484 results about "Frequency meter" patented technology

The invention discloses a self-adaptive fault reflection method and device based on adjustable excitation frequency, and belongs to the technical field of cable fault detection and positioning. The method comprises the following steps: injecting an excitation signal which can be adjusted in a range of 1kHz-10MHz through an adjustable impedance matching network; collecting a reflected signal and calculating an SNR (f) curve; optimizing by adopting a particle swarm optimization algorithm and taking maximization of a signal-to-noise ratio as a target, and determining an optimal excitation frequency; and finally, calculating the fault position and type based on the optimal frequency. The particle swarm optimization algorithm is adopted to perform adaptive optimization on the excitation frequency, and the adjustable impedance matching network is combined to form a closed-loop adaptive detection framework of excitation-acquisition-analysis-optimization-re-excitation, so that the excitation frequency can be automatically adjusted according to a real-time detection result, and the detection accuracy is improved. And the fault detection sensitivity, the positioning precision and the energy efficiency are obviously improved.

The invention relates to the technical field of electrical fault identification and response, in particular to a relay protection fault identification and response system, which comprises a fault propagation path tracking module, a regional fault monitoring module, a misoperation cumulative effect calculation module, a protection level adjustment module and a fault response module. According to the method, based on the triggering sequence and the triggering interval time of the relay protection device, a malfunction propagation mode is extracted, cascade malfunction associated devices are screened, regional power grid fault risk scores are combined, protection level setting is optimized, the malfunction accumulation trend is calculated through malfunction triggering frequency, and high-malfunction devices are identified. The method comprises the following steps: calculating a protection level adjustment factor, optimizing a relay protection level according to a power grid state, enabling a protection strategy to adapt to different operation conditions, calculating power grid operation state parameters in combination with the adjusted protection level, analyzing stability change, optimizing a relay protection response strategy, enabling a relay protection system to have adaptive adjustment capability, and reducing the sudden fault influence range.

The invention belongs to the field of power distribution automation, and relates to a power grid equipment frequency adaptive resampling method based on a dynamic scale factor, and the method comprises the steps: carrying out the point compensation through employing a linear interpolation method when a power grid equipment detects that the number of continuous lost points is smaller than or equal to 3; selecting a voltage signal channel or a current signal channel to carry out zero crossing point detection and real-time frequency calculation; when the real-time frequency obtained through calculation deviates from the nominal frequency, the power grid equipment introduces a dynamic scale factor for resampling, sampling points are increased when the real-time frequency is higher than the nominal frequency, and sampling points are reduced when the real-time frequency is lower than the nominal frequency; writing data obtained by resampling into a calculation annular cache region of the power grid equipment; and performing FFT calculation on the data in the calculation annular cache region to obtain power grid parameters. The sampling interval of the data acquisition unit is dynamically adjusted by increasing or reducing the sampling points, so that the sampling time sequence and the actual signal period are synchronized, the sampling frequency and the real-time frequency are adaptively matched, and the sampling distortion problem under the power grid frequency fluctuation is solved.

The invention discloses a deployment system for measuring multi-object vibration by using compressed sensing and a signal reconstruction method. The invention relates to an object vibration information acquisition and frequency period calculation system and method based on an RFID technology. The system aims at efficiently collecting vibration data of a plurality of objects through the RFID reader-writer and accurately processing and analyzing the vibration data. The system comprises an RFID vibration information acquisition module which is responsible for acquiring a unique identification EPC label, phase data and a timestamp of an object and storing the data in a CSV format; the data preprocessing module is used for cleaning collected data, deleting repeated timestamps and classifying the data; the measurement matrix generation module is used for constructing a signal measurement matrix so as to facilitate subsequent processing; the compressed sensing signal reconstruction module performs sparse representation and reconstruction on the vibration signal through a La sso regression algorithm, Fourier transform and other technologies, and recovers an original vibration signal of the object; and finally, the vibration period and frequency calculation module extracts the period characteristics of the signals through self-correlation analysis, and calculates the vibration frequency of the object. Through the system, the vibration states of multiple objects can be monitored and analyzed in real time, the system is widely applied to the fields of industrial monitoring, structural health monitoring and the like, and the precision and efficiency of object vibration detection are improved.

The invention relates to the technical field of variable-frequency series resonance voltage withstanding tests, and particularly discloses a variable-frequency series resonance voltage withstanding test system and a variable-frequency series resonance voltage withstanding test device. Comprising a theoretical resonant frequency calculation module, an output frequency information acquisition module, a test resonant frequency evaluation module, a voltage withstanding test information acquisition module, a voltage withstanding performance stability analysis module and a power cable insulation performance evaluation module. According to the method, the resonant frequency accuracy of a series resonant circuit in a complete resonant state is deeply analyzed, and the voltage-withstanding stability and the insulation performance of the power cable are analyzed by combining the voltage condition, the leakage current condition, the temperature condition and the partial discharge condition of the power cable in a voltage-withstanding test; and meanwhile, the coverage of voltage-withstanding stability evaluation of the power cable is improved, so that the persuasion of the insulation performance of the power cable to unqualified evaluation is improved, and a more targeted basis is provided for maintenance and repair of the power cable.

The invention relates to the field of pulse signal generation, and discloses an integer frequency signal generation circuit and method for a microprocessor, and the circuit comprises a flipping register, a frequency division register, a counter, a frequency signal flipping module, an integer frequency calculation unit, and a time delay unit. The integer frequency calculation unit is used for calculating the delay series of the fractional part of the frequency division value when the enable signal 1 is valid, and sending the delay series to the delay unit; and the delay unit is used for carrying out delay less than one clock period on the frequency signal output by the frequency signal overturning module according to the delay series sent by the integer frequency calculation unit, and outputting an integer frequency signal. According to the integer frequency signal output circuit disclosed by the invention, the frequency division value and the delay series of the frequency division register are automatically changed through the integer calculation module and the delay series calculation module, and the delay series controls the one-out-of-256 selector to be used for selecting the frequency signal output of the corresponding delay module in the delay unit, so that the generation of the integer frequency signal is realized.

The invention relates to a miniaturized closed-loop FID scalar atom magnetometer and an implementation method thereof, and belongs to the field of atom magnetic measurement. According to the method, the closed-loop working mode of the FID magnetometer is realized by utilizing a self-made electronics system, the modulation frequency of pumping light is corrected in real time, so that the magnetometer still keeps high sensitivity under a large magnetic field change rate, and the performance restriction between the dynamic range and the sensitivity of an open-loop FID magnetometer is broken through. The interaction between the self-made frequency meter and the time sequence control system is the core component of the closed loop of the magnetometer system. The device can measure a magnetic field with a large change rate at a high speed, is high in sensitivity and accuracy, and plays an important role in field magnetic measurement application.

The embodiment of the invention discloses an aero-engine rotating speed measuring device which is characterized by comprising a tachogenerator module, a hardware conditioning module, a high-speed A / D conversion module, a data picking and buffering module, a digital signal processing module, a rotating speed measuring module, a power supply module, an operation control module and a communication module which are connected in sequence. The tachogenerator module converts an acquired engine rotating speed signal into a sine-wave-like alternating-current voltage signal of which the frequency and the amplitude are positively correlated with the rotating speed. The hardware conditioning module is used for conditioning the sine-like signal with a relatively wide amplitude range into a signal meeting the amplitude range requirement of the high-speed A / D conversion module; the high-speed A / D conversion module performs high-speed sampling on the conditioned sinusoidal-like signal and converts the conditioned sinusoidal-like signal into a digital signal; the data picking and buffering module is used for picking and buffering the digital signals subjected to A / D conversion; the digital signal processing module is used for converting the digital signal into a digital square wave signal; the rotating speed measuring module is used for monitoring the frequency of the digital square wave signal and calculating the rotating speed of the engine through the frequency; and the communication module is used for uploading the engine rotating speed measurement result to the flight control computer. The technical scheme of the invention solves the problem.

A printed circuit board (PCB) test system and method including temperature chamber including at least one slot to accommodate at least one PCB test coupon, input bus connected to inputs of the at least one slot, and output bus connected to outputs of the at least one slot, wherein temperature chamber is configured to apply a temperature to the at least one PCB test coupon; signal generator including output bus connected to the input bus of the at least one slot, frequency meter comprising an input bus connected to the output bus of the at least one slot and an output bus, and a comparator connected to the output bus of the signal generator and the output bus of the frequency meter for comparing corresponding outputs of the signal generator and the frequency meter.

The invention provides a CPT atomic clock magnetic field coil constant calibration system and method.The CPT atomic clock magnetic field coil constant calibration system comprises a CPT atomic clock, a frequency measurement module and an upper computer, the upper computer is used for setting the number of times of measurement, calculating a third analog signal in each time of measurement according to a first digital signal in each time of measurement, and sending the third analog signal to the CPT atomic clock; calculating the actual clock transition frequency during each measurement according to the frequency division number of the phase-locked loop circuit and the frequency of the clock signal during each measurement, calculating the external magnetic field during each measurement according to the actual clock transition frequency during each measurement, and finally performing linear fitting according to the external magnetic field during multiple measurements and the third analog signal to obtain a third analog signal; and obtaining a magnetic field coil constant. The invention provides a CPT atomic clock magnetic field coil constant calibration system and method. The system and method are used for solving the problems that a magnetic field coil in a CPT atomic clock is small and cannot be measured, current distribution calculation is complex due to the fact that magnetic shielding is applied, and the actual winding condition of the coil cannot be accurately simulated during simulation.

The invention relates to an OWS earphone active noise reduction method, electronic equipment and a readable storage medium. The method comprises the following steps: acquiring a noise signal through a microphone; analyzing the noise signal, and when the volume of the noise signal is greater than a preset volume threshold value, generating a noise reduction sound wave opposite to the phase of the noise signal through an electroacoustic transducer to eliminate noise; analyzing the noise signal to determine an environmental scene; when the OWS earphone is in a commuting scene, determining the phase and frequency of a noise reduction sound wave according to a noise signal collected by the microphone; calculating a noise reduction evaluation index in the commuting scene, and adjusting the phase and frequency of a noise reduction sound wave according to the noise reduction evaluation index to maintain an optimal noise reduction effect; different noise reduction modes are set according to common application scenes of the earphone, feedback can be made according to noise reduction requirements of different application scenes, the use experience of a user is not affected while the noise reduction effect is generated, and meanwhile the optimal noise reduction effect is kept through the noise reduction evaluation index.

The invention relates to the technical field of anti-seismic performance detection, in particular to an anti-seismic performance detection method and system for an assembled steel-wood composite structure, and the method comprises the steps: arranging a multidirectional acoustic emission sensor in a steel-wood structure node area, applying simulated seismic vibration, and synchronously collecting acoustic emission signals; the method comprises the following steps: preprocessing collected acoustic emission signals, dividing the acoustic emission signals into signals corresponding to microcracks and contact slippage, respectively calculating an energy attenuation rate and a phase offset, and constructing a matrix; micro-impact is applied to the steel-wood node through an electromagnetic excitation device, a response signal is collected, resonant frequency is extracted, the drift distance between the resonant frequency and a reference value is calculated, and the severity of interface damage is determined according to the value of the drift distance; the damage correlation index calculation takes the characteristic value of the interface wave propagation characteristic matrix and the resonance frequency drift distance as input, the damage correlation index is calculated through the correlation coefficient, and the damage grade is divided according to the correlation coefficient. And differential characterization of different damage types is realized through the interface wave propagation characteristic matrix.

The invention discloses a fan frequency control method and device, electronic equipment and a computer medium, and belongs to the technical field of automatic incineration. According to the specific scheme, the method comprises the steps of obtaining a parameter sequence value of a control parameter of the automatic combustion control system in a historical period, a current flow value of main steam flow, a flow set value of the main steam flow, a real-time value of steam pocket pressure, a hearth material layer pressure difference value and a control variable sequence value in the historical period; calculating a flow predicted value of the main steam flow; calculating flow deviation; calculating the frequency of an intermediate fan; the steam drum fan frequency is calculated; the flow fan frequency is obtained; calculating a primary frequency given value; and the primary frequency set value is dynamically corrected, and the target primary fan frequency of the primary fan is obtained and adopted to control the primary fan. The response speed of the automatic combustion control system can be effectively improved, so that the control of the frequency of the extension set can be closer to the actual production condition.

The invention relates to the field of load control, in particular to a non-fixed load accurate removal method based on load control fairness and effectiveness consideration. Comprising the following steps: acquiring the frequency of a power grid system, calculating the frequency change rate, judging whether to send a'preparation for load shedding 'instruction to all substations by monitoring the frequency of the power grid system and the frequency change rate, entering a load shedding amount calculation stage, and calculating the load amount needing to be cut off in each region through a dynamic weighted load precise cutting algorithm, calculating a total load shedding amount; based on the load capacity needing to be cut off in each area, the substation optimizes the cut-off combination of the load lines in the areas, after optimization is completed, the substation executes cut-off, and the master station monitors the frequency and the frequency change rate of the power grid system after cut-off and judges whether a locking condition is met or not so as to stop further cut-off. The technical problems that power grid frequency monitoring mostly depends on low-sampling-rate equipment, the rapidly-changing frequency dynamic state is difficult to capture, and instability detection lags or misjudgments are caused are solved.

The embodiment of the invention relates to the technical field of transformer fault detection, and discloses a transformer winding fault detection method and system based on frequency response and a medium, and the method comprises the steps: determining the equivalent inductance and equivalent capacitance of a transformer winding; and calculating a first-order grounding coefficient of driving point admittance by using the peak frequency and the valley frequency when the neutral point is grounded, and calculating a first-order open-circuit coefficient by using the peak frequency and the valley frequency when the neutral point is open-circuit. A first difference function is constructed through the equivalent inductance, the scaling rate and the first-order grounding coefficient, and a second difference function is constructed through the equivalent capacitance and the first-order open circuit coefficient. And fault detection of the transformer winding is carried out according to a comparison condition between fluctuation of the first difference function and the second difference function and a preset threshold value, and early sensitive detection is realized.

The invention provides a short bolt axial stress detection method and device based on electromagnetic ultrasonic resonance, and relates to the technical field of industrial fastener stress detection. The method comprises the following steps: determining a preset period and frequency of an excitation signal according to material characteristics of a to-be-measured short bolt, and calibrating resonant frequency and stress to obtain a calibration curve; classifying the lengths of the short bolts to be measured to obtain bolts with known original lengths and in-service bolts with unknown original lengths; based on the determined preset period and frequency, first-order resonant frequency corresponding to the bolt with the known original length is obtained through an electromagnetic ultrasonic transducer and a single-wave resonance method; based on the determined preset period and frequency, first-order resonant frequency corresponding to the in-service bolt with the unknown original length is obtained through an electromagnetic ultrasonic transducer and a double-wave resonance method; and calculating the axial stress of the corresponding short bolt to be measured according to the calibration curve and the first-order resonant frequency. The problems that in the prior art, the energy conversion efficiency is low, and the short bolt detection effect is poor are solved.

The invention relates to the technical field of photovoltaic support monitoring, and discloses a photovoltaic support displacement safety monitoring method. The method comprises the steps that sensors are installed at different nodes of a photovoltaic support based on a stay wire displacement monitoring system, and horizontal displacement and vertical displacement are collected in real time; correcting the displacement data through multi-dimensional data fusion in combination with environmental factors; and calculating the vibration frequency of the bracket, monitoring the frequency change in real time, and generating a bracket health assessment report and an early warning signal. In the prior art, accurate monitoring of support displacement is difficult to realize under a complex environment condition, and especially under the condition of non-uniform support stress or foundation settlement, accurate displacement monitoring and early warning cannot be provided. According to the invention, through multi-node sensor data acquisition, environmental factor correction and dynamic vibration frequency calculation, accurate monitoring and early warning of the displacement of the photovoltaic support are realized, and the operation safety and reliability of a photovoltaic system are improved.

The invention provides a non-contact measuring device and method for medium pressure in a pipeline based on an ultrasonic surface wave array, and the device comprises an ultrasonic surface wave array transmitting module, an ultrasonic surface wave receiving module, a signal amplification circuit, a high-speed signal collection card, a drive circuit, and an industrial control computer. Respectively sending driving instructions to the driving circuit when the medium pressure in the test pipeline is zero and the test pipeline is in a working state; after the amplified ultrasonic surface wave signals are received, extracting frequency signals including a zero-pressure state ultrasonic surface wave array frequency f0 and a working state ultrasonic surface wave array frequency f, calculating to obtain an ultrasonic surface wave array frequency difference value, and calculating a pressure indicating value through a pressure calculation formula; based on the ultrasonic surface wave array, the pressure of the medium in the pipeline is inverted by measuring the frequency of the ultrasonic surface wave, high-precision non-contact measurement of the pressure of the medium in the pipeline can be realized, and the sensor belongs to a novel mechanical sensor.

The invention discloses a grid-connected inverter control method and system for a triangular hysteresis primary frequency modulation dead zone. Dead zone boundary frequency change values-fdbINV and fdbINV are set; setting a hysteresis boundary frequency change value-fhdbINV and a hysteresis boundary frequency change value-fhdbINV; calculating a droop curve slope kHDINV in a hysteresis loop based on the dead zone boundary frequency change value-fdbINV, the fdbINV and the hysteresis loop boundary frequency change value-fhdbINV; sampling the frequency fg of the power grid system; calculating a difference value delta f between the power grid system frequency fg and the power grid system rated frequency fn; and performing differential processing on the difference value delta f to obtain # imgabs0 #, and determining the power variation of the inverter and the new energy field station participating in primary frequency modulation according to the difference value delta f and # imgabs1 #, thereby realizing the adjustment of the power grid frequency, reducing the steady-state frequency deviation, and simultaneously preventing the oscillation among different control schemes near a dead zone boundary and a hysteresis boundary.

The invention discloses an LLCL filter design method, and relates to the technical field of power electronics. The method comprises the following steps: acquiring an initial filter capacitance, an initial inverter side filter inductance, a power grid side filter inductance and a target frequency; calculating filtering branch inductance based on the filtering capacitance and the target frequency; calculating a positive harmonic peak frequency based on the filter capacitor, the inverter side filter inductor, the power grid side filter inductor and the filter branch inductor; calculating damping resistance, damping inductance and damping capacitance based on the positive harmonic peak frequency, the filter capacitance, the resonant frequency value constraint, the first value range constraint and the second value range constraint of the quality factor; and when the target parameter does not meet the grid-connected current harmonic standard, updating the filter capacitor and / or the inverter side filter inductance, and skipping to the step of calculating the filter branch inductance based on the filter capacitor and the target frequency so as to carry out iteration until the grid-connected current harmonic standard is met. According to the embodiment of the invention, the design optimization of the parameter value of the filter element in the LLCL filter is realized.

The invention discloses a ship signal adaptive time-frequency analysis method based on instantaneous frequency direction self-adjustment. The ship signal adaptive time-frequency analysis method comprises the steps of collecting ship signals to be subjected to time-frequency analysis and performing short-time Fourier transform; estimating the instantaneous frequency of the ship signal based on short-time Fourier transform time-frequency distribution in combination with time-frequency narrow-band features; calculating the instantaneous frequency and the optimal window length after smoothing; segmenting the smoothed instantaneous frequency in time, calculating time-frequency domain direction pre-guidance of each time period, and constructing a Chirp atomic direction over-complete dictionary; segmenting the ship signal in time, and calculating the matching direction of the ship signal in each time period so as to calculate and improve Chirplet transformation time-frequency distribution; and calculating the optimal short-time Fourier transform in combination with the optimal window length, and correcting and improving Chirplet transform time-frequency distribution. According to the method, the robustness of short-time Fourier transform and the anisotropy of improved Chirplet transform are utilized at the same time, and time-frequency distribution with high robustness and high time-frequency resolution is obtained.

The invention relates to a square wave generation method and system based on a DDS signal transmitter, and belongs to the technical field of digital electronic signal synthesis. The method comprises the following steps: calculating a digital analog signal sampling frequency based on a square wave output frequency set by a user, and obtaining a digital fundamental frequency phase signal according to a phase-locked loop precision range; mapping the digital fundamental frequency phase signal into a sinusoidal amplitude signal according to a digital phase accumulation mechanism to obtain a digital-analog conversion clock, binarizing the sinusoidal amplitude signal, and outputting a square wave output period; dividing a square wave output period into a low level region and a high level region according to the precision range of the phase-locked loop, reading a square wave output frequency set by a user through a random storage address, and outputting a non-offset phase-locked square wave; and constructing an error accumulation self-checking architecture to calculate a frequency control word, and when detecting that the frequency control word has a decimal discarding error, recalculating the frequency control word.

The invention relates to a verification method and system for a mutual inductor calibrator based on accurate frequency tracking. The method comprises the following steps: sampling output signals of a standard mutual inductor and a mutual inductor to be tested to obtain original signals; sequentially performing high-pass and low-pass digital filtering on the original signal to obtain a filtered signal; performing accurate frequency calculation on the filtering signal by adopting a mode of combining zero crossing point detection and a similar triangle interpolation method, and if an absolute value of a difference value between a current fundamental frequency obtained by calculation and a fundamental frequency measured last time is greater than a set value, updating a hardware sampling interval until the absolute value is smaller than the set value; and discrete Fourier transform calculation is carried out on the filtering signals of the standard mutual inductor and the mutual inductor to be detected respectively, fundamental wave amplitudes and fundamental wave phases of the corresponding signals are obtained, and a ratio difference and an angular difference are calculated to serve as verification results of the mutual inductor calibrator. According to the invention, spectrum leakage and a fence effect in the fundamental wave extraction process can be eliminated, and the verification precision of the angular difference and the ratio error of the mutual inductor calibrator is improved.

The invention relates to the technical field of electronic measurement and sensing, and discloses a capacitance monitoring method and system based on a sweep frequency resonance point, and the method comprises the steps: carrying out the coarse sweeping in an initial frequency range, obtaining an impedance spectrum, and recognizing a coarse resonance interval; carrying out fine scanning in the interval and calculating an accurate resonant frequency by adopting a quadratic interpolation method; calculating a capacitance value in combination with the mapping table; and dynamically adjusting the frequency sweeping window of the next period based on the historical resonant frequency. The system comprises an excitation signal generation unit, an impedance response acquisition unit, a coarse / fine scanning control unit, a resonant frequency calculation unit, a capacitance resolving unit and a dynamic frequency window updating unit, and integrates a temperature compensation and anomaly detection mechanism. Through the two-stage frequency sweeping and self-adaptive frequency window strategy, the monitoring period is shortened to 1 / 5 or below of that of a traditional method while it is guaranteed that the resonant frequency measurement precision is superior to 0.01 Hz, and the real-time performance, stability and environmental adaptability are remarkably improved.

The invention relates to a non-contact conductivity measuring device which comprises an RLC (Radio Link Control) circuit, a signal generator, an oscilloscope and a calculation module, wherein the RLC circuit is formed by connecting a resistor, a capacitor and an inductor in series; the inductor consists of a solenoid and a conductor rod arranged in the center of the solenoid; the signal generator serves as an input voltage source of the RLC circuit; the oscilloscope is used for monitoring voltage signals at two ends of the capacitor and voltage signals at two ends of the input voltage source; the calculation module is used for obtaining the resonant frequency of the RLC circuit according to the ratio of the voltage signals at the two ends of the capacitor to the voltage signals at the two ends of the input voltage source; and the controller is also used for calculating the conductivity of the to-be-measured conductor rod according to the outer radius of the to-be-measured conductor rod, the outer radius of the solenoid, the length of the solenoid, the number of close winding turns of the solenoid, the capacitance value of the capacitor and the resonance frequency. It can be understood that by means of the technical scheme, the conductivity of the conductor rod can be measured in a non-contact mode, and the testing accuracy is high.

The invention provides a temperature excursion compensation method and a starting characteristic compensation method of a current frequency conversion circuit. The temperature excursion compensation method comprises the following steps: determining a full temperature interval of working of the current frequency conversion circuit; dividing the full-temperature interval into a plurality of sub-temperature intervals according to a set step length; in each sub-temperature interval, performing low-order polynomial fitting on the acquisition temperature and the frequency count value of the current frequency conversion circuit, establishing a temperature factor temperature drift compensation model, and obtaining a polynomial temperature compensation parameter of each sub-temperature interval; the current temperature of the current frequency conversion circuit is collected, the sub-temperature interval where the current temperature is located is determined, and a corresponding fitting scale factor is obtained; and calculating the compensated scale factor. According to the invention, through temperature interval division and low-order nonlinear fitting, compensation in a scale factor full-temperature range is realized, and the problem that an existing compensation algorithm is restricted by FPGA resources and time sequences is solved.

The invention discloses a large-aperture grating scanning etching period error suppression method based on frequency domain analysis. The method comprises the following steps: S1, forming a path function # imgabs0 #; s2, the removal amount distribution # imgabs 1 # is calculated; s3, performing power spectrum density analysis to obtain a spectrum amplitude; s4, extracting a frequency # imgabs2 #; s5, the scanning line spacing # imgabs4 # under the frequency # imgabs3 # is calculated; s6, a new scanning path # imgabs5 # is formed; s7, processing the large-aperture grating sample piece; and S8, judging whether the large-aperture grating sample piece meets the requirement or not, if so, ending and exiting, otherwise, extracting the frequency spectrum amplitude of the frequency distribution of which the error is higher than the drawing error in the frequency spectrum, and skipping to execute the step S4. The invention aims to solve the problems that the existing large-aperture scanning etching process is too low in efficiency and easy to generate sputtering pollution, and the processing efficiency and the processing quality of the large-aperture optical element are improved.

The invention discloses a frequency measurement method, system and device and a computer readable storage medium, and belongs to the technical field of electricians. Acquiring a sampling value, and judging whether the sampling value is invalid or not based on the absolute value of the sampling value; determining a first frequency value based on the sampling value and the sampling frequency; determining an amplitude and a phase of a vector value of the signal based on the sampling value; determining a second frequency value according to the phase change; determining a frequency based on the first frequency value and the second frequency value; according to the frequency measurement method, system and device and the computer readable storage medium, a low-value locking technology, an extreme value anti-shake technology, a sampling zero crossing point anti-shake technology and a hysteresis frequency calculation technology are adopted, and sampling point frequency measurement and vector frequency measurement are organically combined, so that the frequency measurement precision when the signal frequency fluctuates in a large range under different working conditions is ensured; and the problem that the frequency measurement error is large when the signal frequency fluctuates in a large range is solved.

The invention relates to the technical field of signal frequency measurement, in particular to a low-frequency-band fixed square wave frequency high-precision measurement method based on a kernel clock, which is suitable for the field of embedded systems and digital signal processing, is mainly used for low-frequency and fixed-frequency-band high-precision frequency measurement, and is not a frequency meter method specially used for measuring frequency. The method is suitable for measuring the fixed output frequency in a test system and the like. According to the method, a kernel clock of an embedded system (such as an STM32 single-chip microcomputer) is mainly utilized, a time constant is calibrated by measuring the count value of the duration of high and low levels of a fixed time window, and therefore the square wave frequency is obtained through calculation.

The invention relates to a fault monitoring method and a fault monitoring system. The fault monitoring method comprises the steps that sound signals in a cab and one or more corresponding vibration signals of one or more monitoring positions in a power system are collected in real time; calculating a frequency response function between the sound signal and each vibration signal and obtaining a peak point frequency corresponding to a peak point of each frequency response function; calculating a coherent characteristic function between each vibration signal and the sound signal and obtaining an amplitude corresponding to a peak point frequency of each frequency response function; judging whether the amplitude corresponding to the peak point frequency of each frequency response function is greater than a preset threshold value or not; and when the amplitude corresponding to the peak point frequency of the one or more frequency response functions is greater than a predetermined threshold, determining that a fault occurs at the monitoring position of the vibration signal corresponding to the one or more frequency response functions. The fault monitoring method and the fault monitoring system have improved performance.