Abstract: A transponder is selectively mounted on a vehicle. The transponder receives its operation energy through magnetic coupling with the loop coil when the vehicle comes over the loop coil, and transmits predetermined information specific to the vehicle to the vehicle detection circuit. The vehicle detection circuit time divisional performs a supply of the operation energy to the transponder and a reception of the information from the transponder, detects a presence of a vehicle in accordance with a change in the output from the loop coil, and judges from the information received from the transponder whether the detected vehicle is a predetermined vehicle.

Abstract: A time division multiplex transmission system includes: a time division multiplex encoder for supplying a master clock to a plurality of PCM digital signal sources having a same sampling requency and a same quantization bit number to effect clock synchronization and generating a time-divisionally multiplexed data signal based on a data word not D/A converted and sampled from each digital signal source; a transmission line for transmitting the multiplexed data signal from the time division multiplex encoder; and a time division demultiplex decoder for selecting a desired transmitted, multiplexed data signal and demultiplexing the selected data signal in accordance with a transmission rate before the time division multiplexing.

Abstract: An addressable PCM music broadcast receiver which decodes a contraction identification code such as an address code allocated to the receiver and transmitted by a broadcasting station which performs a pay PCM music broadcast. The receiver is capable of receiving a contracted broadcast or channel on the basis of the decoded result. The receiver further has a demonstration function of receiving a non-contracted broadcast or channel for only a given time.

Abstract: A time division multiplex transmission system includes: a time division multiplex encoder for supplying a master clock to a plurality of PCM digital signal sources having a same sampling frequency and a same quantization bit number to effect clock synchronization and generating a time-divisionally multiplexed data signal based on a data word not D/A converted and sampled from each digital signal source; a transmission line for transmitting the multiplexed data signal from the time division multiplex encoder; and a time division demultiplex decoder for selecting a desired transmitted, multiplexed data signal and demultiplexing the selected data signal in accordance with a transmission rate before the time division multiplexing.

Abstract: A time division multiplex transmission system for time division multiplexing a plurality of information signals having different sampling frequencies and transmitting the time division multiplexed signal by one transmission path. The system includes the steps of: rearranging the plurality of information signals so as to have a format of the time division multiplexed signal by use of a reference sample signal which has a frequency obtained by multiplexing the maximum frequency or a frequency higher than the maximum frequency among the sampling frequencies of the plurality of information signals by the number of the plurality of information signals; and interposting a dummy signal into the portion where there is no available information signal.

Abstract: A frequency synthesizer includes a 1/N divider for generating an address clock signal the frequency of which is 1/N times the frequency of an input signal, a memory for storing samples in a unit sine and cosine wave which is read out in response to the address clock signal to produce a frequency deviation signal, and a quadrant modulator responsive to both of the input signal and frequency deviation signal for producing an output signal the frequency of which is the difference between the input signal and frequency deviation signal. The frequency of the frequency deviation signal is varied by digitally changing N to modify the frequency of the output signal while maintaining the continuousness of the output signal phase.

Abstract: A time division multiplexed signal demultiplexing system for regenerating original signals from a time division multiplexed signal which is obtained by time-division multiplexing information signals of N channels with mutually different sampling or clock frequencies by means of a reference clock signal of a frequency equal to N times of the highest one of the sampling or clock frequencies or an even higher frequency and inserting a dummy signal and a dummy flag bit in pairs in the portion where the information signal is lacking.

Abstract: A quadrature detector comprising a double balanced differential circuit including a constant current circuit, and a phase shifter circuit. The constant current circuit comprises a plurality of transistors having their collectors connected together, their bases connected together and their emitters connected to a reference potential level through respective resistors. By the arrangement of the constant current circuit, a current density in the transistors is reduced, a noise generated by the constant current circuit is reduced and hence the S/N ratio of the quadrature detector is improved.

Abstract: An AM stereo receiver for receiving AM stereo broadcasting of an AM-PM or AM-FM system. Between an IF AM signal amplifier and an limiter is interposed a 5 or more frequency multiplier so that the frequency of a spurious signal radiated from the limiter may lie outside of the frequency range handled by the RF tuner.

Abstract: An FM/AM stereo receiver for receiving an RF FM stereo signal by FM stereo broadcasting and an RF AM stereo signal of AM-PM or AM-FM system by AM stereo broadcasting. One limiter is used both as a limiter for limiting an IF FM stereo signal in an FM stereo receiving system and as a limiter for obtaining an IF PM or FM difference signal in an AM stereo receiving system. One FM demodulator is employed both as an FM demodulator for obtaining a composite signal in the FM stereo receiving system and as an IF demodulator for obtaining an IF PM difference signal or a difference signal in the AM stereo receiving system.

Abstract: In a pulse counter-type FM detector circuit for obtaining audio signals at an output terminal by detecting FM signals in the following order through a limiter circuit, a trigger pulse generating circuit, a monostable circuit and an integrator connected to the output terminal where the monostable circuit comprises a gate circuit having at least two inputs where trigger pulses from the trigger pulse generating circuit are applied to a first one of the two inputs and a feedback signal to the other input, a differentiating circuit responsive to the output from the gate circuit, a differential inverter having a power supply and where the integrator includes an LC type low pass filter connected to the output side of the differential inverter circuit, the improvement comprising a terminal resistor connected between the power supply and the output terminal so that a part of the current flowing in the differential inverter circuit is diverted through the terminal resistor.

Abstract: A monostable multivibrator circuit is disclosed. It is characterized by comprising a time constant circuit which includes a capacitor, an amplifier circuit which receives an output signal of the time constant circuit and in which a signal amplifying transistor operates in the non-saturated state, a positive feedback circuit which is connected between the output end of the amplifier circuit and the input end of the time constant circuit and in which a signal amplifying transistor operates in the non-saturated state, and a trigger terminal which is disposed in a circuit loop constructed of the time constant circuit, the amplifier circuit and the positive feedback circuit. Further, it is characterized in that a signal which is produced by the shift from the non-conductive state to the conductive state of the signal amplifying transistor connected to an output terminal of the positive feedback circuit is supplied to the time constant circuit as a positive feedback signal.

Abstract: A monostable multivibrator including a gate circuit, a driver circuit responsive to the gate circuit, a differentiating circuit responsive to the driver circuit and a voltage comparison circuit responsive to the differentiating circuit where the gate circuit has a trigger pulse applied to a first input thereof and the output of the voltage comparison circuit is fed back to a second input thereof, and where the gate circuit, the driver circuit and the voltage comparison circuit are each non-saturating and include a constant current source and where clipping circuitry clips the output of the driver circuit to lessen the effect of noise produced by the constant current sources on the output of the multivibrator. Further clipping circuitry may be employed to prevent saturation of the gate circuit. A common voltage source may provide bias voltages for at least the above clipping circuits and a threshold voltage for the voltage comparison circuit.

Abstract: A monostable multivibrator circuit including a time constant circuit which includes a capacitor, an amplifier circuit which receives an output signal of the time constant circuit, and a positive feedback circuit which is connected between an output end of the amplifier circuit and an input end of the time constant circuit, characterized in that a trigger circuit is incorporated in a part of a circuit loop which is constructed of the time constant circuit, the amplifier circuit and the positive feedback circuit, the trigger circuit comprising an emitter-follower transistor which receives a feedback signal, another emitter-follower transistor which receives a trigger signal and whose emitter is connected to an emitter of the first-mentioned emitter-follower transistor in common, and a constant-current circuit which supplies a constant current to the emitters connected in common.

Abstract: This invention discloses a monostable multivibrator which is useful for an FM detector circuit of a pulse count system. The monostable multivibrator has a time constant circuit which includes a capacitor, an amplifier circuit which receives an output of the time constant circuit, a positive feedback circuit which is connected between an output end of the amplifier circuit and an input end of the time constant circuit, and a trigger terminal which is disposed in a circuit loop constructed of the time constant circuit, the amplifier circuit and the positive feedback circuit; and is characterized in that the amplifier circuit is a differential amplifier which is made up of a pair of transistors connected in the differential form, the transistors being connected in common through emitter resistances connected in series with respective emitters thereof. Thus, the monostable multivibrator can provide pulse signals of a fixed pulse width without being influenced by noise.

Abstract: This invention relates to a monostable multivibrator which is operated in the non-saturated state. The monostable multivibrator circuit includes a time constant circuit which has a capacitor, an amplifier circuit which receives an output signal of the time constant circuit, a positive feedback circuit which is connected between an output end of the amplifier circuit and an input end of the time constant circuit, and a trigger terminal which is disposed in a circuit loop constructed of the time constant circuit, the amplifier circuit and the positive feedback circuit; and it is characterized in that the positive feedback circuit comprises a signal amplifying transistor which has a base receiving an output of the amplifier circuit and a collector supplying a signal to the time constant circuit, and a level clamp circuit which is coupled to the collector of the transistor in order to hold a collector output potential of the transistor higher than a base input potential thereof.

Abstract: A trigger pulse forming circuit for converting a pulse signal into a trigger signal waveform is disclosed. It is characterized in that a time constant circuit is comprised in a collector output circuit of one of a pair of transistors for differential amplification and that a clamp circuit which employs a diode of the base-emitter path of a transistor is inserted between collector output circuits of the transistors for differential amplification. The input pulse signal to be subjected to the waveform conversion is impressed across the bases of the transistors for differential amplification, and the trigger pulse output signal is derived from the collector of the other of the transistors for differential amplification.

Abstract: In a monostable multivibrator including a gate circuit having first and second inputs, a differentiating circuit responsive to the output of the gate circuit and a voltage comparison circuit responsive to the output of the differentiating circuit where the gate circuit is adapted to have a trigger pulse applied to the first input thereof and the output of the voltage comparison circuit fed back to the second input thereof, the improvement in the monostable multivibrator of means for setting the reference level of the trigger pulse at the first input lower than the reference level of the output of the voltage comparison circuit fed back to the second input of the gate circuit.

Abstract: A logarithmic amplifier comprising a common-emitter type transistor amplifier circuit with an emitter resistor and a collector load. A bias voltage is applied to the base of the transistor through a diode so that the overall input-output transfer characteristic of the amplifier exhibits a logarithmic characteristic for a relatively wide range of input signals. A cascade connection of several of the basic amplifier circuits enlarges the dynamic range over which a logarithmic transfer characteristic is achieved.

Abstract: A monostable multivibrator including a gate circuit, a time constant circuit, and an inverter circuit. An input signal to the gate circuit causes the time constant circuit which preferably includes a resistor and a capacitor to charge or discharge. A signal derived from the time constant circuit is applied to an input bias circuit including an emitter follower type transistor circuit associated with a differential amplifier within the inverter circuit to control the duration of the monostable output pulse.