35 results about "Coherence (signal processing)" patented technology

The invention belongs to the technical field of radar signal processing, and particularly discloses a free-air high-speed target detection method based on long-time accumulation, and the method comprises the steps: segmenting an echo signal after pulse compression according to the number of pulses, and compensating the range walk and Doppler spread enveloped by the echo signal in each segment; performing intra-segment phase-coherent accumulation on the result after the compensation in each segment; and finally, carrying out inter-segment envelope movement and non-coherent accumulation on all echo signals, so that the energy of the echo signals is effectively accumulated. A long-time accumulation method of time segmentation, intra-segment coherent accumulation and inter-segment non-coherent accumulation is adopted, so that the problem of long-time coherent accumulation calculation amount is solved, and the problem of poor coherence of echo signals is solved; and the detection performance is improved, and engineering realization is easy.

The present invention discloses a task-state electroencephalogram signal analysis method based on algebraic topology and belongs to specific applications of a complex network analysis technology in the field of neural signal processing. The method comprises the following steps: using electroencephalogram signals as a data source, constructing distance relationship of electrodes at different spatial positions by calculating coherence between the electrodes, using the algebraic topology method to dynamically construct a simplex-based brain functional network, characterizing task-state electroencephalogram signal neural characteristics, further analyzing nature of the brain functional network by calculating Betti number and Euler's characteristic number, and realizing a quantitative study ofa brain function model of subjects under a task state. The task-state electroencephalogram signal analysis method is verified to perform well in the task-state electroencephalogram signal analysis, provides the new method for measuring neural responses in the task state, explores new rules and evidence for brain-like computing, thus can inspire artificial intelligence frameworks and specific algorithms design, etc., and promotes development of a new generation of artificial intelligence.

The invention provides a device and a method for measuring the thickness and the refractive index of a thin film, and belongs to the field of optical measurement. The device comprises a low-coherence light source, a light splitting assembly, a reflecting mirror, a sample groove, a spectrograph and a signal processing unit. Light emitted from the low-coherence light source enters the light splitting assembly, and the light is split into reference light and sample light through the light splitting assembly. The reference light irradiates on the reflecting mirror; sample light enters the sample groove perpendicular to the side face of the sample groove. The reference light reflected by the reflecting mirror and the sample light reflected by the sample groove and the sample to be detected are reflected into the light splitting assembly and are output into the spectrograph. The method comprises: demodulating by combining the frequency and phase of Fourier transform, respectively measuring the optical path after the sample groove is vacant and after the sample is placed, and pouring a liquid with known refractive index into the sample groove for measuring the optical path for the thin film. The measuring method based on phase-sensitive optical coherence tomography has the advantages of nanoscale precision, simplicity in operation and applicability to films in various states.

The invention relates to a heart disease computer-aided classification method based on continuous coherence and Fourier transform, and belongs to the technical field of computer-aided diagnosis and signal processing. According to the method, the electrocardiogram is regarded as a one-dimensional time sequence signal, the signal is converted into the point cloud through Fourier transform, and the overall structural difference of the point cloud is researched through continuous homology extraction of topological characteristics, so that original signals are classified, the application effect is ensured, and the defects that information is lost and the method is easily interfered by fine factors are overcome. Fourier transform is a powerful tool for analyzing periodic signals, and due to completeness of a standard orthogonal basis, information of the signals can be completely converted into information of point clouds. The method can keep the accuracy, can greatly reduce the calculation amount, is based on the topological characteristics of the signals, does not depend on adjustment parameters, and has remarkable advantages. The method has a wide application prospect in the fields of biomedicine, signal processing and the like besides the field of electrocardiosignal classification.

The invention relates to an observation matrix construction method based on a low-coherence unit norm tight frame, and belongs to the technical field of signal processing, and the method comprises thesteps: S1, initializing an initial observation matrix phi 0 into a random part Fourier matrix, and enabling the initial observation matrix phi 0 to serve as an initial alpha tight frame F; s2, calculating a Gram matrix corresponding to the framework F, and projecting the matrix to a structure constraint set of a tight framework by using a contraction function to generate a new Gram matrix; s3, updating the Gram matrix through a weighted iteration process; s4, reducing the rank of the new Gram matrix, calculating the square root of the new Gram matrix, and finding out a tight frame closest toa unit norm tight frame; and S5, solving the optimal target function to obtain an observation matrix. According to the method, the mutual interference coefficient between the observation matrix and the sparse basis is reduced, the dependence degree on signal sparsity is reduced, the problem that an ETF frame is difficult to construct is avoided, the initial observation matrix is initialized into apart of Fourier matrix, the calculation complexity is reduced, and the pressure of storage and processing equipment is reduced.

The invention discloses an ultra-short baseline underwater sound source positioning method based on a two-dimensional arbitrary array space, and belongs to the multidisciplinary crossing field of array signal processing, oceanography and the like. According to the invention, an ultra-short baseline positioning system is adopted, an array structure in a quaternary cross array form is designed, and any array mode is adopted to obtain a received signal; and for a pitch angle and an azimuth angle theta of an incident signal, a focusing matrix is constructed by using a coherent signal subspace method based on a subspace-like MUSIC algorithm to focus broadband multi-frequency to a center frequency f0, and for a focused broadband signal, a two-dimensional angle joint spatial spectrum function is constructed by using a two-dimensional MUSIC improved algorithm, source target space positioning is carried out on broadband signals propagated underwater, and the problem that the precision of ocean broadband signal space positioning is insufficient is solved. Compared with a mainstream method based on time delay inequality, the ultra-short baseline underwater sound source positioning method based on the two-dimensional arbitrary array space can identify broadband signals under the condition of signal and noise coherence, and the positioning precision of the ultra-short baseline underwater sound source positioning method based on the two-dimensional arbitrary array space is higher than that of other comparison algorithms under the condition of different signal-to-noise ratios.

A coherence indicator of received signals is calculated for pixels with a small amount of calculation, and a high-quality ultrasound image is obtained. A plurality of types of images in which a sound speed for beamforming is changed into a plurality of types are generated. By arranging, in order of the sound speed for beamforming, signal intensities of the pixels at corresponding positions between the plurality of types of images, a change in signal intensities in a direction of the sound speed for beamforming is obtained. A coherence indicator representing coherence of the received signals used for beamforming of the pixels is calculated based on the obtained change in the signal intensities.

The invention relates to the technical field of radar systems, in particular to a software MIMO three-dimensional imaging radar system which comprises a signal processing subsystem, a control and data acquisition subsystem, a transmitting subsystem and a receiving subsystem. A digital waveform is generated by using a software control program in the control and data acquisition subsystem, the digital waveform is converted into analog baseband signals through the transmitting subsystem, the analog baseband signals are up-converted into radio frequency signals through a mixer, the radio frequency signals are divided into two paths by a power divider, one path of signals is used for signal transmitting, the other path of signals serves as reference signals and is transmitted to the receiving subsystem after being attenuated by 40dB, so that time, frequency and phase synchronization between transmitting and receiving is realized by utilizing the reference signals at the seam of the transmitting subsystem, and a receiving local oscillator and a transmitting local oscillator have coherence. Therefore, the MIMO radar system has the advantages of being low in cost, light in weight and high in resolution.

The invention discloses a semi-quantitative post-stack seismic fracture prediction method, which relates to the technical field of signal processing methods in the field of oil and gas seismic data interpretation. The method comprises the following steps of S1, obtaining initial seismic data, and carrying out structure guiding filtering on the initial seismic data to obtain first seismic data, S2, performing power exponent operation on the first seismic data S1 to obtain second seismic data S2 so as to improve the participation degree of weak reflection in the first seismic data, S3, using a third-generation coherence algorithm to perform coherence analysis on the second seismic data S2 based on dip angle scanning to obtain the maximum similarity coefficient C of each sample point in the seismic data and the corresponding dip angle and trend, and gathering the maximum similarity coefficients C of all sample points into a similarity number body, S4, enabling the maximum similarity coefficient C of each sample point in the similarity coefficient body obtained in the step S3 to be subjected to power respectively, and naming the index of power operation as a discontinuous sharpening index, and S5, completing drawing of a crack prediction result map by adopting a vector statistical mapping method.

This document describes a system and method for detecting domain names that exhibit Domain Generation Algorithm (DGA) like behaviours from a stream of Domain Name System (DNS) records. In particular, this document describes a system comprising a deep learning classifier (DL-C) module for receiving and filtering the stream of DNS records before the filtered DNS records, which have been determined to possess domain names that exhibit DGA behaviour are provided to a series filter-classifier (SFC) module. The SFC module then groups the records into various series based on source IP, destination IP and time. For each series, it then filters away records that do not exhibit the dominant DGA characteristics of the series. Finally, for each series, it makes use of the remaining DNS records' timestamps to generate a time series of DGA occurrences and then, using this time series of occurrences, determine the number of DGA bursts throughout the time period of analysis. An autoencoder-classifier (AE-C) then assigns coherence scores, by analysing correlations over a time period, to each series of DGA records based on its corresponding time series of DGA occurrences. A frequency spectrum analyser (FSA) module is then used to convert the time series of DGA occurrences into a frequency spectrum, before it identifies periodic DGA bursts occurring within each series of DGA records. The information generated by the FSA and AE-C modules together with the series of possible DGA domain names produced by the SFC module and other enriching details are then passed to an alert module which then uses this information to present and prioritize enriched DGA alerts.

The invention discloses an echo signal processing method, device and equipment and a computer readable storage medium, and belongs to the technical field of signal processing. The method comprises the following steps: acquiring a call state based on a far-end signal and a near-end signal; obtaining an estimated echo signal based on the far-end signal, and removing the estimated echo signal from the near-end signal to obtain an error signal; calculating an incoherence value of the far-end signal and the near-end signal and a coherence value of the near-end signal and the error signal; determining an inhibition factor based on the call state, the incoherence value and the coherence value; the error signal is processed based on the suppression factor. As the suppression factor is jointly determined based on the call state, the incoherence value of the far-end signal and the near-end signal and the coherence value of the near-end signal and the error signal, the suppression factor has high relevance with the call state, the far-end signal, the near-end signal and the error signal, and the error signal is processed by adopting the suppression factor, so that the error signal can be effectively suppressed. And the effect of weakening the residual echo signal in the error signal is good.

A dual microphone signal processing arrangement for reducing reverberation is described. Time domain microphone signals are developed from a pair of sensing microphones. These are converted to the time-frequency domain to produce complex value spectra signals. A binary gain function applies frequency-specific energy ratios between the spectra signals to produce transformed spectra signals. A sigmoid gain function based on an inter-microphone coherence value between the transformed spectra signals is applied to the transformed spectra signals to produce coherence adapted spectra signals. And an inverse time-frequency transformation is applied to the coherence adjusted spectra signals to produce time-domain reverberation-compensated microphone signals with reduced reverberation components.

The invention belongs to the technical field of ultra-wideband radar signal processing, and discloses an ultra-wideband MIMO radar vital sign detecting and positioning method. The method mainly comprises the following steps of: (1) rearranging echo data of multiple channels of an MIMO radar; (2) performing sequential inertial coherence imaging and compensation on a target area; (3) carrying out band-pass filtering along a time dimension; (4) calculating the position of a living body thoracic cavity surface; (5) removing clutter and direct current bias; (6) taking a phase to obtain vital sign signals; (7) separating breathing and heartbeat signals; (8) detecting breathing and heartbeat signal peak values, and calculating an instantaneous breathing rate and a heart rate; and (9) performing sliding time window dynamic measurement. According to the method of the invention, three-dimensional positioning and vital sign measurement can be carried out on trapped persons under ruins and in buildings; and the method is high in signal processing gain, high in positioning precision, good in real-time performance and can realize instantaneous respiration rate and heart rate measurement.

The invention discloses a pressure measuring device and method based on quadrature phase rapid demodulation and intensity compensation. The pressure measuring device comprises a wide-spectrum light source (1), an optical fiber circulator (2), a Fabry-Perot (F-P) pressure sensor (3), an optical fiber 1 * 3 coupler (4), a low-coherence interferometer (5), an intensity compensator (6), a photoelectric detector (13), a data acquisition card (7) and a signal processing unit (8). During measurement, the F-P pressure sensor (3) is used for performing pressure sensing and constructing a quadrature phase signal, real-time intensity compensation is used for reducing the influence of external interference factors on a demodulation result, a phase is quickly and inversely calculated through a four-quadrant arc tangent algorithm subjected to level compensation, and the phase is converted into a pressure value in real time through calibration-fitting. Compared with the prior art, the signal demodulation of the F-P pressure sensor (3) containing a plurality of cavities can be realized, the influence of signal intensity fluctuation on a demodulation result can be greatly reduced, and the stability and the accuracy of a demodulation system are remarkably improved.