453 results about "Frequency curve" patented technology

A system, apparatus, and method for determining the distance between two objects using an indirect propagation delay measurement is disclosed. A frequency hopping scheme (such as the Bluetooth.TM. technology) is used to measure the relative phase offset of the received signal between the various frequencies. For a given distance between the objects, the phase offset vs. frequency curve is a straight line with the slope dependent upon the measured distance. After the phase of the received signals is detected, the data is plotted on a curve and the slope is calculated. A wireless slave device remains phase locked with another device in a half-duplex communication mode by employing a low-drift phase locked loop employing a voltage controlled crystal oscillator. The phase locked loop further employs a mechanism that provides immunity from transitory phase slip at a time when the loop is opened.

In order to characterize the optical characteristics of a device, a source of light having a variable frequency with a polarization state which varies linearly with frequency is provided as an input to the device under test. The input light is also passed through a known reference path and is added to the light output from the device under test in a beam combiner. The combined light for the frequencies of interest is split into two orthogonal polarizations which are then detected in a spectral acquisition apparatus and supplied to a microprocessor. The spectral measurements are digitized and curve-fitted to provide optical power versus optical frequency curves. Fourier transforms of each of the curves are calculated by the microprocessor. From the Fourier transforms, the four arrays of constants are calculated for the Jones matrix characterizing the device under test.

A system, apparatus, and method for determining the distance between two objects using an indirect propagation delay measurement is disclosed. A frequency hopping scheme (such as the Bluetooth™ technology) is used to measure the relative phase offset of the received signal between the various frequencies. For a given distance between the objects, the phase offset vs. frequency curve is a straight line with the slope dependent upon the measured distance. After the phase of the received signals is detected, the data is plotted on a curve and the slope is calculated.

The invention relates to a method for precisely calibrating the arrival moment of initial wave head of traveling wave in transmission line faults by utilizing Hilbert-Huang transformation (HHT). The method comprises the following steps that: HHT transformation is carried out to faulty traveling wave data; EMD decomposition is carried out first, and IMF1 component intensively embodies the high frequency information of raw data and completely self-adapts to the time scale of the raw data; the IMF1 component is taken as an investigation object; an order difference curve of the IMF1 component is evaluated, and Hilbert transformation is carried out to the order difference curve so as to obtain an instantaneous frequency curve of the IMF1 component; the advantages of two curves are combined to seek an extreme point, and the extreme point is compared with the raw data to obtain the precise calibration for the arrival moment of the head of a traveling wave, and error is controlled to be less than one sampling point. In a strong-noise environment, IMF2 or IMF3 is selected, and the precise calibration for the arrival moment of the head of the traveling wave can be achieved as well according to the method. All the other mathematical methods cannot achieve the precision of the method of the invention. Principle analysis, simulation data and engineering data verification show that the method is precise to calibrate the arrival moment of the initial wave head of the traveling wave in transmission line faults.

The invention relates to system and method for detecting the transformer winding state by using constant-current sweep frequency power source excitation. A measurement and control analysis module controls sweep frequency power source and applies output constant-current sweep frequency excitation signals by an exciting transformer at a high-voltage side of the transformer to be detected; a vibration sensor measures vibration response signals of a transformer winding to be detected at different excitation frequencies; a vibration signal collector collects and preprocesses the signals measured by the vibration sensor; and the measurement and control analysis nodule carries out spectrum analysis to the received and processed vibration response signal data, displays and records a resonant frequency curve of the transformer winding on a frequency domain, compares with the resonant frequency curve previously measured and recorded as well as the vibration frequency curve of a transformer three-phase coil, and judges the state of the transformer winding to obtain the measuring result. The invention can effectively and sensitively detect the states of looseness or deformation of the transformer winding for prompt repair or replacement so as to avoid a fault of abrupt short circuit of the transformer caused by damage of the winding structure.

The invention relates to a failure diagnostic method for the dynamic stable state of power transformers. In the failure diagnostic method, the deformation condition of power transformer windings is analyzed by combining a frequency response process and an impedance process, the power transformers which have the same types and different serial numbers, the same windings with different phases and indexes of the correlation degree of frequency curves of the dynamic stable state are obtained by the frequency response process. The failure diagnostic method comprises the following steps of: analyzing the dynamic stable state of the power transformers according to related coefficients by synthesizing the advantages of the synthesize technology and the impedance process; when exceeding a permissible value, judging the related coefficients by the impedance process; and when numerical values of parameters also exceed the permissible value, determining that the failure of the dynamic stable state of the power transformers occurs.

The invention relates to the technical field of insulation detection for high voltage equipment, in particular to an insulation detection method for a high voltage bushing based on frequency domain dielectric spectroscopy. The method comprises the step that a frequency domain dielectric spectroscopy based test is adopted to detect insulation of the bushing. With the adoption of the method, an influence of a Garton effect on measuring of tan delta at low voltage is avoided; a real tan delta frequency curve of the bushing at 0.001-1000Hz and at the low voltage is acquired and used for judging an insulation state of the bushing; and compared with the traditional bushing adopting a single 50Hz frequency point tan delta to judge the insulation state of the bushing, the judgment accuracy is improved. The test and a measuring device of the method are simple in structure and easy to operate, and the difficulty that the test and the device are difficult to operate when the measuring of the tan delta of the bushing is conducted at 0.001-1000Hz and at high voltage is solved.

The invention discloses a method for quantitatively recognizing an oil deposit dominant flow channel adopting a zero dimension comparison plate. The method includes the following steps: firstly collecting geological parameters and fluid parameters of an oil field to draw a parameter distribution cumulative frequency curve and obtain corresponding distribution intervals and distribution characteristics; according to the parameter distribution characteristics of a target oil deposit, calculating a water drive development dynamic through the combination with corresponding figure conceptual models; finding out the water absorption parameters and liquid production parameters of layers with the maximum and minimum water absorption capability and liquid production capability for zero dimension treatment through the statistics of conceptual model results; drawing a zero dimension parameter distribution plate, and dividing a dominant channel developing space through the cluster analysis method and obtaining a quantitative plate; and performing the single-well zero dimension parameter treatment, and judging the developing condition of the dominant flow channel through the zero dimension comparison plate. According to the invention, the analysis data source is wide, the cost is low, the spend time is short, personnel at an ore yard can use the method conveniently, the individual judgment on each injection and production well in the oil deposit is realized, the quantitative judging standard is given, and the specific developing layer of the dominant flow channel can be confirmed.

The invention discloses a method for measuring atomic transverse relaxation time based on an electron resonance phase frequency analysis. In a strong-background magnetic field with almost neglected residual magnetization in a magnetic shielding barrel, a swept-frequency signal that has a bandwidth covering a resonance curve and has an amplitude enabling the resonance curve to have a clear curve under low polarizability is applied in a horizontal direction; an optical swing angle signal of a magnetometer is detected and a spectral analysis is carried out on an outputted signal in a polar coordinate system to obtain a phase frequency response function of the magnetometer; the phase frequency response function is fitted to a corresponding theoretical phase frequency curve of the magnetometer to obtain atomic spinning transverse relaxation time. Because the phase angle is a result obtained by quotient processing of a spinning transverse component, the influence of common coefficient fluctuation is suppressed, so that the phase frequency signal expression is more stable by being compared with amplitude-frequency signal expression. Besides, the theoretical phase frequency curve is not affected by the magnetic induction intensity of the transverse magnetic field and the atomic spinning longitudinal relaxation time, so that complexity of data processing can be reduced. Moreover, a lorenz curve widening risk caused by the transverse magnetic field can be eliminated.

The invention provides a measurement and analysis system of the voltage and frequency and its analysis method. The invention can be applied in the fields of the detection, data acquisition and analysis, and the frequency conversion technology. The device can measure the voltage signal and the frequency signal, and the precision can reach as high as 10<-6>. The invention provides a calculation and analysis method of the linearity of the voltage-frequency curve Alpha out, the ratio of the voltage and frequency Kout and the base point of the voltage and frequency V50Hz, coordinates with the drawing and analysis method of the voltage-time, the frequency-time and the voltage-frequency curve, to provide the effective auxiliary analysis method for the operation condition of the variable frequency equipment, thereby realizing the function of low cost, high precise, wide-range measurement on the voltage and frequency and intelligent analysis function of the measurement results.

The invention discloses a precession target micro-Doppler extracting method based on instant frequency modulation rate estimation. The precession target micro-Doppler extracting method based on instant frequency modulation rate estimation comprises the steps that (1) an equivalent scattering point model of a spatial precession conical target is established, echo signals of the conical target are received by a radar, echo sequences are obtained from the echo signals by using the equivalent scattering point model; (2) frequency modulation rates of the echo sequences are estimated with a relaxation demodulation line frequency modulation method; (3) the frequency modulation rates of the echo sequences are processed through a random sampling consistency algorithm, and P frequency modulation rate curves are obtained; (4) integral operation is carried out on the P frequency modulation rate curves respectively, and P instant micro-Doppler frequency estimation curves are obtained. According to the precession target micro-Doppler extracting method based on instant frequency modulation, high estimation accuracy can be obtained under the situation of the lower signal to noise ratio. The precession target micro-Doppler extracting method based on instant frequency modulation can be applied to analysis of the micro-Doppler frequency of the spatial precession conical target.

The invention belongs to the field of flood control safety design of reservoirs, and relates to a method of determining downstream design flood of cascade reservoirs. The method comprises the following steps that by the adoption of the Copula function, multi-dimensional simultaneous distribution of the section flood volume and the regional flood volume of the reservoirs is constructed, the explicit expression of a conditional probability function is deduced, the frequency curve of the conditional probability is dispersed, and according to the principle of probability combination discrete summation, the design value and the corresponding probability of the annular maximum peak discharge of downstream sections are determined after flood regulation is conducted through the cascade reservoirs. The method can overcome the defects of traditional determination technologies of the design flood of the cascade reservoirs, and provides more comprehensive reference information for cascade planning and development of drainage basins.

The invention discloses a synchronous compression transformation order analysis method for rolling bearing fault diagnosis. According to the method, firstly, SST is utilized to analyze a variable-speed vibration signal of a bearing to obtain time-frequency distribution of the vibration signal; secondly, an instantaneous frequency ridge of frequency conversion is extracted and subjected to high-order polynomial fitting, a fitted instantaneous frequency curve is obtained, and phase discrimination time marks are solved according to the fitted instantaneous frequency curve; thirdly, equal-angle resampling is performed on the original vibration signal to obtain an angular domain signal; and fourthly, Hilbert envelope demodulation is performed on the angular domain signal, an envelope order spectrum of the angular domain signal is solved, whether the rolling bearing has a fault or not and the fault type are judged by analyzing the envelope order spectrum, a diagnosis result is given, maintenance suggestions are proposed, and therefore normal running of a metro vehicle is guaranteed. Through the synchronous compression transformation order analysis method, instantaneous frequency conversion information contained in the vibration signal can be precisely extracted, order tracking is realized, a specific hardware device is not needed, the installing process is greatly simplified, and thefault monitoring cost is lowered.

The disclosed device includes core control module, excitation module and data acquisition and control module. The data acquisition and control module includes vibration sensor, charge amplifier and data acquisition unit connected to each other through circuits. The excitation module includes constant current source in frequency conversion and excitation transformer. Through analyzing change of natural resonance frequency curve of transformer winding, the disclosed device detects loosening status of winding, providing very high detection sensitivity.

The invention discloses a security monitoring method based on an air conditioner. The security monitoring method comprises the steps of: using an image collection device on the air conditioner to monitor that whether moving people exists in a room; when monitoring that the moving people exists in the room, collecting indoor images according to a preset frequency curve; extracting facial features in the collected images to obtain the facial features corresponding to the collected images, and matching the obtained facial features with preset facial features; and when the obtained facial features are failed to be matched with the preset facial features, outputting alarm information. The invention also discloses the air conditioner. According to the security monitoring method based on the air conditioner, the figure of the moving people is accurately captured, more favorable insurance is provided for extraction and recognition of the facial features of the moving people, and effective monitoring in the room is achieved.

The embodiment of the invention provides a temperature compensation method and a crystal oscillator. The crystal oscillator comprises a crystal oscillation circuit unit, a temperature sensor unit, an oscillation control unit, a relative temperature calculating unit and a temperature compensation unit. The temperature sensor unit is used for measuring the measurement temperature of the crystal oscillation circuit unit; the relative temperature calculating unit is used for obtaining the temperature difference value between the measurement temperature and a reference temperature; the temperature compensation unit is used for obtaining a temperature compensation value corresponding to the temperature difference value from a temperature frequency curve; and the oscillation control unit is used for generating a frequency control signal according to tracking frequency of a communication AFC (Automatic Frequency Control) device and the temperature compensation value so as to control the frequency of the crystal oscillation circuit unit to work on the tracking frequency. In the embodiment of the invention, the temperature compensation value is determined by obtaining the temperature difference value between the measurement temperature and the reference temperature according to the temperature difference value and the coefficients of the temperature frequency curve, so that better temperature compensation results are obtained with relatively low cost.

The invention discloses a phase-locked loop frequency synthesizer which is characterized in that the phase-locked loop frequency synthesizer comprises a phase-frequency phase discriminator, a charge pump, a low-pass filter, a broadband differential LC oscillator provided with a capacitor array of a control switch, a multimode frequency divider and a controller which is used for a self-adapting frequency regulating curve; the analogue signal control end of the broadband differential LC oscillator is connected with an output signal Vctrl of the low-pass filter, and the digital signal control end thereof is connected with the output end of the controller. The phase-locked loop frequency synthesizer further comprises a 3-order full digital Sigma-delta modulator provided with a three-bit quantizer. The phase-locked loop frequency synthesizer can realize fractional frequency division, and the output frequency signals thereof can be continuously changed at a wide range, and the precision of the frequency spectrum is high.

A voltage controlled oscillator (VCO) conducts current on two paths through parallel inductors and parallel cross-coupled metal-oxide-semiconductor transistors. A pair of varactors are connected in series on a third path extending from a node between one inductor and one transistor to a node between the other inductor and the other transistor. The oscillation frequency is controlled by a voltage applied to a node between the two varactors on the third path. Each varactor is structured as a metal-oxide-semiconductor transistor with interconnected source and drain electrodes, a gate electrode, a body region below the gate electrode, and a body terminal region extending beyond the gate electrode. An adjustment voltage applied to the body terminal region shifts the voltage-capacitance curve of the varactor and the voltage-frequency curve of the VCO without changing the shapes of these curves, providing a simple way to adjust the VCO to meet application requirements.

The invention discloses an electrical prospecting method and a measuring device. The method comprises the following steps of: transmitting a current waveform serving as an excitation signal with pseudo-random code characteristics to the underground through a transmitter; receiving a voltage signal generated by the excitation signal through a receiver; mathematically processing to obtain a pulse transition function; obtaining an amplitude-frequency curve and a phase frequency curve in a corresponding frequency range through fast Fourier transform; obtaining an amplitude value and a phase value of each frequency point; and obtaining apparent resistivity and phase parameters with geophysical meaning through the parameters. The device comprises a transmitter consisting of a computer, a programmable logic device, a transmitter clock synchronization circuit, a logic sequence generator, a self-sampling processing circuit, a direct current power supply, a drive and protection circuit, a self-sampling filtering circuit and a power supply electrode AB, and a receiver consisting of a filtering and protecting circuit, an amplifying and analog / digital sampling circuit, a programmable logic device and a computer. The device has good anti-interference performance, can perform effective measurement at low power and can be matched with a plurality of sets of equipment to perform measurement simultaneously.

The invention relates to a DC fault arc detection method. The method is characterized by comprising the following steps of 1, sampling, filtering and conducting the fast Fourier transformation on an input current of a high-frequency power electronic converter to obtain an amplitude-versus-frequency curve for the high-frequency components of the current; 2, selecting at least one frequency band containing a switching frequency or a multiple frequency from the amplitude-versus-frequency curve, and calculating the peak value D1 of the magnitude of the curve and the mean value D2 of the magnitude of the curve within the selected frequency band. Based on the change of the distance between the peak value D1 and the mean value D2, whether an arc is generated or not can be judged. If the mean value D2 gets closer to the peak value D1, the arc is judged to be generated. Otherwise, no arc is generated. According to the novel DC fault arc detection method, based on the own characteristics of the converter, noise signals are generated by the high-frequency components of the direct current at the frequency multiplication points of the switching frequency of the converter. By utilizing the noise signals, the arc spectrum of an arc fault can be analyzed and calculated. In this way, whether the arc fault occurs or not can be detected.

The invention relates to a frequency safety online monitoring and assessment method of a power system, which comprises the following steps: (1) setting a transient frequency safety binary table (fcr, fcr); (2) acquiring real-time frequency data of all monitoring points of the power system from an energy management system (EMS); (3) filtering the dynamic frequency data of all the monitoring points on the basis of a moving average method; (4) primarily analyzing the frequency data; (5) analyzing every group of dynamic frequency data, and calculating a frequency safety margin index according to the relationship between a frequency curve and the binary table (fcr, fcr) by the following three conditions: (1) tb = 0; (2) 0 < tb < tcr; and (3) tb > tcr, wherein tb is time that the frequency curve in an observation window deviates from fcr, and a frequency safety quantitative assessment method which takes frequency deviation cumulative effect is applied to the frequency safety margin calculation; and (6) comprehensively analyzing the frequency safety margin calculation results of all the monitoring points, taking the minimum margin value as a system frequency safety margin, and feeding back the system frequency safety margin to the energy management system for information display.

The invention discloses an unsmooth dynamic compensation method for an ultralow-frequency horizontal vibration table guide rail. The unsmooth dynamic compensation method comprises the following steps: measuring unsmooth dynamic characteristics of the ultralow-frequency horizontal vibration table guide rail and output uori t of a calibrated acceleration sensor in real time by taking a horizontal direction as reference; constructing a guide rail unsmoothness dynamic compensation system, and removing a gravitational acceleration component in the output of the calibrated sensor generated by pitching of a sliding table from the original output of the calibrated sensor in real time in the vibration calibration process; calibrating a calibrated acceleration sensor by adopting the compensated output ucomt of the calibrated sensor, calculating to obtain a compensated amplitude-frequency curve, and finishing vibration calibration of the calibrated sensor. The unsmooth dynamic compensation method has the advantages that the calibration result deviation of the acceleration sensor with zero frequency response caused by guide rail unsmoothness based on the ultralow-frequency horizontal vibration table can be compensated in real time in the vibration calibration process, so that the precision of ultralow-frequency vibration calibration is improved.

The invention relates to a phase angle margin compensation-based system impedance active control method of a grid-connected inverter. Because the changing impedance exists in a power grid, a dynamic interaction influence exists between the grid-connected inverter and the power grid and thus the grid-connected current waveform quality is influenced, so that the weakening of the impedance interaction influence is crucial to improvement of the grid-connected current quality. According to the invention, the impedance active control method is characterized in that real-time grid impedance information is obtained in real time and thus a phase angle margin at an inverter output impedance amplitude-frequency curve intersection point frequency is solved; a voltage feedforward control method is employed and a phase angle margin of the inverter impedance at the impedance intersection point frequency is compensated in real time; operation is carried out on a voltage feedforward link output and a current ring PI result so as to obtain an SPWM control signal. According to the invention, because the active impedance control method with the phase angle margin compensation function is used, the harmonic resonance generated by the dynamic interaction influence between the inverter and the power grid near the impedance intersection point frequency can be effectively suppressed, so that the rid-connected current waveform quality of the inverter is improved and the grid-connected stability is enhanced.

The invention provides a CPU+GPU heterogeneous parallel computing based natural frequency characteristic analysis method for a turbomachinery blade. The method comprises the steps of firstly, establishing a finite element model according to a three-dimensional model and material parameters of a to-be-analyzed turbomachinery blade, and performing pre-stress analysis on the blade; secondly, performing blade grid data preprocessing, simultaneously calculating a rigidity matrix and a mass matrix of each unit in a CPU and a GPU, and assembling the rigidity matrix and the mass matrix into total rigidity and mass matrixes; setting constraint conditions of the blade and a rim, wherein the setting process comprises constraint of rigid and elastic displacement of a boundary, contact coupling of a blade root and the rim or contact coupling of connecting pieces and correction of the total rigidity matrix; thirdly, extracting generalized eigenvalues and eigenvectors of the total rigidity and mass matrixes by using a CPU+GPU heterogeneous parallel algorithm; fourthly, converting the eigenvalues and eigenvectors into a frequency and a vibration mode of the blade, and performing output; and finally, judging a vibration type of a natural vibration mode, and drawing frequency curve distribution, a vibration safety graph or a Campbell chart of the blade according to the vibration type.

The invention discloses a method for predicting residual service life of an asphalt pavement according to fatigue-modulus comprehensive performance of a core sample. The method comprises the following steps: boring a core and sampling at a typical disease position of an asphalt pavement; determining resilience modulus of the core sample under the action of dynamic loading; determining a deformation-cyclic loading frequency curve for a core sample fatigue test; modeling to predict the residual service life of the asphalt pavement. The method further comprises a step of combining with a temperature factor to obtain the practical life of the pavement, and further comprises a step of combining with a traffic factor to obtain the practical life of the pavement. According to the method provided by the invention, the viscoelastic property of an asphalt mixture is comprehensively considered; due to the dynamic loading action, the practical stress situation of the pavement is stimulated, the modulus of different positions is analyzed and compared, the residual service of the pavement is described by a fatigue curve, quantitative residual life prediction is provided for maintenance of an asphalt concrete pavement, and randomness of the selection on pavement maintenance time for a long time can be overcome.

The invention discloses an audio identification method and system based on empirical mode decomposition. The method comprises the following steps: A, inputting original audio signals, sampling the original audio signals, then obtaining frequency spectrum data by successively performing denoising preprocessing, Hamming windowing and Fourier transformation processing, and then obtaining a sound spectrogram by successive connection with each frame of the frequency spectrum data; B, obtaining an energy maximum point of each frequency range of the sound spectrogram, and generating a time-frequency curve through successive connection with the energy maximum point of each frequency range; C, obtaining multiple intrinsic mode functions by performing the empirical mode decomposition on the generated time-frequency curve; and D, through the obtained multiple intrinsic mode functions, through combination with the corresponding frequency ranges and time frames, generating and outputting multiple feature values used for representing the original audio signals. According to the invention, change trend information of audio features can be fully integrated with generation of the feature values, and the generated feature values can more completely represent the audio signals.

The invention discloses a method for re-sampling vibration signals of a rotary machine in angular domains on the basis of instantaneous frequency estimation, and relates to a method for diagnosing and managing mechanical faults. The method includes acquiring the vibration signals of the rotary machine, performing down-sampling on the vibration signals in time domains, computing instantaneous frequencies of the vibration signals, dividing instantaneous frequency sequences, fitting an instantaneous frequency curve, computing sampling moment sequences of the signals in the angular domains and computing amplitude sequences corresponding to sampling moments of the signals in the angular domains; computing the amplitude sequences corresponding to the sampling moments of the signals in the angular domains by a Lagrange interpolation algorithm, solving corresponding amplitude sequences A(t) corresponding to original signals at re-sampling moments and finally acquiring re-sampled signals R(t) of the vibration signals in the angular domains. The method has the advantages that an extra tachometer for extracting rotation speed information is omitted, the rotation information of a rotary shaft can be directly acquired from the vibration signals, the analytical precision is high, the cost of hardware is low, and the method is unlimited by environments and specifically has a significance in technological transformation for existing equipment of enterprises.

The invention discloses a meshing frequency and spectrum correction technology based wind power gear box order tracking method. The meshing frequency and spectrum correction technology based wind power gear box order tracking method comprises performing discrete sampling on vibration acceleration signals on the surface of a box body of a fan planet gear box to obtain a non-stationary time domain sequence xn (t); adding a hanning window w (t) to intercept a section of xn (t) and performing FFT (Fast Fourier Transformation) to obtain a power spectrum G (f); performing frequency correction on the meshing frequency fm of a gear box high-speed shaft in the G (f) by a four-point energy centrobaric correction method to obtain an instantaneous meshing frequency which is expressed by the formula; moving window functions in turn and extracting the formula by the energy centrobaric method repeatedly to obtain a meshing frequency curve which is expressed by the formula; obtaining a high-speed shaft rotating frequency curve according to the relation between the meshing frequency and the rotating frequency, wherein the high-speed shaft rotating frequency curve is expressed by the formula; combining with the formula to performing equal-angle resampling on the xn (t) to obtain a smooth angle domain sequence theta n (t); performing correction on the order time and the amplitude by a window length moving method and the energy centrobaric method to obtain an order tracking curves Oi (t). The meshing frequency and spectrum correction technology based wind power gear box order tracking method is good in generality, high in anti-noise performance and accurate and reliable and the problems that a method for measuring the fan rotating speed through a tachometer is difficult in installation, high in cost, poor in accuracy and the like can be avoided.

The invention provides a frequency mixing nonlinear ultrasonic detection method for structure microcracks based on bispectrum analysis, and belongs to the detection field of nondestructive examination. The method comprises the steps of firstly, obtaining an amplitude-versus-frequency curve of an excited probe and an excited receiving probe through frequency sweep experiments, and determining probe excitation frequency or range according to the amplitude-versus-frequency curve; then, carrying out different lateral excitation frequency mixing mode experiments, tracking difference frequency and sum frequency signals, and determining an optimal frequency of the excitation signals according to amplitude-versus-frequency response characteristics of the difference frequency and sum frequency signals; performing bispectrum analysis on the time domain signals at the optimal frequency, and determining whether structure microcracks exist in a test piece or not according to whether mixing components appear in the bispectra or not; and scanning the length direction of a test piece and tracking the difference frequency and sum frequency signals by changing time delay of the excitation signals, and determining the positions of the structure microcracks according to the amplitude-versus-frequency response characteristics of the difference frequency and sum frequency signals. Influences on experimental results caused by nonlinearity of an experiment apparatus can be prevented by employing two probes to excite the signals; and the positions of the structure microcracks can be identified by making the two signals encountered through controlling the delay time of the excited signals.

The invention relates to the technical field of sound boxes, in particular to a sound debugging method and device based on an amplitude-frequency response curve; the method comprises the following steps: acquiring an audio signal acquired by a microphone, generating a measurement amplitude-frequency response curve of the audio signal, and then, taking a preset standard amplitude-frequency responsecurve as a reference, debugging the measurement amplitude-frequency response curve according to an amplitude-frequency curve fitting target curve algorithm, obtaining a target amplitude-frequency response curve, obtaining corresponding DSP parameters of the target amplitude-frequency response curve, setting the DSP parameters to a sound box DSP, so as to complete debugging of the sound box in a sound system. Therefore, according to the embodiments of the invention, the sound debugging operation can be simplified, and the debugging efficiency is improved.