52 results about "Chirp rate" patented technology

The invention discloses a rolling bearing fault time-varying instantaneous feature enhancement and extraction method. The method comprises the following steps: acquiring an original bearing fault signal; decomposing an original bearing fault signal based on an adaptive noise complete set empirical mode decomposition method to obtain a series of intrinsic mode function components; component properties are distinguished based on a correlation coefficient hopping criterion, and denoising is carried out; mapping the bearing fault signal after noise reduction to a time-frequency chirp rate space based on a local maximum frequency chirp rate synchronous compression chirp transformation method; and extracting a time-frequency chirp rate coefficient reflecting fault time-varying instantaneous characteristics from the extruded time-frequency chirp rate space, reconstructing a bearing fault impact component, performing Hilbert envelope analysis on the bearing fault impact component, and identifying the characteristic frequency of the bearing fault. According to the method, the fault time-varying instantaneous characteristics of the rolling bearing can be clearly and accurately extracted, and the method has a good engineering application prospect.

The invention relates to the technical field of power equipment state monitoring, and discloses a partial discharge detection method and system based on synchronous compression wavelet-synchronous extrusion. The method comprises the following steps: preprocessing a partial discharge signal; calculating a coefficient through continuous wavelet transform and estimating an instantaneous frequency and a chirp rate; synchronous compression is carried out to compensate the phase, and scale remarking is carried out; energy is reallocated to a frequency axis through synchronous extrusion, and a high-aggregation-degree time-frequency diagram is generated; extracting a peak domain based on the saliency spectrum, demodulating along a ridge line, and estimating event parameters; and finally, robust judgment and auditing output are completed by using the joint statistics. According to the method, the sensitivity and robustness of partial discharge signal detection under the conditions of low signal-to-noise ratio and strong interference are remarkably improved.

The application discloses a chirp rate measurement method of a chirped volume grating, and comprises the following steps: constructing a measurement light path; starting a laser and an energy detector; adjusting the included angle and relative position of a to-be-measured chirped volume grating sample and a laser output light beam by adjusting an angle adjusting table and a translation table, recording the angle and position when the chirped volume grating diffracts, and calculating an angle average value; and calculating the chirp rate of the to-be-measured chirped volume grating sample according to a formula. The measurement principle is simple, the calculation method is clear, and the chirp rate of a chirped volume grating of any specification can be measured.

An elastic wave device 1 according to the present invention comprises a support member 3, a piezoelectric film including a piezoelectric layer 6, and at least one IDT electrode 7 having a plurality of electrode fingers. In the at least one IDT electrode 7, the electrode finger pitches and / or the widths of the electrode fingers vary. When one electrode finger pitch is denoted as P1 and the other electrode finger pitch is denoted as P2 in three continuous electrode fingers, and Mmax represents the widest width and Mmin represents the narrowest width among the widths of the three continuous electrode fingers, an adjacent chirp rate represented by at least one of formulae (1) and (2) is larger than 0° in at least a part of the at least one IDT electrode 7. In the entirety of the IDT electrode 7, an adjacent chirp rate represented by each of formulae (1) and (2) is 0.6° or less.　(1): Arctan [|P1-P2| / (P1+P2)] (2): Arctan [|Mmax-Mmin| / (P1+P2)]

This application relates to a method, device, and apparatus for estimating parameters of ground moving targets based on shadows. The method constructs a geometric model for imaging moving targets using terahertz video SAR (terahertz SAR) in a spotlight mode, and based on this geometric model, obtains a mathematical model of the moving target's echo. After representing the echo signal obtained by detecting a ground moving scene using the terahertz video SAR using this mathematical model, the method estimates the target's range velocity by the relative offset between the target image and the shadow in azimuth, estimates the target's azimuth velocity by frequency broadening between the target image and the shadow in azimuth, and estimates the target's range acceleration by compensating for the quadratic phase and modulating the quadratic phase frequency. This method enables accurate target parameter estimation.

This signal parameter estimation device is configured to comprise: a candidate value setting unit (1) that sets a plurality of candidate values for a chirp rate representing the ratio of chirp frequency width to chirp time width of a reception signal, which is an observation signal of a chirp signal that is the target for parameter estimation; and a candidate value selection unit (2) that multiplies the reception signal by opposite-phase components of each of the candidate values set by the candidate value setting unit (1), converts the reception signals after the opposite-phase component multiplication to signals of a frequency region, and selects, from among the plurality of candidate values, the candidate value for which an electrical power peak value of the signal of the frequency region is relatively larger. Moreover, the signal parameter estimation device comprises: a frequency width estimation unit (3) that multiplies the reception signal, which is the observation signal, by the opposite-phase component of the candidate value selected by the candidate value selection unit (2), converts the reception signal after the opposite phase component multiplication to a signal of the frequency region, and, on the basis of frequency intervals included in the post-conversion signal of the frequency region which correspond to a plurality of electrical power peak values, estimates the chirp frequency width; and a time width estimation unit (4) that estimates the chirp time width from the chirp frequency width estimated by the frequency width estimation unit (3) and the candidate value selected by the candidate value selection unit (2).

The invention relates to the technical field of signal processing, in particular to a time-frequency analysis method for a non-stationary signal under coexistence of harmonic waves and pulses, which comprises the following steps: acquiring a linear frequency modulation signal in which a harmonic component and a pulse component exist at the same time, and solving a threshold value compared with a chirp rate; calculating the chirp rate of each time frequency point of the linear frequency modulation signal based on a chirp rate estimator; when the chirp rate of a certain time-frequency point is less than or equal to a threshold value, considering that the time-frequency point tends to the harmonic characteristic, and redistributing the time-frequency point in the frequency direction; when the chirp rate of a certain time-frequency point is greater than a threshold value, considering that the time-frequency point tends to pulse characteristics, and redistributing the time-frequency point in the time direction; and adding the two redistribution results to obtain the time-frequency representation of the linear frequency modulation signal. According to the method, the time-frequency representation with concentrated energy can be generated for the harmonic and pulse components in the signal at the same time.

The invention discloses a three-dimensional Chirplet time-frequency analysis method based on bidirectional sparse search, and belongs to the technical field of signal processing and acoustic target recognition. Comprising the following steps: acquiring a to-be-analyzed non-stationary multi-component signal, and performing three-dimensional Chirplet transformation on the to-be-analyzed non-stationary multi-component signal to obtain three-dimensional time-frequency-chirp rate combined feature mapping fusing time, frequency and chirp rate features; selecting a plurality of initialized candidate points from the three-dimensional time-frequency-chirp rate joint feature mapping, and performing forward and backward path search on the initialized candidate points to obtain a sparse ridge track; and sparse ridge line components are extracted based on the sparse ridge line trajectory, residual signal energy updating is performed on the three-dimensional time-frequency-chirp rate joint features based on the sparse ridge line components, and time domain representation fusing all the sparse ridge line components is output. The method is suitable for sparse feature extraction and component separation of a non-stationary multi-component signal, cross interference and background noise can be effectively suppressed, and the identification capability and reconstruction precision of a signal structure are improved.

The invention provides a chirped laser source device for providing a chirped laser beam having a chirp rate that is of at least 20 MHz / V. In accordance with preferred embodiments, the achievable chirp rate may be much higher. As such, the proposed device enables a variety of applications that benefit from a laser beam having an elevated chirp rate and therefore a large spectral width. In particular, the proposed chirped laser source device allows to produce laser beams that enable CRBS analysis of air or of gases having very high temperatures, which is not achievable with known chirped laser sources.

A light detection and ranging (LIDAR) system transmits, towards a target, a set of chirp signals. The LIDAR system receives from the target, a set of adjusted chirp signals. The LIDAR system then determines, based on the set of adjusted chirp signals, a degree of ghosting mitigation to compensate for a ghost target appearing in a point cloud at a location where no real target exists.

The embodiment of the invention relates to the field of signal processing, in particular to an underwater acoustic LFM signal frequency modulation rate detection method and device based on a frequency dispersion condition. A specific embodiment of the method comprises the following steps: determining an initial LFM signal, a channel model and an initial receiving signal; based on a preset fractional order Fourier transform formula, performing FrFT correction processing on the initial LFM signal and the initial receiving signal to generate a CIR; performing fast frequency dispersion elimination conversion processing on the CIR to generate a target frequency dispersion elimination signal; and determining an optimal p value and a Chirp rate estimation value based on a preset tap delay model and the target frequency dispersion elimination signal. According to the embodiment, a relatively accurate Chirp rate estimation value can be obtained.

The FMCW LiDAR system includes an optical drive electronic circuit to receive a reference frequency signal and a beat frequency signal to generate a drive signal. The optical drive electronic circuit includes a TDC to calculate a phase difference between the reference frequency signal and the beat frequency signal and a digital ramp control to: provided the phase difference is a positive value, produce a ramp down control signal to increase a current chirp rate to an increased chirp rate; provided the phase difference is a negative value, produce a ramp up control signal to decrease the current chirp rate to a decreased chirp rate. The optical drive electronic circuit includes a digital integrator to generate a digital output based on at least one of the ramp down control signal or the ramp up control signal and a DAC to convert the digital output to an analog output.

The application discloses a method for estimating the sweep period of linear frequency modulation interference, and is mainly used for estimating the sweep period of linear frequency modulation interference in the field of signal processing and the like. The method can preset a transform order and a calculation parameter, generates a coefficient required for fractional order Fourier transform calculation, and does not need to normalize the dimension of input data in advance. According to different transform orders, fractional order Fourier transform calculation is performed on input data, until the average peak value interval is calculated after multiple peak values appear in the transform domain. Finally, the sweep period is estimated according to the current searched transform order and the average peak value interval. The method greatly reduces the calculation complexity of the sweep period estimation, multiplexes the anti-interference hardware architecture, saves the hardware resources, does not need to normalize the dimension of input data in advance, increases the compatibility of the method, and does not need to search the period with a fixed length, thereby reducing the calculation amount and increasing the estimation accuracy.

The invention discloses a chirp modulation frequency offset and timing joint estimation signal synchronization method and a chirp modulation frequency offset and timing joint estimation signal synchronization system, which relate to wireless communication and signal processing technologies, and comprise the following steps: completing coarse synchronization by using a demodulation result of an upper chirp in a lead code; the method comprises the following steps: accurately estimating frequency offset and time offset of signals based on a forward chirp signal and a reverse chirp signal in a chirp signal pilot frequency sequence synchronization head, intercepting a section of forward sweep frequency signal at the synchronization head, and performing refined spectrum estimation on an upper chirp spectrum peak position of the forward sweep frequency signal; intercepting a section of reverse frequency sweep signal at the synchronization head, and performing refined frequency spectrum estimation on the lower chirp spectrum peak position of the reverse frequency sweep signal; and resolving a peak value generated by a signal frequency spectrum according to refined frequency spectrum estimation results of the forward frequency sweep signal and the reverse frequency sweep signal to obtain a frequency offset compensation result. According to the method, errors generated by the system can be estimated with fewer symbols, and the method is applicable to different chirp rate conditions.

The application discloses a kind of laser detection device and method, belong to laser detection technical field, the device includes beam output module, light splitting module, optical path multiplexing module, two coherent mixing modules and signal processing module;Beam output module outputs the positive and negative double-chirp laser of frequency-modulated time sequence synchronization of different wavelength, chirp rate absolute value equal, after light splitting, optical path multiplexing, get local light and echo light, two coherent mixing modules generate four-way quadrature beat frequency signal, signal processing module does product subtraction and addition operation to four-way beat frequency signal and constructs complex signal, offset Doppler broadening interference introduced by rotating polygon mirror, again Fourier transform, peak searching obtains intermediate frequency parameter and calculates target vector velocity, the application can completely eliminate the influence of Doppler broadening on speed measurement, significantly improve speed measurement precision.

The application provides a real-time correction method and device for detecting equipment operation parameters, equipment and a medium, and belongs to the technical field of ore body exploration. The method comprises the following steps: acquiring point cloud data of a target area based on a detecting equipment; calling a preset dynamic local quality model to perform spatial division and physical property identification processing on the point cloud data to obtain a quality voxel; performing multipole moment expansion and gravity projection processing on the quality voxel to obtain a terrain gravity correction number; performing frequency shift conversion and modulation processing on a frequency shift parameter of a radar scanner based on the terrain gravity correction number to obtain a compensation frequency shift parameter, which is used for adjusting a laser chirp rate to offset a phase shift of the radar scanner; and correcting an operation parameter of a gravimeter in the detecting equipment based on the compensation frequency shift parameter. The above scheme can effectively improve the stability of the detecting equipment in performing an exploration task.

The invention discloses a multi-focal-length laser focusing system and method, and belongs to the technical field of photoelectrons and lasers. The multi-focal-length laser focusing system comprises a laser beam splitting unit, a light path conversion unit and a laser multi-focal-length focusing unit. The laser beam splitting unit is used for splitting an incident laser beam; the light path conversion unit collimates the plurality of beam splitting lasers and stretches the collimated laser beams; the laser multi-focal-length focusing unit comprises a first acousto-optic driving source and a first acousto-optic device, the first acousto-optic driving source sequentially generates a plurality of chirp signals with adjustable energy, and the first acousto-optic device forms a plurality of acoustic sub-gratings with different grating intervals; and the acoustic sub-grating performs focusing with different focal lengths on the split light beams which are shaped by the light path conversion unit. By adjusting the angle and the intensity of the beam splitting laser and the number and the chirp rate of the chirp signals, the focusing number and the focusing focal length of the beam splitting laser are controlled. The adjustable multi-beam multi-focal-length focusing is realized, and the size of the device is reduced.

The invention discloses a multi-chirp rate index modulation method and system based on a ZC sequence. The method comprises the following steps: acquiring a data stream to be transmitted; converting the data stream to be transmitted into a plurality of first index symbols by using a combination number method; respectively converting each first index symbol into a corresponding ZC sequence; combining each ZC sequence to form a sequence to be transmitted; performing digital-to-analog conversion on the sequence to be transmitted to obtain a transmission signal data stream; acquiring a sending signal data stream; after analog-to-digital conversion, a converted receiving data stream is obtained; demodulating the converted receiving data stream for multiple times to obtain a plurality of demodulation results; performing modulo operation on all the demodulation results to obtain a result after modulo operation; mapping and sorting the result after the modulo operation to obtain a second index symbol; and converting the second index symbol into a received data stream by using a combination number method. The modulation method has the advantages of being high in transmission rate and small in application limitation.

To provide a distance and velocity measurement apparatus that can be adopted preferably in a LiDAR or a sensor for a robot, wherein the apparatus can prevent deterioration of SN ratio even in a case where an object in an external environment vibrates. A LiDAR 20 according to the present embodiment includes a first laser apparatus 1a, a second laser apparatus 1b, a polarization-maintaining type optical fiber 2, a WDM filter 6, an optical fiber coupler 3a, an optical amplifier 11, an input / output unit 4, an optical scanner 5, a second optical fiber coupler 3b, a balanced photodetector 7, and a square-law detector 9. Further, a delay line 10 composed of a polarization-maintaining optical fiber is provided on the local port 2b. The first laser apparatus 1a includes a device for generating a first laser light having a first wavelength and a first chirp rate in an interior thereof, and the second laser apparatus 1b includes a device for generating a second laser light having a second wavelength that differs from the first wavelength and a second chirp rate that differs from the first chirp rate.

The invention discloses an SAR azimuth undersampling imaging method and system based on deep learning, and the method comprises the steps: obtaining an SAR data set which comprises fully-sampled SAR images and echo data corresponding to each SAR image, and enabling the SAR data set to serve as the input of a deep expansion network; the method comprises the following steps: acquiring an SAR Doppler center frequency, a frequency modulation rate, a carrier frequency and a satellite equivalent speed, and designing an imaging operator by using a chirp scaling algorithm in SAR imaging; constructing a deep expansion network based on a Unet architecture, and performing image restoration on the echo signal; the deep expansion network is trained, a model weight file with the minimum loss is stored, and parameters in the weight file comprise parameters in a convolutional layer and a nonlinear activation function in a denoising device, learnable parameters in conjugate gradient descent and parameters in an undersampling mode; and loading a pre-trained weight file, performing reasoning by using the expanded network model, obtaining a deblurring imaging result, and obtaining an optimized undersampling strategy. The azimuth ambiguity suppression effect realized by the method is good.

The present application relates to a sparse time-frequency-chirp rate characterization reconstruction method based on tail minimization. After constructing a parametric sparse optimization model and using the alternating direction method of multipliers (ADMM) to solve it, at the end of multiple iterations in one round of solution, the tail support set of the frequency-chirp rate reconstruction characterization obtained in the current iteration is calculated, and the global optimization variable is updated according to the tail support set, and then it is brought into the subsequent solution of the ADMM, so that in the process of multiple solutions, the energy of the target support set in the global optimization variable is more prominent. Using this method can make the target micro-motion features extracted in complex scenarios more accurate.

The invention relates to a system and a method for simultaneous range and velocity measurement in an FMCW LiDAR system. A first light source produces first light having a first frequency that varies according to a first chirp rate. A second light source produces second light having a second frequency that is constant or that varies according to a second chirp rate. A splitter separates the measuring light into reference light and output light, and a scanning unit directs the output light towards an object and receives input light that is obtained by reflection of the output light at the object. A detector detects a superposition of the reference light and the input light. A computing unit computes unambiguously the range and relative velocity by analyzing beat frequencies resulting from the superposition. Ambiguities due to Doppler frequency shifts are removed by performing a decision tree analysis.

Embodiments of the present application provide a method for measuring the absolute gravity value and an electronic device, relating to the technical field of absolute gravity value measurement. The method includes: determining a target interference fringe corresponding to the set pulse time interval in a target chirp rate range according to the corresponding relationship between the laser frequency chirp rate and the atomic ground state probability; obtaining target interference fringes corresponding to different set pulse time intervals, and determining a set of valley chirp rates corresponding to each target interference fringe, to obtain multiple sets of valley chirp rates; determining the chirp rate of the center extreme point of the interference fringe based on the valley chirp rates in the multiple sets of valley chirp rates, and calculating the absolute gravity value according to the chirp rate of the center extreme point of the interference fringe. The technical solution of the embodiments of the present application can improve the measurement efficiency of the absolute gravity value and has little impact on its measurement accuracy.

The application discloses a time-frequency analysis method and system for bearing fault signal classification processing, electronic equipment and a computer readable storage medium, and belongs to the technical field of time-frequency analysis of non-stationary rotating machinery fault signals. A set of signal classification processing strategies are introduced, and the initial short-time Fourier transform time-frequency representation of the signal is divided into two categories. The time direction compression is adopted for one category with a chirp rate greater than a threshold value, and the frequency direction compression is adopted for the other category with a chirp rate less than the threshold value, so as to reduce the serious error of the frequency direction compression in the case of facing the signal frame with a large chirp rate and the time direction compression in the case of facing the signal frame with a small chirp rate. In the noisy working environment of the rotating machinery, the method can more accurately extract the fault characteristic frequency of the bearing, and effectively diagnose the health condition of the machinery. The problems that the fault characteristic frequency of the bearing cannot be accurately extracted and the health condition of the machinery cannot be accurately diagnosed in the prior art are solved.

The application discloses a three-dimensional extraction method of complex superimposed dense channel reservoir based on statistical linear frequency modulation, and comprises the following steps: S1, inputting a seismic signal x(t) to be analyzed, wherein t is time; S2, constructing a linear chirp transform in a time-frequency-chirp rate (TFC) three-dimensional space, wherein omega is frequency, and beta is a chirp rate; S3, combining a matrix calculation method, and introducing a group of bases to represent an instantaneous attribute value of a single-component signal; S4, introducing a sliding real-value frequency filter H(omega) to realize local representation of an instantaneous attribute value of a multi-component cross signal; S5, according to an inner product formula, constructing a statistical linear frequency modulation filter estimation and a time-frequency coefficient used for extracting an original time-frequency spectrum instantaneous frequency and an instantaneous chirp rate curve in the TFC space, and obtaining a statistical linear frequency modulation three-dimensional extraction transform value T x (t, omega, beta); S6, performing modulus operation on T x (t, omega, beta), and obtaining a time-frequency spectrum of the statistical linear frequency modulation three-dimensional extraction transform, so that the purpose of effectively identifying a complex superimposed dense channel sandstone reservoir is achieved.

The invention discloses a time-frequency detection method for an early rub-impact fault of a steam turbine rotor, and the method comprises the steps: S1, carrying out the vibration signal collection of the steam turbine rotor, and obtaining a vibration signal; s2, calculating a time second-order synchronous extraction operator and a frequency second-order synchronous extraction operator under a second-order model through the vibration signal; s3, iterating the time second-order synchronous extraction operator and the frequency second-order synchronous extraction operator to obtain a lifting extraction operator; s4, performing chirp rate estimation on the time second-order synchronous extraction operator and the frequency second-order synchronous extraction operator to obtain an estimated time-frequency rotation angle; s5, using a chirp fusion technology for the estimated time-frequency rotation angle to obtain a fusion time-frequency graph; and S6, turbine rotor fault features are extracted from the fusion time-frequency diagram through a bidirectional extraction technology. According to the method, the calculation cost is saved, the calculation efficiency is improved, the regularity of fault features can be highlighted, and a sufficient judgment basis is provided for early rub-impact fault diagnosis.

A method of performing coherent anti-stokes Raman spectroscopy (CARS) includes generating first and second optical pulse trains having different and adjustable repetition rates. One of the pulse trains is directed in a CW direction and the other in a CCW direction. A frequency shift and a first linear chirp is applied to optical pulses in the first optical pulse train. A second linear chirp is applied to optical pulses in the second optical pulse train. The first and second linear chirps having a common chirp rate. One of the chirped optical pulse trains is used as a pump beam and the other is used as a Stokes beam. The first and second chirped optical pulse trains are combined to define a combined beam. The combined beam is provided to a CARS spectroscopic system for exciting a resonant mode in a sample and generating a CARS signal.

This user equipment may acquire a first identifier and a second identifier on the basis of a primary synchronization signal and a secondary synchronization signal received on a cell, and acquire a physical cell identifier of the cell on the basis of the first identifier and the second identifier. The first identifier is one of P first-identifier candidates respectively associated with P primary synchronization signal candidates, where P is a positive integer. The P primary synchronization signal candidates may be respectively based on P orthogonal chirp signals, wherein the P orthogonal chirp signals may include at least a first orthogonal chirp signal and a last orthogonal chirp signal among N orthogonal chirp signals of the same chirp rate.

The invention discloses a gravimeter measuring range automatic matching method and computer equipment, and the method comprises the steps: roughly calculating a local gravity value through employing local latitude and longitude and altitude, and carrying out the rough adjustment of the measuring range of a gravimeter; changing the free evolution time of the gravimeter by controlling a time sequence to obtain atomic interference fringes at different evolution time; the chirp rate is used as an independent variable, the atomic transition probability is used as a dependent variable, data fitting is carried out on the atomic interference fringes, and a chirp rate value corresponding to the sine curve valley bottom is obtained; and obtaining a scatter diagram by taking the free evolution time as an independent variable and the chirp rate value corresponding to the valley bottom of the sine curve as a dependent variable, fitting to obtain a public valley bottom through a shortest path algorithm, obtaining a local gravity value, and finishing the fine adjustment of the range of the gravimeter. The problems that an existing method is complex in operation, low in automation level and long in consumed time can be solved.

The application relates to the field of biometric identification technology and discloses a multi-modal handwriting dynamic feature extraction and identification system. The system synchronously acquires macro kinematic sequences and micro acoustic emission sequences, performs time axis regularization based on a bottom-layer hardware interrupt signal, extracts instantaneous geometric singular points of the macro kinematic sequences, combines stress checking to intercept effective micro windows, performs phase space line integral calculation in the effective micro windows to extract macro dissipation work parameters, applies phase compensation to the micro acoustic emission sequences based on corresponding physical coordinates to realize beam forming, acquires micro friction frequency response chirp rates, fuses the dissipation work parameters and the chirp rates to generate high-dimensional identification feature vectors, and inputs the high-dimensional identification feature vectors into a classifier to output a judgment result. The application quantizes a real dynamic physical work process of writing, effectively resists high-precision mechanical arm impersonation attacks, overcomes the defects that a single-channel acoustic acquisition is susceptible to bottom noise and dispersion interference, and improves identification stability in a complex environment.