Abstract: Mixer arrangement (M) comprising first and second quadrature mixer stages (M.sub.1 and M.sub.2) to which quadrature mixing signals are applied from an oscillator circuit (F.sub.0), these two mixer stages (M.sub.1 and M.sub.2) being coupled to a superposition circuit (S.sub.0). To suppress interferences occurring in the output signal of the superposition circuit due to oscillator crosstalk or leakage and/or a d.c. offset of the mixer stages (M.sub.1 and M.sub.2) which are supplied with mixing signals by the oscillator cirucit F.sub.0, the quadrature components of these interferences being in phase with the quadrature mixing signals are measured by means of first and second synchronous detectors (SD.sub.1 resp. SD.sub.2) to which detection carriers are applied in an in-phase or an anti-phase relationship with respect to the quadrature mixing signals. After sign inversion these quadrature components are fed back to the inputs of the two mixer stages (M.sub.1 and M.sub.

Abstract: An oscillation circuit comprises a resonator and frequency switching means for switching oscillating frequencies of the resonator, said frequency switching means including a capacitor and an electrical switching element in series, said electrical switching element having a small capacitance as compared to that of said capacitor and a conductive voltage larger than a peak voltage of the oscillation circuit output applied across the electrical switching element. Preferably, the electrical switching element is a diode.

Abstract: A method for producing sinusoidal waves uses the steps of generating a plurality of clock signals during a 2.pi. period, using the clock signals to control the generation of 2.pi. periodical square wave pulses having preselected length and phase relationships during respective ones of the clock signals and applying the square wave pulses to a low pass filter. The reduction of pulse length as well as the phase relationship of the pulses is evaluated from a system of equations by setting the odd harmonics of corresponding Fourier series to zero or to a predetermined minimum value. A circuit device utilizing this method uses a switching amplifier operated in a binary sequence having a period corresponding to the desired sine wave period and a low pass filter connected to the output of the amplifier.

Abstract: In a circular scanning pattern tracing system, a dual scanning pattern is provided to detect pattern changes in advance of the system steering axis. Pattern detection pulses from both the scanning patterns are adjustable in length and the overlap of the pulses is used to determine whether the system should slow down.

Abstract: Charge transfer device output signals typically include an information component which is contaminated with both on-chip amplifier noise and reset noise. For reducing these noise components, the device output signal is applied to first and second synchronous detectors. The first synchronous detector is responsive to a first reference carrier signal for maximizing at its output the information component while the second synchronous detector is responsive to a second reference carrier for maximizing at its output the noise components. The synchronous detector output signals are then differentially combined so as to substantially reduce the noise components from the contaminated information component.

Abstract: An inductive loop has its frequency of oscillation controlled by means of a counter, a reference frequency source, a comparator, and an attenuator. The frequency of the loop is compared by the comparator to the frequency of the reference source to produce an error signal which controls the attenuator. The amplitude of the output signal of the attenuator is used to adjust the loop frequency to a desired value.

Abstract: A high frequency oscillation type proximity switch including an oscillating circuit having an adjusting resistor changing the oscillating state, the switch being adapted to detect an object by a decrease in the oscillation output due to the approach of the object, wherein when the oscillation output decreases, the switch detects the object while changing the resistance of the adjusting resistor to facilitate the restart of oscillation. Thus, when the object disappears after the detection of the object, oscillation is easily started, so that response to the detection of objects is improved. Further, by providing the output circuit with an integrating circuit having a time constant greater than the commercial alternating current, the oscillation is caused to be intermittent at the zero-cross point in the alternating current, thus making it possible to construct an anti-magnetic field type proximity switch which is usable even in an environment where an intense ac magnetic field is present.

Abstract: A photoelectric touch input apparatus comprises a frame placed in front of the display surface of a display device, a plurality of light-emitting elements mounted on the frame in a row along one side of a central opening of the frame to produce a plurality of light beams in parallel spaced relationship, a plurality of photosensitive elements mounted on the frame in a row along the opposite side of the opening and aligned with the light-emitting elements to receive the light beams, a transparent flat plate arranged between the display surface and the light beams and resiliently supported on the frame to be moved toward the display surface by pressure of an object touched thereto, a comparison circuit associated with the photosensitive elements to produce a first output signal indicative of the position of the object when it interrupts one of the light beams, a plurality of switches mounted on the frame and associated with the flat plate to produce a plurality of second output signals therefrom in response to m

Abstract: In order to reduce the amount of internally scattered radiant energy in an optical system having a collecting optical chamber and a secondary optical chamber, a moving aperture device is positioned in a first focal plane between the chambers; the aperture device has a continuous moving metal band that has staggered slits therein. The band is sprocket driven and cryogenically cooled to reduce thermal emission. The band can be synchronized with other scanning detectors in the optical system such as one might find in an infrared telescope used in outer space.

Abstract: An autocollimating alignment telescope automatically turns a lamp on in the autocollimating operational mode, and automatically turns the lamp off in the alignment telescope operational mode. The telescope has reticles which are replaceable in the field, as well as eyepiece and lamp housings whose mountings are interchangeable. The telescope also has an assembly for preventing jamming of the traveling lens assembly of the telescope, as well as independently operable coarse and fine adjustments for the traveling lens assembly.

Abstract: The generation waveforms is accomplished using: a computer, two random access memories (RAM), a digital-to-analog converter (DAC), two modulators, two oscillators, and a multiplier. The computer inputs a set of digital waveforms and a first control signal into the first RAM which, when directed, conducts them to the DAC. The DAC converts the digital waveform to an analog waveform, and conducts the analog waveform and the first control signal to the first modulator. The first modulator produces an output signal by single sideband (SSB) modulating an intermediate frequency carrier from the first oscillator with the analog waveform when directed to modulate by the first control signal, and outputs the analog waveform otherwise the multiplier increases the bandwidth of signals from the first modulator by multiplying its output signal. The output of the multiplier is received by the second modulator.

Abstract: A demodulator for demodulating a QAM signal which is usable in combination with an adaptive transversal equalizer. Controls over the demodulator and the equalizer are each converged to an optimum point so that the sampling points of two analog-to-digital converters of the demodulator are optimally controlled. For a limited occupied bandwidth of a carrier passband, a large amount of data may be transmitted with distortions due to delay and attenuation inherent in a transmission path compensated for.

Abstract: A transistor modulator for use in a circuit for processing video and sound signals of a video game so as to produce a composite output signal for application to the antenna input of a television receiver to produce a display of such video game. The modulator comprises an MOS transistor having a source electrode, a drain electrode and two gate electrodes. The video and sound signals and a VHF carrier signal are applied to respective ones of the two gate electrodes and either of the source and drain electrodes. The MOS transistor produces the composite output signal across an impedance which is connected to the other of the source and drain electrodes.

Abstract: A phase-locked loop is constituted by a controllable oscillator coupled through a phase detection arrangement and a low-pass filter to receive an input carrier applied to a signal input of the phase detection arrangement. In order to decrease the phase synchronization between a carrier locally generated in the loop and an input carrier, an unwanted DC offset generated during phase detection is reduced. The phase detection arrangement has first, second and third cascade-coupled mixer stages. An auxiliary mixing signal is applied from a signal generator to the first and third mixer stages. An input of one of the first and second mixer stages is coupled to the signal input of the phase detection arrangement and an input of the other of the two last-mentioned stages is coupled to an output of the controllable oscillator. The low-pass filter has a cut-off frequency lower than the fundamental frequency of the auxiliary mixing signal, and the fundamental frequency is lower than the frequency of the input carrier.

Abstract: An FM signal demodulator has a phase shifter including transversal filters for producing from a FM video signal two FM video signals which are different in phase by 90.degree. from each other, and a demodulator for detecting phase information of the FM video signal, wherein the carrier frequency is at least quadrupled prior to demodulation so as to suppress components of the FM video signal not to be included in the demodulated video signal.

Abstract: An FET oscillator wherein a bias circuit is connected to a drain of a field-effect transistor and a source circuit including a transmission line and a self-bias circuit is connected to a source of the transistor, so that the source is substantially open-circuited at an oscillation frequency and the field-effect transistor operates as a two-terminal (the gate and drain) element exhibiting a negative resistance, and wherein a resonant circuit is connected to the gate of the transistor. With the source circuit connected to the transistor source, the oscillator can have a high unloaded Q-value of Qo and a high externally-loaded Q-value of Q.sub.ext, whereby the oscillation frequency is stable. According to this oscillator, only a single bias circuit for the drain is required without the need of a bias circuit for the gate.

Abstract: In the conversion of a first delta modulated signal with a first bit rate into a second delta modulated signal with a second bit rate, a first and second digital signal derived respectively from the first and second delta modulated signals are compared together in an adding circuit (58) followed by an integration circuit (55). In this way an analog intermediary signal can be avoided and the circuit complexity is small.

Abstract: A push-pull current-fed parallel resonant oscillator includes a parallel resonant LC tank circuit with one end coupled to one terminal of a DC current source via a serially connected first diode and first switching transistor and the other end of the tank circuit coupled to said one terminal via a serially connected second diode and second switching transistor. Respective capacitors (17, 21) shunt the series connections. The tank circuit inductor includes the primary of a transformer whose secondary is part of the transistor drive circuit. The circuit parameters are chosen to provide a duty cycle less than 50% and a high voltage gain of the AC tank voltage. The transistors are controlled to delay the turn-off time of the on-transistor thereby allowing a negative voltage to develop on the opposite capacitor which in turn delays turn-off of its parallel connected transistor so as to provide a dead-time (.DELTA.t.sub.2) during the switching interval in which both transistors are simultaneously off.

Abstract: An inductorless quadrature demodulator for frequency modulated signals is disclosed. A limited FM signal is passed through an active filter (26) and a phase shift network (30) to produce a quadrature signal. The limited FM signal is compared with the quadrature signal in an EXCLUSIVE OR gate (24) and then low pass filtered (36) to obtain recovered audio. The active filter (26) includes a transconductance amplifier (60) whose center frequency can be adjusted by appropriate adjustment of the amplifier's bias current. The bias current is temperature compensated to allow operation of the demodulator over a wide temperature range.

Abstract: Microwave dielectric resonator apparatus which, for example, may be a microwave oscillator frequency stabilized by a dielectric resonator or may be a microwave filter whose critical frequency is determined by a dielectric resonator, has the dielectric resonator environmentally protected in a hermetic chamber. As the hermetic integrity of the chamber would be destroyed by having a tuning slug therein at the end of a screw threaded into a tapped hole through a chamber wall for rotation by a screwdriver outside the chamber, the tuning slug is instead located within a non-hermetic chamber at the end of a screw threaded into a tapped hole through a wall of the non-hermetic chamber serving also as an outer wall of a housing enclosing both chambers. The chambers have an interface which is transparent to microwave fields and proximate the dielectric resonator and tuning slug.