Showing papers on "Frequency drift published in 1969"

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.

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.

Sensor and control system for controlling gas partial pressure

Abstract: A sensor consisting of two electro-fluidic delay line oscillators generates a signal for controlling the partial pressure of a first gas in a multi-gas mixture. A sealed delay line of the first oscillator is filled with a known gas and functions as a reference oscillator. An apertured delay line of the second (sensing) oscillator is immersed in the gas mixture and the first gas flow thereto is controlled to obtain the sensing oscillator frequency equal to the reference frequency. Any difference frequency is proportional to the deviation of the actual first gas concentration from a predetermined value. A change in the partial pressure of the first gas, due to an environmental change, is compensated for by a predetermined change in the length of the sensing oscillator delay line and control of the first gas flow to regain the equal frequency condition.

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.

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.

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.

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.

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.

A Digital Frequency Synthesizer for an AM and FM Receiver

Abstract: This paper describes the design of a relatively economical, single crystal, frequency synthesizer that generates the required local oscillator frequencies for an AM and FM broadcast receiver. Selection of a station is accomplished by positioning switches to indicate the station's frequency. Fine tuning is not necessary. The receiver will not (for all practical purposes) drift, because the local oscillator frequency is crystal controlled. Low cost medium scale integrated circuits (MSI) are the building block of this synthesizer.

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.

Communications receiver employing varactor controlled tuning stages

Abstract: In a communications receiver the local oscillator output signal is converted to a voltage signal proportional to the oscillator frequency That voltage signal is applied to the voltagesensitive tuning elements in the receiver''s tuning stages to vary the tuning parameters of these elements An improved frequencyto-voltage converter effectively converts the oscillator output to the tuning voltage signal

Frequency discriminator using an intermittently phase-locked loop

Abstract: A frequency discriminator which compares a standard and an unknown frequency and generates a pulse output, the amplitude of which is proportional to the difference between the two frequencies. An amplitude sampling bridge is employed as a phase detector and is insensitive to harmonics, in that the standard frequency may be a subharmonic of the actual frequency with which the unknown frequency is to be compared. The standard frequency and the unknown frequency are delivered to the bridge in succession and individually compared with the output of an electrically controllable, variable frequency oscillator which is initially frequency-locked to the standard frequency, via a first control circuit and then via a second control circuit frequencylocked to the unknown frequency by the output pulse, the amplitude of that pulse being proportional to the frequency change of the oscillator output in proceeding from its first frequency-locked condition to its ultimate frequency.

Frequency modulated crystal controlled oscillator operable at a plurality of temperature compensated center frequencies

Abstract: A frequency modulated, solid state, crystal controlled oscillator, including a voltage variable capacitor, for use in portable transmitters wherein it is desired to operate at a plurality of center frequencies that are stable with temperature change. Any one of a plurality of center frequency determining circuits, each including a crystal operating in its parallel resonant mode, can be selected to determine a desired center frequency. Each crystal is connected in parallel with a temperature compensating network. The biasing point of the voltage variable capacitor, the net inductance of a circuit which applies the modulating voltage thereto are selected to cause the nonlinear characteristics of the crystal and voltage variable capacitor to counterbalance each other so that linear modulation is attained.

Coherent synchrotron deceleration and the emission of type-ii and type-iii solar radio bursts.

Abstract: TYPE II and type III solar radio bursts are spectacular radio emissions which accompany the flash phase of a solar flare. Appleton and Hey1 discovered these phenomena and Payne-Scott, Yabsly and Bolton2 recognized the respective slow and fast frequency drift which these emissions show. Wild3 and his colleagues, observing with a swept frequency spectrometer, found second harmonic components4 and further verified the frequency drift. The widely accepted explanation of type III bursts, that they are related to electrostatic plasma oscillations which are partially converted into transverse electromagnetic radiation by non-linear phenomena, was first put forward by Ginzburg and Zheleznykov5.

Frequency-sensitive circuit having output proportional to frequency difference between two inputs

Abstract: A slip computer for generating a DC voltage output signal proportional to the difference in frequency of two input frequency signals which utilizes a differentially charged capacitor, charged by a charging current whose average value is correlated to the frequency of one frequency input signal and discharged by a discharging current whose average value is correlated to the frequency of the other frequency input signal. Capacitor voltage as determined by a high input impedance voltage detector is a measure of frequency difference.

Frequency-modulating system for microwave solid-state oscillator

Abstract: Frequency modulation is obtained by applying a modulating voltage across a variable capacitance diode which appears in the center conductor of a cavity resonator. A direct voltage energizes a Gunn diode coupled with the resonator. Thus frequency modulation characteristics can be set irrespective of the modulation voltage and current directly influencing the oscillation output.

Sweep frequency oscillator drift correction systems

Abstract: A system for stabilizing the frequency of a voltage-controlled sweep frequency oscillator driven from a sawtooth generator is disclosed. The oscillator drives a frequency discriminator centered at the desired minimum low frequency of the oscillator. During the flyback interval of the sawtooth generator, a singleshot multivibrator is triggered which, by switching, removes the generator sweep voltage and the center frequency voltage from the oscillator and substitutes therefor a predetermined zero set voltage which returns the oscillator frequency to the same minimum low frequency just before each sweep begins. The error voltage from the discriminator, sampled during this period, is applied to a low-leakage capacitor which continuously supplies an integrated correction signal to the oscillator. The multivibrator returns to its stable state at the beginning of each sweep period and switches the oscillator back to its normal sweep control by the sawtooth generator.

Audio to uhf frequency synthesizer including a plurality of phase-locked oscillators

Abstract: A FREQUENCY SYNTHESIZER PROVIDES A PLURALITY OF SELECTABLE VALUES OF SIGNAL FREQUENCIES RANGING FROM LOW AUDIO TO UHF HAVING GOOD SHORT- AND LONG-TERM STABILITY. THE SYNTHESIZER INCLUDES A BASIC OSCILLATOR FOR GENERATING A GOOD LONG-TERM STABILIZED FREQUENCY, AN AUXILIARY OSCILLATOR PHASE-LOCKED WITH THE BASIC OSCILLATOR FOR GENERATING A GOOD SHORT- AND LONGTERM STABILIZED AUXILIARY FREQUENCY, AND A PLURALITY OF VOLTAGECONTROLLED OSCILLATORS IN PHASE-LOCKED RELATIONSHIP WITH SAID AUXILIARY FREQUENCY FOR PRODUCING DIFFERENT SELECTABLE FREQUENCIES WHICH CORRESPOND TO THE SELECTED VALUES OF SIGNAL FREQUENCIES. THE FREQUENCY CORRESPONDING TO THE MOST SIGNIFICANT VALUE OF THE SELECTED FREQUENCY IS OBTAINED BY MIXING A FREQUENCY FROM AN APPROPRIATE SELECTED ONE OF THE VOLTAGECONTROLLED OSCILLATORS WITH A SUBMULTIPLE HARMONIC OF THE AUXILIARY FREQUENCY. FREQUENCIES OF INTERMEDIATE AND LOWER ORDERS OF SIGNIFICANCE ARE OBTAINED FROM VARIOUS SUBFREQUENCY GENERATING STAGES AND ARE MIXED WITH THE FREQUENCY DERIVED FROM THE SELECTED VOLTAGE-CONTROLLED OSCILLATOR TO PROVIDE A PHASE-LOCKED CONTROL VOLTAGE FOR FINE FREQUENCY ADJUSTMENT OF THAT OSCILLATOR. AN OUTPUT MIXING STAGE MIXES THE FREQUENCY OF THE FINELY-ADJUSTED SELECTED OSCILLATOR WITH A FREQUENCY DERIVED FROM SAID AUXILIARY FREQUENCY TO PROVIDE AN OUTPUT FREQUENCY OF SELECTED VALUES HAVING GOOD SHORT- AND LONGTERM STABILITY.

Wide deviation voltage controlled crystal oscillator with temperature compensation

Abstract: A wide deviation voltage controlled oscillator having a tunable crystal filter utilizing a negative temperature coefficient coupling capacitance to produce a linear frequency change with any temperature change and a correcting diode controlled tuning voltage which is also a linear function of temperature to compensate for the linear frequency change and to automatically maintain frequency stability over a wide range of ambient temperatures

Remote drift rate compensator for frequency standards

Abstract: A drift rate compensator for secondary frequency standards of the quartz crystal type, which provides adjustment by remote control for long term rate of frequency change. Invention is particularly useful for maintaining the frequency stability of the oscillator in an orbiting satellite.

Phase-locked sweep and continuous wave generator

Abstract: As in existing frequency synthesizers, the frequency of a main tunable oscillator is controlled by being phase locked to a voltage obtained by comparing a pulse signal of comparable frequency derived by dividing the oscillator signal frequency by the necessary divisor. Binary-coded decimal switches set the divisor in steps equal to the standard frequency. A central feature of the present invention is a calibrated potentiometer supplied with a voltage that is inversely proportional to the frequency of the main oscillator and is of such a magnitude that moving the arm of the potentiometer from one end to the other will vary the frequency of the main oscillator continuously over a range which is equal to the difference between two successive frequencies determined by the switches, no matter what the frequency of the main oscillator may be. The voltage at the arm of the potentiometer is connected to the standard-frequency generator to modify its frequency a certain percentage, and a sweep signal may also be applied to sweep the standard signal over a limited band and thus sweep the signal of the main oscillator over a controlled band while still retaining a phaselocked condition.

Frequency Limit of LSA-Mode Oscillations Estimated from the Hot Electron Problems in the High Frequency Electric Field

Abstract: The frequency dependence of the drift velocity-field characteristics of n-type GaAs and the frequency limit of LSA-mode oscillations were investigated by solving the time dependent conservation equations of the electron number, momentum and energy for the lower and upper valleys. The velocity-field characteristics at high frequencies differed significantly from that for DC field and showed hysteresis loops. The maximum frequency of the LSA mode oscillation was estimated to be about 150 GHz.

External control of variable frequency oscillator

Abstract: An electronic control device comprising a pair of electrodes connected in an oscillator circuit. The electrodes are designed to be held between the hands of a subject and the oscillator output frequency is continuously variable in accordance with the conditions imposed on the electrodes by the subject.

Wideband fm demodulator

Abstract: A demodulator for frequency modulated radio frequency signals adapted to produce a DC signal indicative of the average frequency of such a signal and an AC signal indicative of the frequency deviation thereof. Such demodulator including a reference signal oscillator and a voltage controlled oscillator feeding a mixer to produce a difference frequency signal serving as a local oscillator signal to beat with the frequency modulated radio frequency signals being demodulated. The frequency of the signal out of the voltage controlled oscillator is controlled so that the beat frequency signal out of the mixer varies with changes in the frequency of the frequency modulated radio frequency signal being demodulated. The DC component of the control signal to the voltage controlled oscillator then is indicative of the average frequency of the frequency modulated radio frequency signals being demodulated and the variations in such control signal is indicative of the frequency deviation thereof.

An automatic frequency control system for a frequency modulation circuit having an asymmetric input signal

Abstract: An automatic frequency control system for a frequency modulation circuit comprising a voltage-controlled, frequency-modulated oscillator having an asymmetric input signal and a reference oscillator coupled to a comparison detection circuit, which feeds back a control voltage compensated by the mean value of the asymmetry of the signal input to the voltage-controlled oscillator so that the circuit''s output frequency is always at a harmonic of the frequency of the reference oscillator.