Showing papers on "Frequency drift published in 1979"

Frequency adaptive, power-energy re-scheduler

Abstract: A frequency adaptive, power-energy re-scheduler (FAPER) that includes a frequency transducer that notes frequency or frequency deviations of an electrical system and logic means which controls and re-schedules power flow to a load unit in part on the basis of the deviations in frequency from a nominal frequency and in part on the needs to the load unit as expressed by an external sensor signal obtained from the physical system affected by the load unit

Automatic pretuning of a voltage controlled oscillator in a frequency synthesizer using successive approximation

Abstract: The automatic pretuning of a voltage controlled oscillator in a phase locked loop frequency synthesizer utilizes a successive approximation technique to rapidly bring the coarse tuning voltage of the oscillator to the desired pretuning value. A digital number stored in a digital register is converted to an analog voltage value and applied to the voltage controlled oscillator as the coarse tuning voltage. The frequency of the output signal from the oscillator is compared with a reference signal, and control logic responsive to the sense of the frequency difference between the reference signal and the oscillator output signal adjusts the value of the number stored in the digital register successively from the most significant bit to the least significant bit. A microprocessor can be used to adjust the value of the number stored in the register, as well as provide additional functions such as reverse successive approximation when the synthesizer is switched from one frequency to another frequency. The microprocessor can also be used to sweep the coarse tuning voltage of the oscillator until the output signal is within the capture range of the phase locked loop, and thereafter perform a successive approximation function to bring the coarse tuning voltage to the center of the capture range.

Laser gyroscope system

Abstract: A four-frequency laser gyroscope system having improved accuracy is constructed using a single solid block of low thermal coefficient of expansion material. A four-segment nonplanar propagation path provides a first frequency splitting. A second splitting is provided by a Faraday rotator having a thin slab of rare earth-doped glass positioned within an aperture in a permanent magnet. A narrow angle of incidence is provided for the beams of incident upon the output mirror to prevent cross coupling between beams within the output optics structure. Blocking the gaseous flow path reduces output frequency drift caused by contamininating particles.

Resistance-bridge to frequency converter with automatic offset correction

Abstract: A circuit for converting changes in a sensed physical parameter, such as resistance and resistance change as a function of pressure, temperature and the like, into a digital signal of proportional frequency. A sensor bridge, monitoring the parameter to be measured, forms a part of a feedback loop controlling a current into a resistance-capacitance integrator which is part of a controlled oscillator. The oscillator has automatic offset error correction. The frequency of the sensor-controlled is proportional to the unbalance in the sensor bridge. The converter receives power on a two-wire line from a power supply which may be located remotely therefrom, and from which power supply the sensed-parameter-established frequency is extracted for use by processing-control apparatus and the like.

Speed control circuit for phase-locked loop motor drive systems

Abstract: A phase-locked loop motor drive system includes a crystal-controlled frequency source for generating reference frequency pulses at a selectable frequency for driving the motor at a desired speed and a frequency divider coupled to the oscillator to reduce the oscillator frequency to a suitable value as a reference frequency for comparison with the frequency and phase of a signal derived from the motor. In order to provide fine adjustment of the motor speed, a speed control circuit is connected between the oscillator and the frequency divider to inhibit the passage of the oscillator pulses to the frequency divider for a selectable period immediately following an output pulse from the frequency divider when it is desired to decrease the motor speed, and inject a train of higher frequency pulses into the frequency divider while the passage of the oscillator pulses is inhibited when it is desired to increase the motor speed.

Plural frequency oscillator employing multiple fiber-optic delay line

Abstract: Stabilization of an oscillator, particularly an RF oscillator, is achieved by an arrangement employing a fiber optic delay line. The delay line has a Q defined by the relationship Q=2πfτ, where f is the oscillator operation frequency and τ is the length of the delay line. Opto/electronic and electro optic transducers are coupled between the electrical oscillator circuitry and the optical delay line for interfacing the electrical section of the RF oscillator with its optical section. This optic delay line may be configured as a single optical fiber where a single output frequency is desired, or it may be configured of a plurality of optical fibers of respectively different lengths, where plural output frequencies are to be produced.

New canonic sinusoidal oscillator with independent frequency control through a single grounded resistor

Abstract: A novel sinusoidal oscillator is presented which employs only one operational amplifier, two capacitors, and six resistors and has the facility of independent control of oscillation frequency through a single grounded resistor. The circuit may also be used as a very-low-frequency oscillator and as an economical voltage-controlled oscillator.

Frequency synthesizer tuning system for television receivers

Abstract: A television tuning system employs a frequency synthesizer system for establishing the tuning of the receiver. A programmable frequency divider counter is connected between the output of a reference oscillator and a phase comparator to which the output of the local oscillator in the tuner also is applied. The phase comparator output provides a tuning voltage for controlling the tuning of the local oscillator. A microprocessor is used to control the count of the programmable frequency divider and initially to set a count corresponding to the selected channel in a counter connected between the output of the local oscillator and the phase comparator. The AFT discriminator signal is used to sense the presence or absence of a properly tuned condition and to control the operation of the microprocessor for establishing the count in the programmable frequency divider counter. For a localized search, the microprocessor may drive the programmable frequency divider counter to a predetermined maximum count and then step back a fixed number of counts to a lower count and resume counting in the original direction; so that even if the AFT discriminator output is in an ambiguous condition, proper tuning can be achieved. However, if the AFT discriminator output produces the correct tuning direction information initially, the programmable frequency divider is adjusted step by step to the appropriate larger or smaller count that corresponds to correct tuning.

Multi band radio receiver system with phase locked loop

Abstract: A multi band radio employs frequency counters to determine a scaling factor during coarse tuning which is employed in a phase locked loop to control the frequency of a local oscillator during normal operation. Frequency counters count the frequency in the phase locked loop and in a low variable frequency generator to determine the rf frequency to which the receiver is tuned. Read only memories provide band and frequency displays with control signals based on the counted frequencies.

Frequency measuring apparatus

Abstract: An input signal frequency and the output from a local oscillator are applied to a frequency converter to derive therefrom intermediate-frequency signals of frequencies corresponding to the differences between the input signal frequency and the output frequency of the local oscillator and between the former and harmonic frequencies of the latter. The intermediate-frequency signals are amplified by an amplifier, and the output freqeuncy of the amplifier and the oscillation frequency of the local oscillator are simultaneously measured twice. From intermediate frequencies F i1 and F i2 and the local oscillation frequencies F 1 and F 2 thus measured, the following calculation is made: ##EQU1## where α is zero or a decimal. At the same time, it is detected which one of the intermediate frequencies F i1 and F i2 is larger, and from the result of this determination, the above-mentioned N, the local oscillation frequency and the intermediate frequency corresponding thereto, the input signal frequency is calculated.

Frequency stabilization circuit for a local oscillator

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.

Synthesizer type receiver

Abstract: PURPOSE: To constitute a receiver of superior frequency stability whose reception frequency is variable at random frequency intervals by frequency-dividing the output of an oscillator under the control of the 2nd PLL circuit and by performing conversion into the 2nd intermediate frequency with its output. CONSTITUTION: An arrival signal from antenna 1 is converted into the 1st intermediate frequency by frequency mixer 4 with the output of the 1st local oscillator 5 of the 1st PLL circuit 28, and it is applied to frequency mixer 8 by way of the 1st intermediate frequency amplifier. The output of oscillator 11 of the 2nd PLL circuit 29, on the other hand, is divided by M at frequency divider 10 and higher harmonics are extracted by filtering at low-pass filter 9 and then supplied to and converted by frequency mixer 8 into the 2nd intermediate frequency. Maximum frequency intervals at which the output of frequency divider 10 is variable are equalized to minimum frequency intervals at which the output of the 1st local oscillator 5 is variable and dividing ratios of dividing-ratio setting circuits 21 and 25 are brought under the coupling control of dividing-ratio arithmethic circuit 22. COPYRIGHT: (C)1981,JPO&Japio

Unit time producing system

Abstract: In an electronic timepiece, a system for producing a unit time signal with a high degree of frequency stability, composed of a low frequency oscillator, a high frequency oscillator of a high degree of frequency stability which is activated only during periodic short intervals, and means for producing a timebase signal which is an exact integral submultiple in frequency of the high frequency oscillator signal, by modifying the output signal from the low frequency oscillator on the basis of periodically recurring phase coincidence between the high and low frequency oscillator signals. Information on this phase variation is stored in digital form, and is utilized to correct the low frequency signal during periods when the high frequency oscillator is inactivated.

Frequency control for paralleled AC systems

Abstract: A frequency control utilizing a reference oscillator and a signal controlled oscillator is disclosed. The frequency control maintains the frequency of an output signal at the same frequency as the reference oscillator if there is no signal present at a frequency control input. A signal at the frequency control input causes the frequency of the output signal to be varied accordingly. The frequency control contains a feedback loop which compares the output of the signal controlled oscillator with the fixed frequency of the output of the reference frequency oscillator. The frequency control of the present invention has particular applicability as a frequency control for parallel-connected AC systems.

Crystal stabilized voltage to frequency converter with digital calibration for flowmeters

Abstract: A voltage controlled oscillator (VCO) system includes a feedback loop for maintaining the linearity, temperature stability and accuracy of the VCO. The feedback loop includes means for producing a fed-back train of pulses having an amplitude equal to a reference voltage and a duty cycle proportional to the ratio of the frequency of the output of the VCO to a reference frequency. The output frequency is thereby made proportional to the input voltage times the ratio of the reference frequency to the reference voltage.

System for transmitter frequency control in coherent ladar

Abstract: A system for ensuring that the transmitted pulse of a coherent ladar is at the correct frequency for coherent detection of received echoes. A hybrid laser transmitter has its continuous mode signal frequency swept through the stabilized frequency of a local oscillator laser. At the instant when the frequency of the transmitter is at a predetermined difference from the frequency of the local oscillator, a high powered output signal is pulsed in the hybrid laser. The resulting reflected, received signals can be mixed with the continuous local oscillator signal in a crystal mixer to produce pulses at the intermediate frequency for amplification and detection. The effect of random variation in frequency of both the local oscillator and hybrid laser is thus avoided.

Frequency modulators with compensation for variations in modulation sensitivity

Abstract: In a frequency modulation system, the frequency modulation sensitivity of an oscillator is itself a function of the carrier frequency of the oscillator. The frequency modulation sensitivity is measured and stored for particular carrier frequencies, and subsequently used to control the amplitude of the modulation signal, so that when a frequency modulation signal is fed to the oscillator, a frequency deviation is obtained which is accurately related to the amplitude of the modulation signal.

Digital channel selection and fine tuning system

Abstract: A tuning system for use in a radio frequency multi-signal receiving system, e.g., for CATV converters, utilizes a closed feedback loop digital arrangement for channel selection (local oscillator frequency control) and channel fine tuning. The system may be implemented either via discrete hardware or through the use of microprocessor controlled apparatus. In accordance with one aspect of the present invention, double heterodyne tuning apparatus automatically compensates for frequency drift in the second local oscillator.

Multifrequency control from a single crystal

Abstract: A piezo-electric crystal vibrating in several modes controls several frequencies generated by voltage controlled oscillators simultaneously. The output of each voltage controlled oscillator is fed to a summing amplifier which drives the crystal. The output of the crystal is fed to individual phase detectors; each phase detector is also supplied with the output of a voltage controlled oscillator and generates a voltage proportional to the phase difference between the voltage controlled oscillator and the crystal output for correcting the output frequency of each oscillator.

Frequency adjusting methods and systems

Abstract: A frequency synthesizing arrangement is disclosed employing a phase-locked loop. The phase detector of the phase-locked loop receives an input frequency via a divider having a division factor N, and compares this divided frequency with the frequency received from a voltage controlled oscillator via a divider having a division factor N-b. Any difference is eliminated by the control signal from the phase detector which is connected to adjust the VCO frequency. Therefore, the phase-locked loop multiplies the divided input frequency by the factor (N-b). By making b very much smaller than N, the minimum step change in output frequency is approximately F.b/N 2 (where F is the input frequency to the divider). In this way, the minimum step change in frequency can be made very small.

Slip frequency control for variable speed induction motors

Abstract: A closed-loop drive system for variable speed induction motors for maintaining a constant slip frequency, regardless of motor speed. A slip frequency oscillator generates a signal having a frequency proportional to the desired slip of the motor and a tachometer generates a signal having a frequency proportional to the actual rotational speed of the motor. The stator frequency is the sum of the rotor speed and the slip frequency during acceleration and the difference between the rotor speed and the slip frequency during braking. Exclusive OR gates are used to add the slip frequency signal either to the tachometer signal or to the stator signal, the outputs of the gates being applied to a digital phase detector. The phase detector drives a voltage controlled oscillator which provides the stator signal. The output of the voltage controlled oscillator is used to trigger the slip frequency oscillator to prevent overlap of pulses to the digital phase detector.

Digitally controlled phase lock distillator system

Abstract: A system for comparing the frequency of a voltage controlled oscillator to a stable reference oscillator to generate control signals which maintain the voltage controlled oscillator in phase lock with the reference oscillator. The circuit utilizes a digital frequency comparator to determine whether the output frequency of the voltage controlled oscillator is above or below the reference frequency. When the frequency of the oscillator is either above or below the desired value, pulses are generated which are integrated to produce a DC signal which changes the frequency of the oscillator to achieve the desired value. Additionally, a continuous electrical signal is generated when the output of the voltage controlled oscillator is in phase with the reference signal. When phase lock is achieved the output of the frequency determining circuit goes to zero and phase lock is maintained by the continuous electrical signal.

Wide range drift compensated FM signal generator

Abstract: The output frequency of a variable frequency oscillator is compared with that of a reference frequency source by means of a phase detector and the resultant error signal is integrated and applied as a negative feedback signal to the input of the oscillator whereby drift of the oscillator output frequency is minimized. Deviation, modulation index, dynamic stability and linearity are enhanced by means of a pulse generator that is synchronized with a modulating input signal supplied to the oscillator for supplying a keying signal to the phase detector during a portion of each cycle of the modulating input signal.

Local oscillator for multi-band reception having single crystal reference oscillator

Abstract: A local oscillator having a variable frequency oscillator and a carrier frequency oscillator for use in communication systems that transmit and/or receive signals on multiple frequency bands, one crystal reference oscillator; a converter circuit for mixing the outputs of at least the variable frequency oscillator and the carrier frequency oscillator to produce an output having a frequency corresponding to the receiving frequency and a phase-locked loop circuit including a plurality of voltage control oscillators corresponding to the number of receiving frequency bands; a mixing circuit for mixing the output of a predetermined one of the voltage control oscillators corresponding to a predetermined one of the frequency bands with the output of the converter circuit to produce an output of fixed frequency corresponding to the one frequency band; a programmable counter that divides the output of the mixing circuit in accordance with a frequency dividing ratio corresponding to the one frequency band; and a phase comparator for comparing the phase of the output signal from the programmable counter with that of the output from the one crystal reference oscillator to provide a control signal for the one voltage control oscillator whereby the one crystal reference oscillator may be employed with all of the voltage control oscillators.

Frequency modulation threshold extension demodulator utilizing frequency compression feedback with frequency drift correction

Abstract: In a frequency modulation detection system, the voltage controlled local oscillator is controlled by two feedback loops. One feedback loop, containing a phase detector and a resonant circuit, responds sensitively to slight lack of alignment between the phase of the intermediate frequency signal and the phase of the driven oscillations in the resonant circuit, to correct the local oscillator over an automatic frequency control circuit having a low pass characteristic. The other feedback circuit is a frequency compression loop which uses a linear discriminator circuit to demodulate the modulated intermediate frequency. The audio frequency output of this discriminator is used to cause the local oscillator to rapidly track, at intermediate frequency-offset the radio frequency input. By use of two feedback loops it is possible to use a narrow band intermediate frequency filter, thereby reducing noise, without having drift of the circuits internally create noise products.

Digital open loop programmable frequency multiplier

Abstract: A circuit arrangement for multiplying the frequency f x of an input signal by digital techniques is disclosed. A digital counter driven by a reference oscillator establishes the ratio of the reference frequency to signal frequency. The binary representation of this ratio is applied to a binary divider circuit and divided by the frequency multiplying factor M. The quotient produced is applied to program a presettable binary down-counter operating on the reference frequency f o to produce an output frequency Mf x where the components of the reference frequency are caused to cancel out.

Crystal oscillator compensated for g-sensitivity

Abstract: A crystal reference oscillator with improved g-sensitivity is realized through the use of an appropriately oriented single axis accelerometer. Components of acceleration normal to the plane of zero g-sensitivity of the oscillator are sensed by the accelerometer which returns a correction voltage to the electronic frequency control input of the oscillator. A model is developed that permits determination of accelerometer position relative to the oscillator without prior knowledge of crystal orientation.

Pulse radar transmitting oscillator

Abstract: An oscillator circuit for use in a pulsed radar transmitter includes a reference oscillator of one frequency of, a voltage controlled oscillator controlled to transmit a radio frequency at a different frequency, and a switch for connecting the two oscillators together to inject lock the voltage controlled oscillator to the frequency of the reference oscillator when no transmitting is occurring.

Means for linearizing a voltage variable capacitor controlled oscillator

Abstract: Frequency modulation of an information signal is provided by applying the signal to series connected voltage variable capacity diodes. The reactance of the diodes is coupled through a transmission line to a cavity oscillator. The varying diode reactance causes a corresponding change in the frequency of modulation of the oscillator. The improvement comprises a linearization potentiometer which couples to the diodes and provides a means to vary the effective impedance presented to the cavity oscillator such that a linear change in signal voltage applied to the diodes results in a linear change of oscillator frequency.

Common control with frequency drift compensation for a plurality of switching regulators

Abstract: A power supply system having a plurality of individual power supplies utilizes a master control to periodically compensate for errors in individual power supplies. The master control is periodically coupled to individual power supplies by multiplexing means to provide compensation signals to counter drifts and errors due to varying circuit parameters therein.