Abstract: An automatic frequency control system for use in a frequency converter of a time division communication system, wherein the nonmodulated portion contained in the burst signal is selectively frequency discriminated. The frequency discriminated output is held for a certain period of time and then used as the oscillation frequency control signal of a local oscillating means.

Abstract: The phase detector of a phase-lock loop comprises a double balanced mixer that compares the phase of the output signal of the loop oscillator with that of a reference signal and combines the resultant error control voltage with a constant sweep voltage that is stepped at a variable rate. When the loop is out of lock, a counter circuit increments the contents thereof for every n excursions of the difference frequency signal from the phase detector that exceed a prescribed threshold level. A D-A converter converts each unique count to a corresponding constant amplitude step of the stepped sweep voltage. Since the difference between the frequencies of the oscillator and reference signals decreases as the loop approaches lock, the rates at which the counter is incremented and the sweep voltage changes value also decrease. Thus, the loop is swept at a slower rate as the frequencies of the reference and oscillator signals converge.

Abstract: A voltage controlled oscillator includes a VCO chip that is a monolithic circuit with a Gunn diode and varactor diode intercoupled by a resonant circuit. A detector/discriminator/power divider chip is coupled to the VCO chip through a directional coupler and is a monolithic circuit having a pair of discriminator diodes and amplitude detector diode on a semi-insulating substrate with associated circuit components. Connected-together electrodes of the discriminator diodes are connected to one output of the power divider. An electrode of the amplitude detector diode is connected to the other output of the power divider. Stagger-tuned resonant circuits are coupled to the other electrodes of the discriminator diodes. Conducting portions forming low pass filters couple the amplitude detector diode and the discriminator detector diodes to respective outputs.

Abstract: In satellite telephone communication equipment, the phase detector of a phase-lock loop compares the phase of a master oscillator signal from the loop oscillator with that of a pilot tone signal and produces an error control voltage which it combines with a constant sweep voltage that is stepped at a variable rate. When the loop is out of lock, a first count of the number of excursions of the beat or difference frequency signal from the phase detector that exceed a prescribed threshold level is generated, a second count is incremented for every n counts in the first count, and a constant amplitude step of the stepped sweep voltage is produced for each unique value of the second count. The steps in the sweep voltage occur at a variable rate that is related to the difference frequency of the beat signal. Since the difference between the oscillator and pilot frequencies decreases as the loop approaches lock, the rate at which the sweep voltage is stepped also decreases.

Abstract: A system and method for continuous tuning of a YIG oscillator over its entire operating range by control of a resolver in a feedback loop around the oscillator. The resolver and a delay line form a phase shift network the output of which is compared in phase with the output of the oscillator, which is also coupled to the input of the resolver, and the phase-difference signal resulting from the phase comparison is coupled to an integrator connected in turn to the tuning signal input of the oscillator. Repetitive operation of the resolver over its operating range enables continuous tuning of the oscillator over its entire operating range.

Abstract: A phase-locked loop capable of generating a plurality of stable frequncy signals. This loop includes a plurality of voltage controlled oscillators which are sequentially coupled to the output of a phase sensitive detector by a multiplexer. RF switches then sequentially couple, in synchronism with the multiplexer, the oscillator outputs to a programmable divider which, in turn, is coupled to an input of the phase sensitive detector, the other input thereto being coupled to a reference oscillator. The dividing factors for the programmable divider are inputted thereto, in synchronism with the multiplexer, from a memory.

Abstract: A frequency synthesizer includes frequency reduction means which includes a pulse swallow circuit PS which cancels cycles from the frequency Fo under the control of a rate multiplier RM. To prevent phase jitter at the output of phase comparator PC due to the cancelled cycles, a compensation signal HP is derived from a swallow command signal A and from a multiplying fraction n/x of the rate multiplier. In order to keep the DC level of the signal HP constant, the signal HP is bidirectional with respect to a mid-point voltage level and the total area of the pulses in one direction is the same as the total area of the pulses in the other direction. The invention is applicable to both phase locked loop synthesizers (FIG. 2) and direct synthesizers (FIG. 11).

Abstract: The clock signal output of an oscillator is synchronized to the frequency of a data signal by detecting the phase difference between the two signals. The control signal signifying the difference is quantized into a number of standard units and a remainder. The remainder is accumulated and, when it is equal to a standard unit, added to the number signal signifying the number of standard units. The frequency of a fixed frequency oscillator is then adjusted in a direction tending to nullify the number signal.

Abstract: A line synchronizing circuit for a picture display device comprising a phase control loop for controlling a line oscillator. The circuit comprises a coincidence detector for establishing that a phase difference between the incoming line synchronizing signal and the oscillator signal is less than a predetermined value. When the output signal of the coincidence detector reaches a reference value indicating the presence of an incoming signal, the loop gain and the pull in rate, respectively, of the control loop are switched to a higher value than prior thereto. In addition, the circuit comprises a signal prolonging element which subsequently maintains the control loop in this state during a predetermined period of time. Thanks to this measure the oscillator can be pulled-in with absolute certainty.

Abstract: A variable frequency oscillator 10 has an output frequency Fo responsive to a voltage input Vo derived from an analogue integrator 11 controlled by potentiometer 15, 16, the frequency Fo being displayed on frequency meter 19 having a ghost least significant digit. A converter 24 responds to the digit of a digital output fed to a digital to analogue converter 20 providing an error voltage Ve whose magnitude is proportional to the deviation of the digit from a datum, e.g. 5, and whose polarity depends on whether the deviation is + or -. The voltage Ve is also fed to the integrator 11 to control the voltage Vo.An arrangement is also described in which the voltage Ve is derived from the divider chain of a gate period generator controlling a frequency counter whose input is Fo.

Abstract: A digital counter is phased locked to a reference frequency by a voltage trolled oscillator which causes the counter to increase its count rate or decrease its count rate in accordance to the presence of a one or a zero on the most significant bit of the counter at the halfway point of one cycle of the reference frequency. The counter is reset at the end of the cycle of the reference frequency. A single microprocessor which can assess this most significant bit (MSB) and vary the oscillator output, can in this manner control any number of independent phase lock loop circuits.

Abstract: In a control circuit for a voltage-controlled oscillator including the combination of: (a) a source of D.C. power, the voltage out of such source being adjustable in discrete steps to provide a coarse frequency control signal; (b) a control loop, responsive to the signal out of the voltage-controlled oscillator, to provide a fine frequency control signal; and (c) a summer to combine the coarse and fine frequency control signals into a single frequency control signal for the voltage-controlled oscillator, an improvement is shown wherein the control loop comprises an interferometer wherein noise extant on the signal out of the voltage-controlled oscillator is degenerated by dividing a portion of such signal into a reference path, a delayed path and a parallel path, the signals in the latter two paths being processed to produce an amplitude corrected signal for combination with the signal, shifted by 90.degree., in the reference path, finally to produce the fine frequency control signal.

Abstract: A frequency synthesizer having a delay line for a controlling element. The output frequency of a voltage controlled oscillator (VCO) is sampled with a directional coupler and input to an in-phase power divider. The first output of the power divider is input to a delay line to provide a delayed signal. The delayed signal and the non-delayed signal from the second output of the power divider are input to a phase detector. The output of the phase detector is a DC voltage representative of the phase difference between the delayed signal and the non-delayed signal. An analog gate inputs the phase detector output to an oscillator driver that controls the VCO. When the phase difference deviates from a predetermined level the oscillator driver outputs an error voltage to adjust the VCO until the proper phase difference is achieved which will be a condition of phase lock wherein the output frequency is phase locked to the delay line.

Abstract: A frequency shift responsive metal detector having a sense oscillator coupled with an inducer loop. When the inducer nears a metal object, the effective inductance is changed which correspondingly shifts the natural frequency of the sense oscillator. The sense oscillator couples with a frequency shift detector. The detector produces a d.c. feedback signal which is proportional to the sense oscillator shift and acts therewith to re-establish the oscillator to it's original natural frequency by way of a voltage controlled reactance. The detector also produces a d.c. output that serves to drive an audio frequency rate voltage controlled oscillator wherein the pitch, or resultant frequency therefrom produced is proportional to the effect of the metal object on the inducer loop. A d.c. signal from the detector also serves to drive a visual indicator, such as a meter.

Abstract: Data signals which vary between first and second levels are applied to an operational amplifier by a timing signal produced in response to data signal transitions. The operational amplifier is connected to produce a nominal voltage in the absence of data signals, and to produce first and second voltages above and below the nominal voltage by equal amounts in response to the first and second data levels. The voltages so produced are used to control the frequency of an oscillator.

Abstract: A delay line frequency discriminator having application to microwave equipment and particularly used for stabilizing an oscillator, including a first coupler supplied by the oscillator and connected to a second coupler by means of two electromagnetic transmission lines, wherein one of the transmission lines introduces a delay time .tau. compared with the other line. The second coupler delivers a sum signal which is the stabilized output signal of the oscillator and a difference signal to a third coupler which is also fed with a sampled portion of the output signal of the oscillator and supplies the oscillator via a detector and an amplifier.

Abstract: A remote control circuit which operates on a frequency basis and essentially with analog signals. The remote control circuit includes at the transmitting end a controlled oscillator, a frequency/direct signal converter and a comparator connected together into a frequency control loop. A transmitter is also provided which is fed by the oscillator of the control loop. A control path including a frequency signal source and a frequency/direct signal converter is provided at the transmitting end and receives its input signal from the frequency signal source. The converter of the control path is connected with the one input of the comparator of the control circuit. At the receiving end there is provided an amplifier, a frequency/direct signal converter and an evaluation circuit.

Abstract: Positive feedback is applied from the piezo-electric vibrator in an ultrasonic nebulizer to the control electrode in the oscillator circuit for improved performance.

Abstract: A signal of frequency value F.sub.IN is coupled to a discriminator and to one terminal of a voltage controlled oscillator (VCO) tuned to operate at a range of frequencies about F.sub.IN .div.N where N is a nonunity positive integer. The discriminator produces a voltage proportional to frequency F.sub.IN which is scaled and applied to a control terminal of the VCO to cause it to be tuned to approximately F.sub.IN .div.N. The signal of frequency F.sub.IN applied to the VCO causes it to be injection locked to frequency F.sub.IN .div.N.

Abstract: The numbers of cycles in a received signal including Doppler frequency spread are counted (36) modulo a base value much smaller than the number of cycles in such received signal during a predetermined measuring interval for thereby averaging out the effects of such frequency spread in the counter output. That output is utilized to control the frequency of a local oscillator (26) to lock it to the frequency of the received signals. The actual duration of the measuring interval is set (39) in accordance with a signal provided from the oscillator. Also shown are circuits (45, 23) for causing the oscillator initially to lock to a radio system master reference frequency and thereafter to lock, in a narrow frequency band, to a pilot frequency of a specified information channel.

Abstract: A low phase noise signal source is disclosed which incorporates a voltage controlled oscillator (VCO) and a feedback network that, in effect, demodulates the VCO output signal and supplies negative feedback representative of the VCO signal noise to the VCO frequency control terminal. The feedback network includes a frequency discriminator of the type wherein a time delay network is connected to one input port of a phase detector, with the VCO output signal being supplied to the time delay network and the second input port of the phase detector. A variable phase shifter, responsive to the signal supplied by the phase detector, is included in one of the phase detector input paths to cause a zero crossover of the frequency discriminator transfer characteristic to occur at the frequency to which the VCO is tuned.

Abstract: A frequency detector and method for use in timing and carrier recovery applications. In a timing recovery application, the circuit includes means for generating a variable frequency periodic clock signal corresponding to an input data signal, means for determining whether successive data transitions of the data signal occur during first and second predetermined portions of successive cycles of the clock signal and means for changing the frequency of the clock signal when successive data transitions occur during different ones of the predetermined portions.

Abstract: A circuit for controlling the frequency of a pulse generator associated with a microprocessor that is connected to power line frequency, uses an RC-stage which is connected ahead of the pulse generator as the frequency-determining element and which has a resistor 19 that is variable by a control signal derived from the microprocessor. The control signal is obtained by comparing the power line frequency and the pulse frequency with one another.

Abstract: It is known to generate mircowave frequencies by locking the fundamental output frequency of a microwave oscillator to a multiple or sub-multiple of the output frequency of a highly stable crystal oscillator operating at a lower frequency than the microwave oscillator. Phase-locked loops are used together with frequency multipliers or dividers. One problem is that the frequency lock range decreases as successively higher and weaker harmonics are used for locking. This limits the practical harmonic locking range to multiples of approximately less than ten. The present invention eliminates this problem and allows microwave signals which have a frequency greater than 10 times the reference frequency to be phase locked without an impractical reduction of the capture range. As well, in conventional phase locked loop systems which use multipliers, fm modulation which is intentionally injected must have a modulation index less than 1.0.

Abstract: Disclosed is a feedback regulated oscillator which comprises a reference signal source, a variable local oscillator, a converter responsive to the variable local oscillator for developing a signal, compatible with the signal of the reference source, having a magnitude which is responsive to the frequency of the local oscillator, and a comparator, responsive to the reference signal source and to the converter, for controlling the frequency of the variable local oscillator.

Abstract: The present invention deals with an ultrasonic wave generating apparatus with voltage controlled filter, comprising a phase comparator which detects a shifted value from a predetermined phase difference between a driving voltage or a driving current of an ultrasonic transducer and a vibratory velocity signal, and a voltage-controlled band-pass filter which is controlled by the output of the phase comparator and which is provided in a feedback loop from the vibratory velocity signal to an input of a driving amplifier of the ultrasonic transducer, wherein the oscillating frequency is changed while following the resonant frequency of the ultrasonic transducer, so that stable operation is materialized without developing abnormal oscillation in subresonant frequencies and permitting very small following error.

Abstract: In a synthesizer system having a reference oscillator selectively operable in either a voltage-controlled or an injection-locked mode, a circuit for effecting the appropriate mode of operation. The circuit includes an analog gate coupled between the output of a crystal oscillator and the input of the reference oscillator. The analog gate is driven by a logic element responsive to a plurality of signals indicative of specific operating conditions. In particular, the circuit assures that the reference oscillator is coupled to the crystal oscillator, that is, the reference oscillator operates in the injection locked mode, while the synthesizer PLL achieves acquisition.

Abstract: An automatic switching control circuit is responsive to a command signal as derived from manual tuning operation to change the operating modes of a feedback-controlled system such as automatic frequency control circuit, and includes a first impedance element, an inverting amplifier and a second impedance element in a series circuit between an input terminal to which an error signal from the feedback-controlled signal is applied and an output terminal from which a compensation signal is applied to a modulating element of the feedback-controlled system. A third impedance element is connected between the output terminal and a reference terminal. A switch is provided to establish a short circuit path between the input of the inverting amplifier and the output terminal. The voltage across the third impedance element automatically reduces to substantially zero voltage level in response to the presence of the short circuit path so that the feedback control is suspended.

Abstract: An electronic timepiece having a main oscillator circuit including a first quartz crystal vibrator as a time standard and also having a secondary oscillator circuit including a further quartz crystal vibrator as a time standard for reducing the affect of temperature on the accuracy of the timepiece by utilizing the different temperature characteristics of the respective time standards is provided. The main oscillator circuit produces a high frequency time standard signal having a first frequency rate that is determined, at least in part, by the temperature characteristic of the first time standard, which characteristic includes an inflection peak at a specific temperature. The second oscillator circuit produces a second high frequency time standard signal having a second predetermined frequency, determined, at least in part, by the temperature characteristic of the second time standard being distinct from that of the first time standard.

Abstract: An arrangement enables the frequency variation of a resonant element (an accelerating section for example) to be followed in dependence upon its temperature and the frequency of the hyperfrequency generator G feeding this resonant element Q to be controlled in dependence upon the frequency variations thereof. The arrangement comprises at least one reference cavity C associated with means for allowing the circulation of cooling fluid along the walls of said reference cavity and with heat supply for bringing it, at any instant, to the temperature of the resonant element Q, means for measuring the amplitude variation .DELTA.a of the signal corresponding to the frequency variation of said reference cavity C in terms of its temperature variation and a frequency variation system controlled by a signal proportional to the amplitude variation .DELTA.a, for modifying the operating frequency of the generator G.

Abstract: Apparatus, including an injection lock and voltage controlled oscillator, generates a signal that follows the average frequency variations and instantaneous phase variations of a repetitive non-continuous signal. The oscillator injection lock input receives the repetitive signal and its DC control input receives an error signal generated in an AFC loop which derives the difference between the oscillator output and the repetitive signal average frequency. In one particular application, the appartus is useful in a color television signal processing or reproducing system for generating a television color subcarrier signal. The apparatus is further disclosed in connection with a demodulation-remodulation type color corrector in a video reproducing system.

Abstract: An oscillator or similar device employing a frequency setting SAW element having a piezoelectric substrate and an arrangement of interdigital finger transducers mounted thereon. In one embodiment, two interdigital finger transducers provide surface acoustic wave launching and reception respectively and in another embodiment, two additional transducers form a part of a discriminator circuit. Phase detection either between the electrical connections of the launching and receiving transducers or through the discriminator arrangement generates a feedback control signal which is applied across the ends of the substrate as a stress-controlling signal in a manner to compensate for temperature and other environmental factors which otherwise change the frequency of oscillation.

Abstract: An input signal, whose frequency is to be detected, is divided and sent i two arms. One arm applies a set phase and amplitude adjustment while the other arm has a phase response that is dependent upon the frequency. Both arms are fed to a phase detector whose output is used to indicate the frequency of the input.

Abstract: A frequency synthesizer or programmable multiple frequency source which uses a voltage-controlled oscillator (VCO) responsive to an independent control variable. The VCO is also responsive to control from an error loop circuit which derives an additional control voltage as a result of comparing the VCO frequency at any time with one of the phase delay multiples of a fiber optic delay line. The independent variable used to select an overall frequency desired controls the VCO directly to an approximate frequency and the fiber optic delay line and error generating loop associated therewith operates as an automatic vernier on the VCO to bring it into phase-lock with the nearest frequency which is a multiple of the reciprocal of the fiber optic line delay time.

Abstract: Method and apparatus for comparing and/or adjusting the frequency output of a frequency source, which method and apparatus is greatly simplified, and permits adjustment within a relatively short time interval and at a precision whose known difference is less than five parts in the 10.sup.12.The rubidium-controlled oscillator employed by the major networks to produce the 3.58 MHz subcarrier signal is utilized as a standard. Offsets made available at regular intervals by the National Bureau of Standards are utilized to indicate the frequency differences between the network standards and the United States Frequency Standard (USFS).

Abstract: A digitally settable frequency generator comprises a master oscillator whose operating frequency f.sub.Q is variable between a normal value f.sub.Q " and a slightly lower value f.sub.Q ' = (1-p)f.sub.Q " with the aid of a normally disconnected tuning capacitor. The master oscillator works into a frequency divider of fixed step-down ratio m:1 (or 2m:1) to produce a reference frequency f.sub.B. A slave oscillator, generating an output frequency f.sub.A = gf.sub.B, is controlled by a phase-locking loop including a phase comparator to which the reference frequency f.sub.B is fed along with a like frequency obtained from output frequency f.sub.A with the aid of another divider having a digitally variable integral step-down ratio g:1. A fractional value i, which may range from 0 to 100%, is set with the aid of a numerical interpolation selector to determine the number n<m of cycles of operating frequency f.sub.Q within a cycle (or half-cycle) of reference frequency f.sub.

Abstract: In combination with an asynchronous detector for detecting a particular digital word within a train of signals wherein the detector samples each bit in the train a plurality of times and provides a comparison signal in response to a predetermined number of correlations between the samples and a stored word, an analog to digital converter including signal conditioning means having first and second modes of operations for converting a received analog signal to a digital signal in both modes of operation and inserting periodic error pulses in the digital signal in the first mode of operation and switch means coupled to the signal conditioning means and the detector for switching the signal conditioning means between the first and second modes of operation in response to a comparison signal from the detector.

Abstract: A stabilized frequency oscillating circuit comprises a voltage or current controlled variable frequency oscillator, a delay device receiving the output of the oscillator, an adder for adding the output of the oscillator and the delayed output of the delay device, and a detecting circuit which detects the amplitude of the output of the adder to provide a control signal which varies cyclically with changes in the oscillating frequency of the oscillator which is applied to the latter for locking the oscillating frequency of the oscillator to a predetermined or desired frequency. The oscillating circuit may further have a control circuit by which an additional control voltage or current is superimposed on the cyclically varying control signal for selecting the oscillating frequency to which the variable frequency oscillator is to be locked, or by which either the oscillator output or delayed output is phase-shifted before being applied to the adder.

Abstract: A highly stable variable frequency oscillator is disclosed which employs a ultitap surface acoustic wave device as a frequency standard. A feedback path which includes a voltage controlled switch for selecting a desired output tap drives a differential amplifier, phase detector, low pass filter, voltage controlled oscillator and phase splitter for driving the input tap of the surface acoustic wave device. Various additional feedback paths are also employed. The variable frequency signal is taken from the output of the voltage controlled oscillator.

Abstract: An unlocked detector for a digital delay lock loop employs an up-down cour which periodically accumulates the algebraic sum of the quantized positive and negative adjustments made at a preselected rate by the incremental phase modulator. Whenever this sum reaches a specified threshold value corresponding to a particular phase error, an unlocked indication is given. Arrangements utilizing the same principle are disclosed for analog loops.

Abstract: A signal detection circuit for determining synchronism and asynchronism in a phase synchronization circuit having a loop consisting of a first phase detector, a loop filter and a voltage controlled oscillator, has a second phase detector for input signals of the phase synchronization circuit and output signals of the voltage controlled oscillator. The output of the second phase detector is supplied to a low pass filter and a level judgment circuit. The level judgment circuit includes a Schmitt trigger circuit with two threshold levels due to hysteresis effect to reduce misjudgments when the input signals are low signal to noise signals.

Abstract: A surface acoustic wave oscillator comprises a surface acoustic wave delay line and amplifier. The phase difference between signals received from two transducers on the surface acoustic wave delay line is measured by a phase sensitive detector whose output is used to control a phase correction circuit. The oscillator may oscillate at a steady frequency or be frequency modulated.

Abstract: Linear accuracy of the output-signal frequency of a scanning oscillator is aintained through monitoring the location in a shift register of a pulse whose position is indicative of the frequency error from a desired scanning oscillator output-signal frequency.