Showing papers on "Voltage-controlled oscillator published in 1969"

Oscillator and oscillator control circuit

Abstract: An oscillator circuit adapted particularly for use with transducers for producing energy in the ultrasonic frequency range in which a combination of feedback signals representative of the voltage across the transducer and the current through the transducer are used to more precisely lock the oscillator to the resonant frequency of the load to thereby provide improved power transfer from the oscillator to the transducer. A current control circuit is also provided to control the amount of shock delivered by the transducer.

Frequency control of a pulsed parametric oscillator by radiation injection

Abstract: A singly resonant optical parametric oscillator (SRO) is pumped by a high power, pulsed source and is tuned approximately to a predetermined desired frequency. Radiation of that frequency is injected into a mode of the SRO from a stabilized, low-power injection source. The output of the SRO is a pulsed, high-power signal with frequency equal to the predetermined frequency to a high degree of accuracy.

Radio frequency standard and voltage controlled oscillator

Abstract: A radio signal controlled oscillator is provided as a local frequency standard by synchronizing the oscillator using a phaselock servosystem comprising a long term integrating device as a voltage variable capacitor in the resonant circuit of the oscillator. The device consists of two columns of mercury separated by a substantial gap of electrolyte in a chamber made of dielectric material. Upon comparison of the oscillator signal with the radio signal, any error signal developed is applied across the electrolyte gap to the mercury column to transfer mercury from one to the other by the process of electrolysis. Conductive material wrapped around the chamber serves as a second plate of a capacitor for each of the columns one of which is used as part of the voltage variable capacitor. Means is provided for detecting the loss of the radio signal to interrupt any further change in the variable capacitor until the radio signal is restored.

Combining network providing compensated tuning voltage for varactor

Abstract: A control circuit for an indirect frequency synthesizer which combines a plurality of control functions into a single compensated tuning voltage for the varactor control element of an associated voltage controlled oscillator. The combining circuit includes a resistor network for summing phase control and modulating signals, and a variable resistance circuit for generating a coarse steering signal. The summing network is resistively connected to the variable resistance circuit to form a variable impedance resistor divider operative to attenuate the combined phase control and modulating signals in a manner inversely related to the magnitude of the coarse steering signal and to combine the attenuated control signals with the coarse steering signal and to combine the attenuated control signals with the coarse steering voltage to provide the varactor tuning signal. More specifically, the attenuation provided by the impedance divider is operative to substantially compensate for the variation in voltage versus frequency sensitivity of the varactor with changes in the coarse steering voltage.

Frequency modulation of a millimeter-wave IMPATT diode oscillator and related harmonic generation effects

Abstract: In this paper we report the performance of a continuous wave millimeter-wave IMPATT diode oscillator with a wide-band tunability. The diode is mounted in an iris wafer circuit; its oscillation frequency can be modulated either by a varactor diode or by direct modulation of the IMPATT diode bias current. The oscillator has been successfully used as a millimeter-wave frequency deviator in an experimental pulse code modulation millimeter-wave system. We also report detailed measurements on subharmonic frequencies in IMPATT diode oscillators. Experimental results show that wide frequency tunability can be obtained with a circuit which provides an “idler” resonance at one-half the fundamental transit-time frequency. The results also show that by providing “idler” resonances at both the transit-time frequency and at one-half of the transit-time, the oscillation at 3/2 the transit-time frequency is enhanced and yields a useful output power of 2 mW at 86 GHz.

Voltage-controlled oscillator

Abstract: The disclosure is directed to a voltage-controlled oscillator using a pair of integrators coupled to a pair of voltage comparators and wherein the outputs of the voltage comparators control a flip-flop. The output from the flip-flop is used to alternately control the individual ones of the integrators to operate in response to an analog input signal so as to produce an output signal from the flip-flop which has a frequency in accordance with the input signal to the integrators. In addition, the invention includes the use of a feed forward signal which is coupled to the comparators to control the time of operation of the comparators to compensate for fixed delays in the system.

Frequency modulated phase-locked oscillator having a low- and high-frequency response

Abstract: In a phase-locked loop frequency modulator, the signal applied to the reference input of the phase comparator is a frequencymodulated signal, modulated at the same rate as the output signal, for low-modulating frequencies. For higher modulating frequencies, the signal applied to the reference input of the phase comparator is a constant frequency source.

Frequency stabilization of continuously tunable oscillators

Abstract: A voltage controlled oscillator with a controllable phase shifter and a delay line connected in series with the output of the oscillator. A phase discriminator measures the phase difference between the output of the oscillator and the output of the delay line and feeds back a difference signal which, suitably conditioned, dynamically stabilizes the frequency of the oscillator.

Pseudo-random frequency generator

Abstract: A binary pseudo-random frequency generator in which a shift register is continuously strobed by a clock and has its informational content altered in accordance with its acquired state A variable count divider counts down to zero from a number set therein from information received from the shift register at the divider zero count in response to frequency signals received from a voltage controlled oscillator Divider zero counts are also compared in a phased lock loop with a reference frequency to set the voltage controlled oscillator frequency

Variable frequency control system and data standardizer

Abstract: A variable frequency oscillator feedback control system performs a frequency control function and a data relocation function. The oscillator is made to follow the frequency of random input data and individual incoming data pulses are relocated in time to correspond with the time slots defined by the oscillator output pulses. The feedback loop contains a novel DC logic phase comparator and data standardizer. The phase comparator controls the frequency of the oscillator while the data standardizer relocates the data pulses to the time slots of the oscillator pulses.

Circuit for phase locking an oscillator to a signal modulated in n-phases

Abstract: A phase synchronizing circuit includes a voltage-controlled oscillator wherein the oscillatory frequency changes around a center fo by control against a digital input signal being modulated in n-phases of which the carrier frequency is f0; nphase detectors; n-comparators; a logic circuit having n-input terminals which performs an ''''exclusive or'''' or ''''negation of exclusive or'''' operation; and, a low-pass filter. The input signal, an output of the oscillator and the n-phase detectors are connected so as to detect PHASE COMPONENTS IN THE INPUT SIGNAL WHEREIN AN OUTPUT OF THE OSCILLATOR IS THE REFERENCE PHASE. The outputs of each detector are applied to the n-comparators respectively, the outputs of the n-comparators to n-input terminals of the logic circuit, and the output of the logic circuit is connected so as to control the oscillatory frequency of the voltage-controlled oscillator through the low-pass filter.

Frequency-lock circuit

Abstract: A circuit for locking the frequency of an oscillator to that of a received signal. The latter is amplified, clipped and differentiated before being fed to a phase-lock loop comprising, in series, a phase comparator, low-pass filter, gating means, memory means and a voltage-controlled oscillator (VCO). The output of the VCO is fed back through a frequency divider to the phase comparator. The comparator produces a symmetrical output when the circuit input and output frequencies are equal and an unsymmetrical output when the frequencies differ. The unsymmetrical output provides a DC level when filtered, which is used to control the VCO frequency to bring it back to the input frequency after frequency division. The output of the frequency divider is also the output of the frequency-lock circuit.

System for controlling the speed of a motor utilizing pulse width modulation

Abstract: An input voltage is summed with a voltage picked off from a polyphase motor for driving a voltage-controlled oscillator. The frequency of the output signal from the oscillator is dependent on the magnitude of the summed voltage. The pulse width is modified within a predetermined range as a function of the frequency and is converted into three phase signals which are summed and applied to the stator windings of a motor. The signal across the windings has an optimum voltage and frequency ratio which is varied when the speed of the motor is changed.

Step width regulated dc/dc converter

Abstract: A feedback regulated DC/DC converter is disclosed. More particularly, an unregulated master oscillator feeds square waves into one core of a dual-core transformer, and a slave oscillator (whose output amplitude is a predetermined fraction of the master oscillator''s output amplitude) also feeds square waves into the other core of the transformer. A sample of the transformer output after it has been rectified and filtered is compared against a reference value and the difference between the output value and the reference value produces an error current which is fed into a delay circuit. The delay circuit will then synchronously adjust the output phase of the slave oscillator. Thus, the average voltage appearing across the secondary of the dual-core transformer is varied by adjusting the relative phase between the master and the slave oscillator. Since the slave oscillator operates at only a small percent of the master oscillator''s output, step-width modulation, rather than the standard pulse width modulation, results.

Radar apparatus and systems

Abstract: A radar apparatus comprised of a transferred electron oscillator in association with a cavity resonant at the frequency of oscillation of the transferred electron oscillator. A mixing diode in the signal path between the transferred electron oscillator and a transmit/receive aerial yields a difference output. The frequency of the radar may be modulated or swept by enclosing the transferred electron oscillator within a ferrite collar whereby changing the applied voltage to the transferred electron oscillator changes the frequency of the radar.

Frequency synthesizer system

Abstract: A frequency synthesizer system is disclosed utilizing phase registration for frequency regulation and affording smooth frequency changes in accordance with a control signal. The output from a voltage controlled oscillator is tallied (cyclically) by a digital counter, the contents of which is periodically compared with the contents of an accumulator that is incremented periodically to define the desired frequency, e.g. cycles per second. The comparison provides a primary regulation signal for combination with a change-commanding signal (provided from an integrator) for application to the oscillator. The slope of the integrator output is proportional to an applied control signal and that output is monitored to detect a change that is equivalent to a digital quantity, whereupon the integrator is reset and the accumulator is incremented by the digital quantity. Fractional quantities are also accommodated by the system.

Color video signal correction for mechanical variations in magnetic recording system

Abstract: A color signal correction system for a video magnetic tape recorder removes differential frequency changes and differential phase shifts. The system comprises a trigger oscillator which oscillates in phase with a burst signal taken out of the color signal. A first means frequency modulates a color signal filtered out of the reproduced color video signal, and a second means frequency modulates the oscillation frequency of the oscillator. The output signals of the first and second frequency modulation means are mixed to produce a signal having the differential frequency removed therefrom. Control means is provided to control the natural resonant frequency of the tank circuit of the trigger oscillator, the control corresponding to the differential frequency changes and the differential phase shifts.

A New Microwave Amplifier for Multichannel FM Signals Using a Synchronized Oscillator

Abstract: Because of the excellent results of the noise-loading test on an IMPATT oscillator that is phase-locked to an external FM driving signal, a new microwave amplifier for multichannel FM signals using a synchronized oscillator is proposed. An IMPATT oscillator, injection-synchronized with an FM signal, is regarded as an amplifier and its noise characteristics for multichannel signals are evaluated with the noise-loading method as recommended by the International Radio Consultative Committee. The results show that when this oscillator satisfies the noise characteristics for 960 telephone message channels, it assures a gain of approximately 15 dB at 11 GHz, and in this sense, this oscillator can be regarded as an amplifier for multimessage channels. The degradation of SNR of this amplifier is less than 2 dB. This excellent result is obtained because of the following. In the video band, the modulation suppression of an FM driving signal in the injection-synchronized oscillator, such as the IMPATT, is very small, while the oscillator noise, which dominates the entire output characteristic, is considerably reduced by the synchronizing action of the oscillator. This amplification continues up to the high-frequency range in which this principle of operation applies.

Frequency modulated solid state crystal oscillator providing a plurality of center frequencies

Abstract: Frequency modulated, solid state oscillator which oscillates at any one of a plurality of center frequencies in response to the positioning of a selector switch that connects a selected center frequency determining circuit to the oscillator. Each of the center frequency determining circuits includes a crystal operating in its series resonant mode, an inductor for tuning, and a resistor for suppressing undesirable crystal operation. Frequency modulation is accomplished by impressing a modulating voltage across a varactor included in the frequency control circuit of the oscillator to thereby change its capacitance and consequently change the frequency of oscillation.

Variable frequency oscillator and modulator circuits including colpitts transistor and feedback transistor

Abstract: The basic variable frequency oscillator circuit includes a transistor connected in a Colpitts configuration. An effective tank circuit capacitance is varied in accordance with a control signal to vary the circuit oscillation frequency. When the effective capacitance is provided by the transistor base-emitter capacitance, the frequency variation may be achieved by varying the transistor emitter current or the collector-base voltage. Alternatively, the effective capacitance may be varied by varying the transconductance of a second transistor coupled in a feedback arrangement with the Colpitts transistor. Frequency modulation may be achieved when a modulating voltage is used as the control signal. Circuit variations involving phase locking of the feedback employing embodiment onto an input signal include a frequency demodulator, a phase modulator and an amplitude modulation limiter. Further variations include a harmonic signal generator and frequency multiplier/divider circuits.

Variable speed closed loop digital servosystem

Abstract: An analog, condition responsive, bidirectional stepper motor position servosystem in which the rate of response is a function of the absolute value of the instantaneous error signal. Clocked gates are utilized in lieu of AND gates to prevent the application of excessive pulses from the VCO to the motor and step integrity is insured by the utilization of a filter circuit at the input to the VCO.

Voltage controlled oscillator in which capacitive diodes become resistive during portions of each cycle

Abstract: By varying the voltage applied to two oppositely poled varactors, placed in series in the resonant circuit of a microwave oscillator, the portion of each oscillatory cycle in which each varactor acts as a capacitor as opposed to a low resistance, is varied, thereby linearly varying the oscillatory frequency of the circuit.

A Current‐to‐Frequency Converter for Astronomical Photometry

Abstract: A simple current‐to‐frequency converter has been developed which works directly with photomultiplier currents. It has full scale input current ranges of 3×10−10 to 3×10−6 A. The feedback pulse is a square pulse that is clocked on and off by a continuously running oscillator. Drift in the oscillator frequency is compensated if the oscillator also serves as the time base of the counter used to count the pulses. With oscillator frequencies up to and including 20 kHz the linearity is 0.01% or better and the drift less than 0.01% of full scale per hour.

Self calibrating analog to digital converter

Abstract: The method and apparatus for providing a self-calibrating ADC of the type which utilizes a voltage controlled oscillator in conjunction with a counting register to translate an analog signal into time domain. A second counting register, a fixed frequency pulse source, and zero and full scale reference voltages are used to generate span and zero calibration factors to any desired accuracy.

Method and apparatus for controlling one oscillator by another

Abstract: A first high frequency stable oscillator is used to control a second lower frequency oscillator by the method of sensing the attainment of a peak value of one of the oscillating parameters of the second oscillator, applying a constraint to that parameter to inhibit temporarily the oscillation of the second oscillator, and releasing the constraint when the first oscillator next reaches a datum position in its cycle of oscillation.

Voice transmission and receiving system employing pulse duration modulations with a suppressed clock

Abstract: A voice transmission system including coded voice information using pulse duration modulation (PDM) with a suppressed clock and wherein this suppressed clock pulse duration modulated voice signal is used to modulate a phase shift keying modulator (PSK). The receiver includes a phase shift keying demodulator which feeds a limiter having a wide bandwidth so as to achieve the highest possible processing gain. The receiver also includes a voltage controlled oscillator which is fed an error signal derived from an integrator so as to produce an output signal from the voltage controlled oscillator to replace the suppressed clock.

Phase locked loop receiving system with improved signal acquisition

Abstract: An improved phase locked loop of the type used in systems for receiving and measuring a variable frequency signal, such as a Doppler signal from a Radar illuminated moving target. A unique self-calibrate loop is provided to compensate for VCO (voltage-controlled oscillator) drift, and a memory hold keeps the VCO on means frequency during an automatic search interval. The result is that the VCO sweep used in acquisition may be more optimally pre-biased and acquisition or reacquisition of signals is accomplished more rapidly.

Torsional vibration densitometer

Abstract: A direct measurement of density of a fluid is made by coupling the fluid to a rod under torsional oscillation. The frequency of torsional oscillation is maintained at the resonant frequency by sensing the phase difference between the stress in the rod and the current in a driving coil which produces the force to sustain torsional oscillation in the rod. The stress is measured by strain gauges which provide the electrical signal for phase comparison with the driving coil current. The frequency of the current is controlled by a voltage controlled oscillator whose input is derived from the phase comparison to provide a frequency which is at the resonant frequency of the oscillatory rod as modified by the density of the fluid to which it is coupled. The precise relationship between fluid density and resonant frequency is established by calibration.

Transducer controlled variable frequency wien-bridge oscillator

Abstract: THE FREQUENCY SELECTIVE BRIDGE OF A STANDARD WIENBRIDGE OSCILLATOR IS PROVIDED WITH AN ADDITIONAL PHASE SHIFTING NETWORK COMPRISING A CAPACITOR AND A LINEARIZED TRANSDUCER. THE TRANSDUCER EXHIBITS IMPEDANCE CHANGES RESPONSIVE TO PHYSICAL VARIATIONS OF A FUNCTION BEING MEASURED, AND THE OVERALL CIRCUIT DIRECTLY CONVERTS SUCH TRANSDUCER IMPEDANCE VARIATIONS INTO A LINEAR DIGITAL FUNCTION IN A COMPUTER COMPATIBLE FORMAT WITHOUT THE USE OF A VOLTAGE DRIVEN ANALOG-TO-DIGITAL CONVERTER MODULE.

Binary information receiver for detecting a phase modulated carrier signal

Abstract: A receiver for detecting phase reversed binary information wherein the phase reversal is accomplished linearly over one clock period by slightly increasing or decreasing the carrier frequency. A variable frequency local oscillator tuned to the carrier frequency is mixed with the phase modulated carrier signal and then averaged by a first filter. When the oscillator is at the proper phase, the output of the first filter will be a binary signal. A pair of feedback loops detect and compare in a subtractor and a second filter the rectified outputs of a pair of mixers which beat the phase modulated carrier signal with plus and minus 45* components of the oscillator signal. When the oscillator is at the proper phase, the energy from both mixers in the feedback loop will be equal. When the oscillator phase is incorrect, the energy in the loops will be different and the output of the second filter will then increase or decrease slightly the oscillator frequency until the proper phase is reached.