20results about How to "High frequency resolution" patented technology

The invention discloses a crop disease remote sensing monitoring and early warning system based on time sequence spectral information analysis, and relates to the technical field of agricultural disease and insect pest monitoring. Computer drawing software is utilized to divide a corn planting field in equal proportion, and sensors are deployed to monitor the growth environment change in each grid in real time and generate microenvironment data information; the method comprises the following steps: calculating a microenvironment difference index Xbd according to microenvironment data, identifying a microenvironment difference aggregation area and sending a risk analysis instruction, after receiving the risk analysis instruction, capturing related spectral data information of the microenvironment difference aggregation area by using an unmanned aerial vehicle and a multispectral sensor, and constructing a multispectral fluctuation coefficient Xgp by analyzing related spectral data, and comparing the calculated rust disease risk assessment index Zpg with a preset threshold W in combination with the microenvironment difference index Xbd and the trained risk assessment model, and obtaining corresponding grade early warning according to the rust disease risk degree.

The invention discloses a multi-scale adaptive time sequence InSAR (Interferometric Synthetic Aperture Radar) earth surface deformation extraction method, and relates to the field of remote sensing signal processing. The method comprises the following steps of: constructing an unwrapped time sequence InSAR phase simulation data set, performing pixel-by-pixel time sequence empirical mode decomposition on a time domain, obtaining a time sequence intrinsic mode function at the same pixel position, and constructing a FastICA wavelet enhancement denoising algorithm on a space domain: performing two-dimensional multi-stage wavelet decomposition on the intrinsic mode function of each dimension by taking a power spectrum entropy as a cut-off condition, the method comprises the following steps of: acquiring a wavelet approximation coefficient of each level and a detail coefficient, performing noise reduction and dimension reduction processing and reconstruction on the wavelet approximation coefficient and the detail coefficient of each level, and finally performing wavelet reconstruction on the updated wavelet coefficient to obtain a processed time sequence InSAR phase simulation data set. The method provided by the invention is based on data self-driving, self-adaptive decomposition is carried out on phase signals from two scales of time and space, earth surface deformation related signals can be effectively captured, other phase signals can be separated and explained, and a scientific theoretical basis is provided for high-precision earth surface deformation monitoring.

The invention belongs to the related technical field of fuel cells, and particularly relates to a fuel cell impedance spectroscopy rapid measurement system and method, the system is divided into an excitation current injection part, a data acquisition part and an upper computer, the upper computer adopts a DIBS signal with an excellent peak value inhibition capability and a flexible amplitude-frequency design capability as test excitation, and the test excitation part is connected with the data acquisition part; an electronic load is used as an excitation source. The upper computer can control the electronic load to generate a current excitation waveform used for impedance testing based on a DIBS signal, the electronic load injects excitation current into output current of a tested galvanic pile, the upper computer can also read sampling data of the data acquisition part, fast Fourier transform is carried out on the acquired excitation current and response voltage data, and the impedance of the tested galvanic pile is tested. And obtaining an electrochemical impedance spectrum. According to the method, the impedance measurement efficiency is improved, the hardware structure is simple, the method has a good field application prospect, a measured object can be expanded to other electrochemical systems including an electrolytic tank, and the method has good expansibility.

The invention relates to the technical field of composite material structure monitoring, in particular to a composite material structure damage identification method based on acoustic emission wavelet packet energy characteristics, and the method comprises the steps: S1, obtaining acoustic emission signal data of a composite material, and carrying out the preprocessing; s2, performing wavelet packet decomposition on the denoised composite material acoustic emission signal data by using a wavelet basis function and discrete wavelet inverse transformation; s3, acquiring the processed acoustic emission signal data of the composite material, and extracting the characteristic energy of each piece of acoustic emission signal data; and S4, performing clustering analysis by using a clustering method to complete damage identification of the composite material structure. According to the method, the acoustic emission signal is used as an analysis basis, wavelet transform and k-means clustering analysis are used for accurately realizing structural damage identification and judgment of the composite material, dynamic continuous monitoring can be realized, the method is not influenced by structural complexity, and the method has wide applicability and is suitable for various composite materials.

The invention discloses an asynchronous motor rotor broken bar fault detection method and system based on a second derivative, and the method comprises the following steps: S1, obtaining a stator current sampling data sequence # imgabs0 # of any phase of an asynchronous motor, the # imgabs1 # being an nth current signal; s2, carrying out fundamental frequency suppression on the stator current sampling data sequence # imgabs2 by using a second derivative, and constructing an edge frequency function sequence # imgabs3 #, wherein # imgabs4 # is the nth edge frequency function; s3, carrying out fast Fourier transform on the side frequency function sequence # imgabs5 # to extract a side frequency characteristic frequency spectrum; and S4, judging whether the asynchronous motor has a rotor broken bar fault or not according to the side frequency characteristic spectrum. The invention aims to simplify signal acquisition required by fault detection and accurately extract the side frequency characteristic frequency spectrum reflecting the rotor broken bar fault so as to accurately diagnose the rotor broken bar fault of the asynchronous motor.

The invention discloses a decimal frequency multiplication delay phase-locked loop based on a sigma-delta modulator, and the decimal frequency multiplication delay phase-locked loop is characterized in that a logic selection signal generation module provides a logic selection signal sel to control the opening and closing of a voltage-controlled oscillator (VCO) loop so as to control the periodic switching of the decimal frequency multiplication delay phase-locked loop between a Fractional-N PLL mode and a DLL mode; a Fractional-N PLL mode is periodically switched to a DLL mode, so that a clean reference clock rising edge is periodically introduced, and the rising edge of an output clock is replaced by the clean reference clock rising edge, so that the jitter of the output clock is reduced, and meanwhile, the frequency resolution of the output clock is improved; and fractional frequency multiplication is realized by introducing a programmable frequency divider based on a sigma-delta modulator. Furthermore, the logic selection signal generation module provided by the invention has a logic self-recovery function, and can solve the problem that normal locking cannot be realized in a decimal frequency multiplication process.

The invention discloses a high-precision frequency measurement method based on sparse Fourier transform, which comprises the following steps of: issuing normal and reverse reflection parameters, rearranging the frequency spectrum of a sampled measured signal in an FPGA (Field Programmable Gate Array), and performing window function filtering and down-sampling FFT (Fast Fourier Transform) on the rearranged sequence to obtain frequency spectrum data; and then high-energy frequency points are removed, and Hash mapping and voting are carried out on the remaining frequency points to obtain high-precision frequency information.

A kind of operating condition under rotating electric machine inherent frequency calculation method discloses a kind of operating condition under rotating electric machine inherent frequency acquisition method, belong to motor structure modal parameter online identification technical field.Method includes: in stator tooth portion uniform distribution N≥4 one-way vibration sensor;Motor is under load and vibration signal is synchronously collected;Signal zero-phase band-pass filtering;The correlation function of reference point and response point is calculated, and complex modal modeling is complex exponential series;Through single-sided mutual power spectrum transformation and multiple starting time sampling matrix equation is constructed, coefficient vector is obtained by SVD solution;Root is sought by coefficient and constructs characteristic polynomial, mapping obtains system continuous pole, and then simultaneously output inherent frequency and damping ratio.The whole process does not need to stop, does not need to add excitation, noise resistance is strong, frequency identification error is less than 1%, provides modal data under real boundary condition for motor NVH optimization and structural modification.

The invention provides a fault arc identification method and system based on a wavelet neural network, and relates to the technical field of fault arc identification, and the method comprises the steps of signal collection, signal processing, first modeling, first training, fault identification and the like. The system comprises a signal acquisition module, a signal processing module, a first modeling module, a first training module and a fault identification module, historical current signals and fault type labels when fault arcs occur are adopted to train a wavelet neural network model, and the accuracy of fault arc identification is improved.

The invention discloses a high-speed sampling data real-time extraction method based on a parallel digital filter, and the method comprises the steps: collecting a measured signal through a collection system of a mixed-domain oscilloscope, obtaining a plurality of parallel signals, achieving the high-magnification real-time extraction filtering through a parallel CIC filter and a cascaded parallel half-band filter, obtaining serial data, and carrying out the real-time extraction of the serial data through the parallel CIC filter and the cascaded parallel half-band filter. And finally, performing serial extraction on the serial data to obtain output data, so that the frequency resolution of the spectral analysis function of the oscilloscope can be remarkably improved under the condition that the FFT length is not increased.

The invention discloses a user side hybrid energy storage dynamic optimization configuration method based on load frequency domain decoupling, and the method comprises the steps: measuring and calculating the annual growth rate of the power demands of a user based on an industrial user historical load curve data set, and constructing a typical weekly load curve of the future power demands of the user; a typical weekly load curve is decomposed into a high-frequency component and a low-frequency component by adopting an FMD-SET frequency domain decoupling algorithm, a parallel optimization model of hybrid energy storage is solved based on a decomposition result, and the maximum annual average net benefit of the hybrid energy storage system in the commissioning stage is taken as an optimization target. The physical operation constraint and the residual value evaluation of the hybrid energy storage system are comprehensively considered to obtain a dynamic configuration strategy, and the hybrid energy storage configuration scale suggestion and the optimal operation year setting are provided for the distribution and storage user in combination with the operation age limit of the hybrid energy storage. According to the invention, the hybrid energy storage system is configured for the industrial user under the background of two-part electricity price, and the demand cost saving of the distribution and storage user is realized by controlling the charging and discharging of the hybrid energy storage system.

The present application relates to a kind of vibration velocity demodulation systems of laser doppler vibrometer, the laser doppler vibrometer includes laser vibration measurement and laser ranging two modes, the probe of laser vibration measurement mode is converted into beat frequency electric signal after the frequency shift laser interference signal collected and exports, including high-precision heterodyne conditioning circuit, the down-conversion module with multiplier, high-speed ADC circuit and high-speed acquisition and demodulation module, its down-conversion module includes analog multiplier, first switch, second switch and the measurement channel of different down-conversion frequency suitable for low vibration speed, the first input end of analog multiplier is connected after the intermediate frequency signal processed by high-precision heterodyne conditioning circuit, other end is connected with second switch.This application simultaneously provides the vibration velocity demodulation method for realizing the vibration velocity demodulation system of the described.

The invention provides an interface electron excitation spectrum generation method based on time domain and frequency lamination scanning. The method can be applied to the technical field of nonlinear optics and interface microstructures. The interface electron excitation spectrum generation method based on time domain and frequency laminated scanning comprises the steps that in response to an interface electron excitation spectrum generation request, a first laser pulse and a second laser pulse are obtained, the first laser pulse is used for resonance excitation of a sample, and the second laser pulse is used for non-resonance excitation of the sample; generating N electron sum frequency spectrums according to the first laser pulse and the second laser pulse, N being an integer greater than or equal to 1; and carrying out iterative processing on the N electron sum frequency spectrums to obtain an interface electron excitation spectrum.

The utility model discloses a frequency modulation matching circuit and electronic equipment, and relates to the technical field of radio frequency power supplies. Wherein the output end of the system-on-chip circuit is connected with the input end of the digital frequency synthesis circuit; the output end of the digital frequency synthesis circuit is connected with the input end of the signal processing circuit; the output end of the signal processing circuit is connected with the input end of the impedance matching circuit; the first output end of the impedance matching circuit is connected with a load; the input end of the sampling circuit is connected with the second output end of the impedance matching circuit, and the output end of the sampling circuit is connected with the input end of the system-on-chip circuit. Therefore, the load is monitored in real time, the parameters of the impedance matching circuit are dynamically adjusted, the energy transmission efficiency is improved, the digital frequency synthesis technology is adopted, microsecond-level frequency switching can be achieved, the high-frequency frequency modulation requirement is met, high-frequency resolution is provided, and the precision and stability of radio-frequency signals are ensured.

The invention discloses a transient electric energy quality detection method for wide-area protection of a power grid. The method comprises the following steps: acquiring a fault signal containing a fundamental wave, a harmonic wave, an inter-harmonic wave and an attenuation direct current component; performing frequency spectrum estimation to obtain an estimated value of a fuzzy attenuation direct-current component, establishing an exponential function model to iteratively calculate a reconstructed attenuation direct-current component, solving a least square problem, taking the reconstructed attenuation direct-current component with the minimum error with the fuzzy attenuation direct-current component as final estimation, and removing the reconstructed attenuation direct-current component from a fault signal; a Taylor Fourier multi-frequency model is reconstructed for a fault signal without an attenuation direct current component to change the frequency resolution, then a dynamic phasor estimation problem is converted into a compressed sensing solving problem, and finally an improved sparsity self-adaptive matching pursuit algorithm is used for solving to obtain estimated values of phasor, frequency and frequency change rate. According to the method, the attenuation direct current component can be quickly estimated, and accurate voltage and current phasors can be calculated within an extremely short time window after a fault occurs.

The utility model discloses a three-phase program-controlled alternating current power source, which relates to the field of three-phase program-controlled alternating current power sources and comprises a digital DSP (digital signal processor) controller + large-scale FPGA (field programmable gate array) module, a three-phase alternating current power output module, a three-phase remembered sine wave generating circuit, a touch screen, a liquid crystal display module, a low-pass filter A, a low-pass filter B and a low-pass filter C, and the touch screen and the liquid crystal display module are connected with the digital DSP controller and the large-scale FPGA module. According to the utility model, the three-phase power source adopts a DSP + FPGA technology, a large-scale FPGA with powerful and flexible functions, an internal and external phase-locked closed-loop control technology, a high-speed and high-precision D / A and a high-fidelity power amplifier to form a new-generation high-precision standard power source, the frequency stability is high, the continuity is good, the precision of output voltage and current can reach 0.01 level, and a single-phase 0-380V, three-phase three-wire, high-precision and high-precision standard power source can be provided. And the three-phase four-wire alternating current voltage is 0-380V.

The utility model discloses a frequency hopping frequency source module based on DDS relates to microwave radio communication technical field, including crystal oscillator, power divider and frequency mixer, and power divider and frequency mixer are connected in parallel through first branch and second branch, and first branch includes FPGA chip, PLL chip, DDS chip and first filter who connects in order series connection, and FPGA chip and power divider first output electric connection, and first filter and frequency mixer first input electric connection, and the second output of FPGA chip and the frequency control input of DDS chip electric connection. The utility model discloses the hardware construction under relevant layout, still makes it have the advantage that the output frequency coverage is wide under the original already having the advantage that the frequency switching speed is fast, and the frequency resolution is high.

The application discloses a kind of continuous segmented secondary identification multi-frequency signal fast frequency measurement method, can realize the frequency fast and accurate measurement of wideband multi-frequency signal.First, according to signal frequency range, select appropriate resolution, after resampling, the original sampling signal is carried out primary FFT transformation, obtains the approximate range of signal frequency distribution;Then according to the resolution, the entire signal band is divided into uniform multiple, and the corresponding band-pass digital filter is designed for each section.The result after primary FFT is mapped on segmented band, the frequency band where signal frequency is located is selected, and after filtering processing, complex modulation is carried out to refine spectrum analysis, so as to complete the accurate measurement of wideband multi-frequency signal frequency.The application selects the frequency band where signal is located on the basis of primary FFT, and further refines secondary identification, can reduce the time consumption of embedded device for full-band signal scanning, improve the frequency resolution of signal analysis, realize the fast and accurate measurement of frequency.

This invention discloses a fully digitally controlled programmable Ti:sapphire femtosecond oscillator carrier envelope offset frequency locking device, comprising an avalanche photodetector, a power divider, a first RF conditioning circuit, a second RF conditioning circuit, a frequency and phase discrimination circuit, a programmable proportional circuit, a programmable integral circuit, a programmable bias circuit, an inverting summation circuit, a programmable limiting circuit, an anti-saturation integral circuit, an output buffer circuit, a main control circuit, and a host computer. This invention enables the carrier envelope offset frequency to be locked to the repetition frequency. Employing a fully digitally controlled programmable PI circuit, combined with innovative anti-saturation integral and output limiting functions, it offers advantages such as low latency, high precision, high stability, and high security.

This invention belongs to the field of hypersonic aerodynamics and discloses a method for predicting hypersonic boundary layer transition based on the numerical solution of the frequency domain Navier-Stokes equations. This method, through the assumption of small perturbations, linearly decomposes the hypersonic flow field into a steady flow field and a perturbed flow field. It eliminates the time differential terms in the time-domain Navier-Stokes equations using complex decomposition, transforming the time-domain Navier-Stokes equations into linear algebraic equations in complex space, thereby simplifying the solution and analysis of the time-domain Navier-Stokes equations. Specifically, it includes three stages: preprocessing, solver, and post-processing. The iterative solution of the frequency-domain Navier-Stokes equations in the solver is the core, including spatial discretization of the frequency-domain Navier-Stokes equations, iterative progression, implementation of boundary conditions, parallel data exchange, convergence judgment, and result output. The hypersonic boundary layer transition prediction method based on the numerical solution of the frequency-domain Navier-Stokes equations of this invention can balance computational efficiency and accuracy, and has practical engineering value.