1288 results about "Frequency stabilization" patented technology

A wireless spread spectrum communication system for transmitting data includes a plurality of end point transmitters and at least one receiver. The end point transmitters transmit data via a frequency hopped spread spectrum signal where the transmitting signal is sent without the benefit of frequency stabilization. The receiver is responsive to the frequency hopping spread spectrum signals and includes a correlator and a signal processor. The correlator samples at least a first portion of a preamble of the signal and correlates the portion of the preamble with a known preamble pattern to determine a probability of correlation. The signal processor applies a Fast Fourier Transform algorithm to the signal in response to the probability of correlation to track a narrowband frequency of the signal based on at least a second portion of the preamble and to decode data encoded within the signal subsequent to the preamble.

A vertical extended cavity surface emitting laser (VECSEL) includes intra-cavity frequency doubling. Conventional frequency control elements, such as etalons, are replaced with thin film interference filters or volume Bragg gratings.

Stable magnetic field measurement is enabled without collapse of polarization or fluctuation of intensity of a laser beam incident on a glass cell of an optical pumping magnetic sensor. Excitation light generated with a light source, having optimized light intensity and polarized wave, through frequency stabilization, intensity control and polarized-wave control, is introduced via a polarized wave holding optical fiber to a magnetic sensor provided in a magnetic shield, and magnetic field measurement is performed by optical pumping using magneto-optical properties of spin-polarized alkali metal. The magnetic sensor has a structure where a lens, a polarization optical device, the glass cell and a photodetector, are integrally accommodated in a non-magnetic case.

A resonant converter is provided which may be used for supplying power to the primary conductive path of an inductively coupled power transfer (ICPT) system. The converter includes a variable reactive element in the resonant circuit which may be controlled to vary the effective inductance or capacitance of the reactive element. The frequency of the converter is stabilised to a nominal value by sensing the frequency of the converter resonant circuit, comparing the sensed frequency with a nominal frequency and varying the effective inductance or capacitance of the variable reactive element to adjust the converter frequency toward the nominal frequency.

Techniques for stabilizing a laser at a selectable frequency include splitting an output beam from an electrically adjustable laser into a first beam and a second beam. The second beam is transmitted through a modulator. Then the second beam is transmitted through a transient spectral hole burning material onto a detector. The laser is electronically adjusted in response to a detector output from the detector which senses the changes in the modulated second beam after it passes through the transient spectral hole burning material. Additions here to encompass the mode-locked case?

The invention discloses a dynamic power coordination control method for a battery energy storage system. The battery energy storage system comprises a plurality of power converters which supply power to a load and are connected in parallel for operation, and is characterized in that: the power converters connected in parallel for operation are divided into two types, and a master-slave control scheme is adopted, wherein one type comprises only one power converter which adopts a constant voltage constant frequency control mode and is called a master node, and the power converters of the other type adopt a constant power mode with a slight droop characteristic, and serve as slave nodes; generally, a power converter with a high capacity is selected to be the only one master node which is specified by an upper-layer monitoring system, and all the other power converters are the slave nodes; and under a stable state condition, active power and reactive power output by the power converters which serve as the slave nodes are set by a power instruction transmitted by the monitoring system, and the output power of the power converter which serves as the master node is dynamically regulated according to a load condition. The method adopting the master-slave control scheme has the advantages that: on the premise of sufficient power capacity, both the voltage stability and frequency stability of a micro-grid system are easily achieved, anti-load disturbance capability is high, and failure recovery time is short.

A double-longitudinal-mode laser heat frequency stabilization method and a device based on the iodine frequency stabilization reference light belong to the application technical field, the invention takes the center frequency of the iodine frequency stabilization laser with a relative frequency accuracy being 10<-11> as a reference frequency, and leads the frequency of laser output by multi-double-longitudinal-mode lasers to keep one fixed difference with the reference frequency through regulating cavity length, so that the relative frequency accuracy of the double-longitudinal-mode laser is improved from 10<-7>-10<-8> to 10<-9>, the frequency consistency of multi-double-longitudinal-mode lasers is improved from 10<-7> to 10<-9>, therefore, the problems that the relative frequency accuracy of the double-longitudinal-mode laser can not exceed 10<-8> and the frequency consistency of multi-double-longitudinal-mode lasers is poor are solved.

The invention discloses a micro-grid system voltage stability control method based on robust control. The control structure of an intelligent micro-grid system is composed of a system control layer, a concentrated control layer and a local control layer, and energy optimization and voltage and frequency stability control of the micro-grid system are realized through multi-layer coordination control. According to the micro-grid system voltage stability control method based on robust control, a comprehensive load module of an induction motor is established, wherein dynamic loads are connected with static loads in parallel. On the premise that the constraint conditions of system performance and robust stability are met, a micro-grid voltage stability robust controller is designed by the adoption of a method of solving the problem of mixed sensitivity so as to improve the micro-grid voltage stability. The micro-grid system voltage stability control method based on robust control can be adapted to wide-range change of load parameters, has high robustness for the situations that due to the factors such as changes of running conditions, influences of external environment and frequency switching of the loads, perturbation is generated in model parameters of a micro-grid and uncertainty exists in the topologic part and the unmolded part and can better restrain parameter drift and noise interference, and meanwhile, the controller is simple in structure and easy to realize.

A digital cordless telecommunication system capable of maintaining the enhanced frequency stability of radio transmission signals from stationary base stations by use of a specific clock signal including either a high-precision clock or a reference clock as generated by main equipment. In this system the main equipment is provided with a high-precision oscillator that generates and issues a clock signal with increased pulse-phase accuracy, whist a respective one of the base stations is with a line interface for extraction of such high-precision clock signal from the high-precision oscillator, a reference oscillator which supplies a reference clock to a frequency synthesizer that generates a local oscillation signal, a frequency error detector operable to detect a difference or "error" in frequency between the reference clock of the reference oscillator and the high-precision clock of the line interface, and a reference oscillator controller which is responsive to receipt of the error signal from the frequency error detector for adjusting any possible frequency deviation of the reference oscillator causing the reference clock frequency of the reference oscillator to keep track of the frequency of the high-precision clock signal.

A double-longitudinal-mode laser frequency-offset-lock method and a device based on cavity length thermal regulation belong to the application technical field; the invention takes the frequency of laser output by a power balanced type double-longitudinal-mode frequency stabilization laser A as a reference frequency, and simultaneously leads the frequency of laser output by the double-longitudinal-mode laser A with n being more than or equal to B1, B2,..., Bn to keep one fixed difference with the reference frequency, thus ensuring that the laser output by the double-longitudinal-mode laser B1, B2,..., Bn has uniform frequency value, the frequency stability and frequency consistency of the double-longitudinal-mode laser can reach 10<-8>, thereby overcoming the shortcoming that the frequency consistency between frequency stabilization lasers only reaches 10<-6>-10<-7> in the traditional frequency stabilization lasers.

In various embodiments, the invention provides a discrete clock generator and / or a timing and frequency reference using an LC-oscillator topology, having a frequency controller to control and provide a stable resonant frequency, which may then be provided to other, second circuitry such as a processor or controller. Frequency stability is provided over variations in a selected parameter such as temperature and fabrication process variations. The various apparatus embodiments include a sensor adapted to provide a signal in response to at least one parameter of a plurality of parameters; and a frequency controller adapted to modify the resonant frequency in response to the second signal. In exemplary embodiments, the sensor is implemented as a current source responsive to temperature fluctuations, and the frequency controller is implemented as a plurality of controlled reactance modules which are selectively couplable to the resonator or to one or more control voltages. The controlled reactance modules may include fixed or variable capacitances or inductances, and may be binary weighted. Arrays of resistive modules are also provided, to generate one or more control voltages.

In various embodiments, the invention provides a clock generator and / or a timing and frequency reference using an LC-oscillator topology, having a frequency controller to control and provide a stable resonant frequency, which is integrated with other, second circuitry such as a processor or controller. Frequency stability is provided over variations in a selected parameter such as temperature and fabrication process variations. The various apparatus embodiments include a sensor adapted to provide a signal in response to at least one parameter of a plurality of parameters; and a frequency controller adapted to modify the resonant frequency in response to the second signal. In exemplary embodiments, the sensor is implemented as a current source responsive to temperature fluctuations, and the frequency controller is implemented as a plurality of controlled reactance modules which are selectively couplable to the resonator or to one or more control voltages. The controlled reactance modules may include fixed or variable capacitances or inductances, and may be binary weighted. Arrays of resistive modules are also provided, to generate one or more control voltages.

In various embodiments, the invention provides a clock generator and / or a timing and frequency reference using an LC-oscillator topology, having a frequency controller to control and provide a stable resonant frequency, which is integrated with other, second circuitry such as a processor or controller. Frequency stability is provided over variations in a selected parameter such as temperature and fabrication process variations. The various apparatus embodiments include a sensor adapted to provide a signal in response to at least one parameter of a plurality of parameters; and a frequency controller adapted to modify the resonant frequency in response to the second signal. In exemplary embodiments, the sensor is implemented as a current source responsive to temperature fluctuations, and the frequency controller is implemented as a plurality of controlled reactance modules which are selectively couplable to the resonator or to one or more control voltages. The controlled reactance modules may include fixed or variable capacitances or inductances, and may be binary weighted. Arrays of resistive modules are also provided, to generate one or more control voltages.

The invention discloses a frequency layering coordination control method suitable for a isolating microgrid including diesel generator and battery storage. A frequency control system comprises a central decision layer and a local decision layer, primary frequency modulation and secondary frequency modulation of the system can be realized, wherein a diesel generator in the local decision layer is taken as a main regulating unit for the primary frequency modulation; a PI (proportional-integral) controller in a dead zone of the central decision layer and distributed battery storage in the local decision layer form an auxiliary primary frequency modulation unit; and the two layers coordinate with each other to modulate the frequency once. When the frequency is stable at upper limit or lower limit of the primary frequency modulation dead zone, the secondary frequency modulation is started. The secondary frequency modulation is finished by coordination of the secondary frequency modulation module in the central decision layer and a microsource in the local decision layer; the spinning reserve or pitch peak reserve of the diesel generator is regulated by resetting active power reference value of the distributed battery storage, regulating power of the new energy, starting / stopping the diesel generator and controlling the load and so on, so as to lead the frequency of the system to recover the rated frequency. With the adoption of the frequency layering coordination control method, response characteristics of different microsources can be coordinated and utilized completely to modulate the frequency of the system, thereby simple, quick and stable control of the isolated microgrid is realized. The method has the advantages of strong robustness and flexibility, and with the adoption of the method, requirements of long-term safe and stable operation of the isolated microgrid system can be met.

The invention relates to a high-precision multi-frequency phase-synchronized laser distance measurement device and method, relates to the technical filed of laser measurement, and mainly relates to a phase laser distance measurement technology. In the invention, the problem that a device and a method capable of realizing both synchronization and stability of multiple measurement gauges are in shortage in the phase laser distance measurement technology is solved. The high-precision multi-frequency phase-synchronized laser distance measurement device comprises a dual-longitudinal-mode frequencystabilization He-Ne laser, a multi measurement gauge generation unit, a beam expanding collimating mirror group, a measuring light path and circuit unit and a control casing unit. The high-precision multi-frequency phase-synchronized laser distance measurement method specifically comprises the following steps of: 1, starting the dual-longitudinal-mode frequency stabilization He-Ne laser; 2, taking one beam of laser as a reference laser beam and the other beam as a measurement laser beam; 3, taking [(f'+f2)-(f+f1)] as the frequency of an accurate measurement gauge and taking (f1-f2) as the frequency of a coarse measurement gauge; 4, moving a measurement corner-cube prism to a target end; 5, obtaining a phase difference phi p; 6, obtaining a phase difference phi c; and 7, obtaining the distance. Thus, the method and device disclosed by the invention can be used for laser distance measurement.

This invention discloses one method and device to improve time zone signals frequency stability measurement, which comprises the following steps: reference time signals are processed through DDS technique to get stable and accurate circle signals; expending measurement frequency signals range to get better reference signals and signals to be tested at fine time measurement; using DDS unit to process measurement frequency signals; when circle sample time singles come, according to fine time measurement module minimum resolution rate to test signals to be tested with reference time signals minimum phase difference to make the meter work to fulfill frequency signal measurement.

The invention relates to a frequency control strategy for a multiple DC (Direct Current) send-out island power grid. The frequency control strategy comprises the following steps of: 1, for the multiple DC send-out island power grid of which the system frequency is risen or reduced due to a fault, firstly, starting a first defense line and utilizing a DC system frequency limiting function to control the system frequency; 2, when the frequency exceeds a frequency operated dead zone of a dynamo governor, starting another measure in the first defense line, i.e. carrying out primary frequency modulation control by the dynamo governor; 3, when the frequency exceeds a range of 49.0 to 50.6Hz, starting a second defense line, i.e. cutting off a generator or a load according to a control strategy; 4, when the frequency exceeds 50.6Hz, starting a third defense line and carrying out high-frequency cut-off protection to cut off a generating set; 5, when the frequency exceeds 51.5Hz, enabling the generator to execute the overspeed protection action and cutting off the generating set. The frequency control strategy can be used as an actual control strategy for stabilizing the frequency of a large-scale multiple DC send-out island system to be applied to production and operation of the power grid and also can be applied to emulation calculation of related research.

A droop control-based smooth switching method is provided. Output voltage amplitude and frequency are adjusted through adopting droop control, namely the balance of reactive power and active power, such that an inverter can either be in autonomous operation or be in grid-connected operation. When the state of a power grid is normal, a control unit adjusts the output voltage amplitude and frequency of the inverter; after the output voltage amplitude and frequency satisfy a requirement for grid connection, a grid-connection switch is switched off; the inverter will output proper voltage and frequency according to a droop equation based on frequency and voltage changes before and after the switching of two operation modes of a system, such that the stability of the voltage and frequency of the system can be maintained; and when an abnormal state of the power grid is detected, or an autonomous operation mode is required to be switched to, the grid-connection switch is switched off, and at the same time, because of the frequency and the voltage changes of the system, the inverter will automatically output proper reactive power and active power according to the droop equation, such that the balance of the reactive power and active power of the system can be maintained. The droop control-based smooth switching method can realize smooth switching of the autonomous operation or the grid-connected operation of the inverter through adopting the droop control.

The invention discloses a method and a device for stabilizing laser frequency and power. The method comprises the following steps of: obtaining primary diffracted light, and radiating the primary diffracted light into a photoelectric detector; detecting the intensity of the primary diffracted light; processing a detected signal; sending the processed signal to a driving source; and enabling an output signal of the driving source to act on an acoustic optical modulator. The device comprises a laser, the acoustic optical modulator, an electrooptical modulator, a polarization splitting prism, a quarter-wave plate and a Fabry-Perot interferometer. The method and the device have the advantages that reference precision and stability are greatly improved, better power stabilizing effect is realized, and frequency stabilizing effect is improved.

The invention discloses a virtual synchronous generator-based dynamic power compensation method of a diesel storage hybrid independent micro-grid. The method comprises a virtual synchronous generator control method for fixing virtual inertia and a damping parameter under the condition of steady-state operation of a system, a virtual synchronous generator control method for self-correcting the virtual inertia and the damping parameter under the condition of load disturbance on the system, and a virtual synchronous generator control method for negative inertia in a dynamic recovery process of a frequency of the system. By the virtual synchronous generator-based dynamic power compensation method, the frequency stability of a diesel storage hybrid independent micro-grid system comprising a micro-grid energy storage inverter under a steady-state condition is considered; reduction of frequency amplitude deviation of the system by the independent micro-grid system under the condition of the load disturbance is ensured; and fast recovery of the frequency of the system can also be ensured, so that the power supply quality of the system is effectively improved; and the virtual synchronous generator-based dynamic power compensation method can be widely applied to the independent micro-grid system for networking operation for the micro-grid energy storage inverter and a diesel generator set.

A compact atomic oscillator with improved frequency stability. A voltage-controlled oscillator generates an oscillation signal based on a given control voltage, and a modulator modulates it with a low-frequency signal. A phase-locked loop (PLL) upconverts the modulated oscillation signal directly to a first frequency in atomic resonance frequency band. The first frequency is an integer multiple of the oscillation signal. A frequency synthesizer produces a second frequency specified by a frequency setting unit, and a mixer combines the first and second frequencies to produce an RF signal for driving an atomic resonator. The amount of discharge lamp light passing through the atomic resonator depends on the difference between RF signal frequency and atomic resonance frequency. This quantity is measured as a resonance detection signal, and a frequency controller applies it to synchronous detection to produce a control voltage for the voltage-control oscillator.