116 results about "Fourth order cumulants" patented technology

The invention provides a multi-target near-and-far field mixed source positioning method and belongs to the field of the array signal processing technology. According to the method, firstly, a symmetric and homogeneous linear sensor array is arranged to receive a target signal, and then the observation signal form of a near-and-far field mixed source is determined. Secondly, a special third-order cyclic matrix is constructed based on the output of a properly selected sensor, and a direction matrix thereof only contains the azimuth information of a far-field source and the azimuth information of a near-field source. Thirdly, the eigenvalue of the third-order cyclic matrix is decomposed, so that a corresponding noise sub-space is obtained. Fourthly, a cyclic autocorrelation matrix based on the observation data of the entire matrix is calculated, and the eigenvalue of the cyclic autocorrelation matrix is decomposed. In this way, a corresponding noise sub-space is obtained. Fifthly, an already estimated azimuth is substituted to the two-dimensional MUSIC spectrum peak searching process, so that the estimation on the distance of the near-field source is realized. The application of four-order cumulants is avoided, and the calculation complexity of the algorithm is effectively reduced. The operation time of the algorithm is shortened. Meanwhile, the cyclic steady interference and the steady background noise are effectively suppressed. Moreover, the extra parameter matching process is avoided.

The invention provides a quick beamforming method capable of improving array resolution and gain, comprising the following steps: adopting the construction of a minimum redundant array to optimize an M-element uniform linear array into a P-element non-uniform linear array; carrying out FFT processing on primitive data of a P-element array; in a frequency domain, constructing a covariance matrix of data based on the uniform linear array in accordance with the array aperture extension characteristics of fourth-order cumulants; carrying out normalization processing on the beam space and carrying out estimation on a Bartlett spatial spectrum. By adopting the array aperture extension characteristics of the fourth-order cumulants, the invention realizes that the optimized element layout form is employed to obtain high resolution and overcomes the defects of high requirements of the original fourth-order cumulant-based methods on snapshots and great computational complexity to enable the computation process to be simple and easy to operate. When the signal to noise ratio is higher than the supercritical signal to noise ratio, the method of the invention has higher array gain than that of conventional beamforming. The normalization processing of the beam space realizes effective inhibition to background interference. The beamforming method of the invention is simple and easy to operate and is especially suitable for project application.

The invention discloses an algorithm for separating vibration signal blind sources under a strong noise environment. The method comprises the following steps: 1, de-noising a group of given mixed signals containing noise through a time delay autocorrelation method to acquire de-noised mixed signals; 2, performing mean value removal and steady whitening pretreatment on the mixed signals acquired in the first step to further reduce the influence of the noise signals on the separation result; and 3, calculating second-order and fourth-order cumulated amount of the initial separate signals, using the sum of diagonal elements of second-order and fourth-order cumulated amount matrixes as a cost function, and maximizing the cost function to similarly diagonalize the joints of the cumulated amount matrixes so as to realize the separation of the signals of the independent sources and acquire orthogonal separation matrixes. The method combines the conventional de-noising method and the blind separation algorithm to realize the separation of the mixed signals under the strong noise environment, and has the advantages of good separation effect, high convergence rate and de-noising effect free from the limitation of the set threshold value compared with the conventional algorithm.

The invention claims to protect a space time block coding (STBC) MC-CDMA (Multicarrier Code Division Multiple Access) signal blind identification method based on the cyclostationarity, and belongs to the technical field of signal processing. The method comprises the following steps: establishing a selection standard of signal correlation functions according to the baseband physical model, signal construction and matrix representation of an STBC MC-CDMA system, and estimating corresponding fourth-order cumulants of the correlation functions; combining a fourth-order cyclic cumulant with the parameter of a channel to establish a cyclic statistic; and extracting a detection threshold according to the detection of cycle frequency, and making a judgment by comparing the detection threshold with the cyclic statistic to realize identification. As indicated by computer simulation, STBCMC-CDMA signals can be effectively identified with low complexity by adopting an algorithm adopted in the invention, and working under the condition of low input signal to noise ratio is feasible. Meanwhile, compared with a conventional identification algorithm, the algorithm adopted in the invention has the advantage that the influence of random noise is reduced by using the advantage of the fourth-order cyclic cumulant, so that the system performance is improved.

The invention discloses an ultrasonic receiving array orientation method for transformer partial discharge positioning. According to the method, an ultrasonic receiving array which is arranged along the array edge or the center line of a planar array and is in an L shape or in a cross shape is used. The method comprises the steps that broadband focusing and array expansion are combined, focusing operation is conducted on an ultrasonic array receiving signal of a broadband first, a broadband ultrasonic signal generated through partial discharge is segmented according to time, a focusing matrix is calculated through noiseless data, and the signal is focused on the same frequency band; then, virtual expansion is conducted on the array through a fourth order cumulant algorithm, and a data covariance matrix of the array after virtual expansion is replaced by an unexpanded fourth order cumulant matrix which is formed in sequence of an original array; at last, the partial discharge incoming wave direction of the array after virtual expansion is estimated through a multi-signal sorting algorithm.

The invention discloses a high-order cumulant based bistatic MIMO (Multiple Input Multiple Output) radar parameter estimation method. A joint estimation method of DOD (Direction of Departure), DOA (Direction of Arrival) and Doppler frequency of targets under a gauss color noise background is given out according to bistatic MIMO radar echo signal characteristics through a characteristic that high-order cumulant is insensitive to gauss color noise. The high-order cumulant based bistatic MIMO radar parameter estimation method comprises constructing two opposite angle section matrixes of cross-fourth-order cumulant of output signals of adjacent matched filters through airspace and time domain information of the bistatic MIMO radar; decomposing a singular value of the opposite angle section matrixes of the four-order cumulant, estimating the number of targets, reducing dimensions through eigenvalues and eigenvectors and constructing a new matrix; obtaining joint estimation of the Doppler frequency, the DOD and the DOA of the targets through the eigenvalues and eigenvectors of the novel matrix. According to the high-order cumulant based bistatic MIMO radar parameter estimation method which is an effective bistatic MIMO radar parameter estimation method, a target parameter estimation process has no specific requirements for the number of transmission array elements and receiving array elements.

The invention discloses a direction-of-arrival (DOA) angle estimation method based on a dual-layer nested array and mainly aims at solving the problems of heavy computation, low quantity of identified information sources and great estimation error in the prior art. The DOA angle estimation method comprises the following implementation steps: firstly, respectively constructing a first-layer nested array and a second-layer nested array; secondly, acquiring an output signal of the first-layer nested array and an output signal of the second-layer nested array; thirdly, calculating all fourth-order cumulants according to the output signal of the first-layer nested array and the output signal of the second-layer nested array to form a fourth-order cumulant vector; fourthly, constructing an over-complete base according to the fourth-order cumulant vector, and defining an airspace sparse vector; fifthly, converting detection of an airspace DOA angle estimation into solving of a sparse constraint equation; sixthly, obtaining a most sparse solution of the airspace sparse vector by using a convex optimization method; seventhly, drawing an amplitude spectrum according to the most sparse solution to obtain the DOA angle. According to the DOA angle estimation method disclosed by the invention, the quantity of information sources which can be identified is greatly increased under the condition of limited array element quantity; the DOA angle estimation method can be used for target reconnaissance and passive location.

The invention discloses a hybrid matrix recognition method in underdetermined blind source separation based on tensor regular decomposition. The method mainly solves the problem that in the prior art, hybrid matrix estimation is limited by specific conditions. The method includes the implementation steps that (1), source signals are sampled and observation data are acquired; (2), four-order covariance matrixes in different time delays are calculated through four-order cumulants of the observation data; (3), the four-order covariance matrix in different time delays are expanded into a three-order tensor mode; (4), tensor regular decomposition is conducted on three-order tensors, and a Khatri-Rao product matrix of a hybrid matrix to be recognized is acquired; (5), the product matrix is processed through an eigenvalue decomposition method, and an estimated value of the hybrid matrix is acquired. The method has the advantage of being high in recognition accuracy and can be used in the fields of voice, communication, radar and biomedicine and used for underdetermined blind source separation under the time-frequency aliasing condition.

The embodiment of the invention provides a method and device for extracting hybrid-phase seismic wavelets, wherein the method comprises the following steps of: calculating fourth-order cumulants of seismic data; smoothing the fourth-order cumulants of the seismic data by using three-dimensional hysteretic window functions and estimating three spectrums of the seismic wavelets; and extracting the hybrid-phase seismic wavelets by using the three spectrums of the seismic wavelets. With the embodiment of the invention, the estimation precisions of high-order spectrums and wavelets can be improved.

The invention discloses an arrival direction estimation method based on conjugation expansion. The method comprises the following steps of: firstly calculating and receiving a second order statistic between signals, obtaining a conjugation matrix of an oriented matrix by utilizing the property of a delay self-correlation function, then constructing a new pseudo snapshot matrix by utilizing delay sampling of an extensible vector, and finally estimating an arrival direction of a signal on the matrix by adopting a fourth-order cumulant method. By virtue of a signal arrival direction estimation method based on array extension, the number of estimated signal arrival directions is greatly increased and signal arrival direction estimation accuracy can be improved.

The invention provides a hybrid field signal source positioning method based on a symmetrical nested array. The hybrid field signal source positioning method comprises the following steps that an antenna array is set, wherein the antenna array is the symmetrical nested array; a far-field signal DOA is estimated to obtain an estimation value of the far-field signal DOA; the near field component isseparated from the far field component; a fourth-order cumulant virtual difference array of a near-field signal is calculated; an estimation value of the near-field signal DOA is obtained by using spectral peak search; and according to the near-field signal DOA estimation value, the near-field signal distance is estimated to obtain a near-field signal distance estimation value. The hybrid field signal source positioning method uses mixed-order statistics, and compared with a second-order statistic algorithm, the hybrid field signal source positioning method solves the problems of Gaussian noise interference and reduction of degree of freedom by half; the symmetric nested array and the fourth-order cumulant virtual differential array are used for improving the estimation accuracy of far-field DOA, near-field DOA and a near-field distance; oblique projection technology is utilized to separate the far-field and near-field components, and thus, it is not necessary to distinguish the far-field signal from the near-field signal according to distance parameters; and therefore, the number of search is reduced, and the computational complexity of the algorithm is further reduced.

The invention provides a multi-input and multi-output fast estimation method for radar receiving and transmitting angles under color-noise environment. The multi-input and multi-output fast estimation method comprises the following steps of: (1) carrying out matching and filtering on echo signals of all receiving array elements acquired by an A/D sampling module and obtaining received data of a virtual array; (2) carrying out rearrangement on the received data of the virtual array; (3) respectively carrying out subarray division on the received data and a rearranged matrix and meeting the characteristic of constant rotation of a transmitting end and a receiving end; (4) constructing two four-order cumulant matrix pairs; (5) obtaining signal subspaces including the characteristic of constant rotation in transmitting and receiving respectively by characteristic values; (6) estimating the receiving and transmitting angles of a target by utilizing an ESPRIT algorithm; and (7) realizing correct pairing of the receiving and transmitting angles by utilizing a maximum likelihood estimation method. The multi-input and multi-output fast estimation method provided by the invention has the advantages that the influence of Gaussian color noise can be effective inhibited, no special requirement exists for the quantity of transmitted/received array elements, the estimation accuracy is high, and the computation complexity is low, so that the multi-input and multi-output fast estimation method can be used for positioning targets on sea or at low altitude in tracking and guidance.

The invention provides a coherent signal direction finding method and system with an unknown signal source number. The coherent signal direction finding method includes the initiating step, the fourth-order cumulant matrix calculating step, the Toeplitz matrix establishing step, the intermediate variable setting step, the power spectrum calculating step and the searching step. The method and system have the advantages that decorrelation is conducted on coherent signals by establishing the Toeplitz matrix based on fourth-order cumulant, the Toeplitz matrix is of a joint diagonalization structure, and therefore no priori knowledge about the signal source number is needed; a new cost function is designed, and therefore the direction of arrival can be effectively estimated.

The embodiment of the invention relates to a signal processing method and a device. The method includes the following steps: in a period of time, receiving a mixed signal and obtaining the amplitude information of the received mixed signal; according to the third-order cumulant and the fourth-order cumulant of the amplitude information of the mixed signal, obtaining objective function through calculation; and using the objective function to obtain an independent signal in the mixed signal. The method can cause ICA algorithm to be applicable to unmixing treatment of various signals. Another method includes the following steps: using Newton iteration formula with a regulatory factor that can cause the objective function to descend according to given norm to conduct iterative treatment on initial weight vector until the iterated weight vector is converged, and obtaining the converged weight vector; receiving the mixed signal in a period of time and acquiring the amplitude information of the received mixed signal; and according to the converged weight vector, conducting unmixing treatment on the mixed signal and acquiring the independent signal in the mixed signal. The method has little restraint in selection of the initial value of the weight vector in partitioning matrix and high operation efficiency.

The invention discloses a fourth-order cumulant based co-prime array DOA (Direction of Arrival) angle estimation method, which mainly solves problems in the prior art that the utilization rate of array elements is low and that the signal identification number is small. The estimation method comprises the implementation steps of 1) respectively building a one-layer co-prime array and a two-layer co-prime array; 2) acquiring an output signal of the one-layer co-prime array and an output signal of the two-layer co-prime array; 3) calculating all fourth-order cumulants according to the output signal of the one-layer co-prime array and the output signal of the two-layer co-prime array; 4) constructing a fourth-order cumulant array according to all of the fourth-order cumulants; 5) calculating a noise sub-space of the fourth-order cumulant array; 6) calculating a spatial spectrum according to the noise sub-space of the fourth-order cumulants and an array manifold matrix; and 7) drawing an amplitude spectrum according to the spatial spectrum, and acquiring a DOA angle. The estimation method disclosed by the invention greatly improves the recognizable source number of an array under the condition that the number of array elements is limited, and is applicable to target reconnaissance and passive location.

A hybrid signal source locating method includes: constructing a fourth-order cumulant matrix according to the received data of a uniform linear array model; estimating the two-dimensional electronic angles of the hybrid signal source one by one; performing eigen-decomposition on the covariance matrix of the received data of the uniform linear array model to estimate the amplitude-phase response of the array model; using a plurality of calibration elements to eliminate the blurring phase in the amplitude-phase response; performing iterative operation on the three processes of the two-dimensional electronic angle estimation, the amplitude-phase response estimation, and the blurring phase elimination until the convergence; obtaining the convergence values of the amplitude-phase response diagonal matrix and the two-dimensional electronic angles; determining the type of the incident signal source; and outputting an incident signal source locating result. The present invention also provides a hybrid signal source positioning system. The implementation of the technical schemes provided by the invention can effectively reduce the computational complexity and shorten the operation time for locating, and meanwhile locates the hybrid signal source of the near field and the far field, improving the locating accuracy and the application range.

The invention relates to a transformer substation partial discharge locating method based on spatial spectrum unambiguous estimation. The transformer substation partial discharge locating method is technically characterized by comprising the following steps that a uniform circular array is selected as an ultrahigh frequency antenna array; the acquired partial discharge signals are focused by usingthe least square algorithm; the azimuth angle and the pitch angle of a partial discharge source are calculated by using a multi-signal classification algorithm based on the fourth-order cumulant; andthe position of the antenna array is changed and the electric power equipment having partial discharge is determined. Transformer substation partial discharge is located by using the method based onspatial spectrum unambiguous estimation so that partial discharge detecting and locating of all the electric power equipment in the open transformer substation can be realized; besides, the detectingsystem has small size and has no problem of direction finding ambiguity so that the problems that the present partial discharge detecting system based on the ultrahigh frequency antenna array has large size and inspection is not implemented easily can be effectively solved, the cost of the large installing equipment state online detecting device can be greatly reduced and the detecting efficiencycan be enhanced.

The invention discloses a high-order cumulant-based method for the multi-path propagation and separation of acoustic signals. According to the technical scheme of the invention, an original second-order cumulant-based active broadband signal separation method is extended to a fourth-order cumulant. According to the fourth-order cumulant, a corresponding duplicate vector and noise sub-space is constructed. Meanwhile, an additive noise is assumed to be a colored noise during the acoustic signal propagation process. Finally, an acoustic ray path is found out based on the orthogonality of the noise sub-space. The invention also discloses an acoustic ray propagation time tomography-based ocean acoustic tomography method and a sound source localization method. Compared with the prior art, the above method is higher in separation accuracy and can correctly separate acoustic ray paths of smaller intervals. Meanwhile, the method can be applied to conditions wherein the number of sensors is smaller than the number of ray paths. At the same time, the influence of both Gaussian noises and non-Gaussian noises can be inhibited.