor, and detects the presence of a recording restriction signal from the recording signal so as to control the processor in accordance with a detection result. A recording section receives an output signal from the processor, and records the signal on the recording medium.

Abstract: A sampled data generation circuit includes a voltage controlled oscillator for producing an output signal with a frequency variable according to a control voltage, a sample and hold circuit for sampling and holding an analog input signal in response to the output signal from the voltage controlled oscillator, and a control circuit for detecting the difference between two successive sampled data generated from the sample and hold circuit and supplying the voltage controlled oscillator with an output signal corresponding to the difference as the control voltage, thereby controlling the voltage controlled oscillator so that the greater the difference, the higher the frequency of the output signal from the voltage controlled oscillator is.

Abstract: A condenser microphone including an electrostatic transducer provided with at least one conductive vibrating plate and at least one fixed electrode arranged opposite the vibrating plate, and through which output voltages can be obtained in response to an acoustic input, and an impedance converter circuit connected to output terminals of electrostatic transducer, wherein said electrostatic transducer is arranged in such a way that two output voltages out of phase with respect to each other are obtained through its first and second output terminals, and said impedance converter circuit includes first and second field effect transistors of same conductivity channel type whose gates are connected to output terminals of electrostatic transducer, respectively, and whose drains are connected to a DC power supply, first and second impedance elements connected between gates of field effect transistors and ground to hold the DC potential of each gate at ground level, and an output circuit means for generating an output

Abstract: A power amplifier in which a DC power supply is coupled to a load through a switching element, a smoothing circuit, and an output amplifying element. The output amplifying element receives an input signal voltage to be amplified. A voltage detecting circuit is provided which compares a feedback voltage proportional to an output volgage of the smoothing circuit with the input signal voltage to switch the switching element, thereby varying both the power supply voltage of output amplifying element and the load output voltage in accordance with the input signal voltage. As the output voltage of the smoothing circuit is compared with the input signal voltage, the delay of the change of the power supply voltage of the output amplifying element relative to the load output voltage can be reduced, and the generation of distortion and the lowering of efficiency can be suppressed.

Abstract: The sum of an analog input signal and a positive feedback signal is applied to an A/D converter. A D/A converter device including a D/A converter and a delay device for delaying an analog feedback signal which is a signal formed by D/A converting the output of the A/D converter by one conversion operation period of the A/D converter. The positive feedback signal is formed by multiplying the analog feedback signal by a given feedback coefficient.

Abstract: A digital amplitude control apparatus for a digital audio signal in which the output voltage of a linear-type potentiometer or attenuator connected across a DC power supply is converted into a digital signal by an A/D converter, the output voltage being linearly related to the manipulated variable of the slider of the potentiometer, the digital signal is applied as an address signal to a memory which stores in memory locations thereof a series of amplitude control digital values with a desired amplitude changing characteristic, thereby reading out of an accessed location a amplitude control value corresponding to the attenuation set by the potentiometer, and a digitized audio information signal to be amplitude-controlled is multiplied by the amplitude control value read out of the memory by means of a digital multiplier.

Abstract: A noise reduction system having an encoder which compresses the dynamic range of an analog audio signal, a transmission medium coupled to the encoder, and a decoder coupled to the transmission medium for expanding and thereby restoring the dynamic range of the compressed analog audio signal. The encoder includes a voltage controlled amplifier (VCA) receiving the audio signal, a high-pass filter also coupled to the analog audio signal, a circuit for obtaining a difference between the outputs of the VCA and the high-pass filter, weighting and level sensing circuits coupled to the encoder output for sensing the level of the compressed analog audio signal, and a limiter circuit coupled to the output of the weighting and level sensing circuits and producing a control voltage applied to the VCA control input in such a manner that the ratio of the gain of the VCA and the gain of the high-pass filter at the pass band thereof does not become less than one.

Abstract: A noise reduction system including an encoder for compressing the dynamic range of an audio input signal in accordance with the amplitude thereof, a transmission medium coupled to the encoder, and a decoder having a transfer function inverse to that of the decoder. The encoder includes a first controlled amplifier circuit in which, when the input audio signal is in low- and middle- levels, sufficient emphasis is made to the signal at high frequencies, and when it is in high-level, the emphasis quantity at high frequencies is restrictive. The decoder includes a voltage-current converting circuit for converting voltage of the reproduced audio signal into current and a second controlled amplifier circuit amplifying the converted current and having a transfer function inverse to that of the first controlled amplifier circuit.

Abstract: A noise reduction system is provided with an encoder for compressing the dynamic range of an audio input signal in accordance with the amplitude of the input signal and recording the compressed one into a tape-recorder, and a decoder for expanding the dynamic range of a reproduced audio signal from the tape-recorder to the original one in accordance with the amplitude of the reproduced audio signal. The encoder includes a first controlled amplifier circuit in which, when the input audio signal is low- and middle-levels, sufficient emphasis is made to the signal at high-frequencies, and when it is in high-level, the emphasis quantity at high-frequencies is restrictive. The decoder includes a second controlled amplifier circuit having a transfer function related to the character of the first controlled amplifier circuit substantially in inverse-function manner.

Abstract: A noise reduction system is provided with an encoder for compressing the dynamic range of an audio input signal in accordance with the amplitude of the input signal and recording the compressed one into a tape recorder, and a decoder for expanding the dynamic range of a reproduced audio signal from the tape recorder to the original one in accordance with the amplitude of the reproduced audio signal. The encoder includes a first controlled amplifier circuit in which, when the input audio signal is in low- and middle-levels, sufficient emphasis is made to the signal at high frequencies, and when it is in high-level, the emphasis quantity at high frequencies is restrictive. The decoder includes a second controlled amplifier circuit having a transfer function related to the character of the first controlled amplifier circuit substantially in inverse-function manner.