9results about How to "High frequency resolution" patented technology

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 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 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.