30results about How to "Improve angle estimation accuracy" patented technology

Methods and transducers for producing acoustical signals having a spiral wavefront with omnidirectional magnitude and a phase that varies with angle and transducers for producing broadband omnidirectional reference signals for underwater navigation and communication.

The invention discloses a method for MIMO radar system angle estimation based on fast Fourier transformation. The method for MIMO radar system angle estimation based on fast Fourier transformation comprises the steps that a data matrix received by a first pulse of the radar system is evenly divided and divided signals are expressed in the description, new signals are divided by the four matrix blocks defining; bi-dimensional fast Fourier transformation is respectively conducted to the signals shown in the description; coherent integration is conducted on F11(l), F12(l), F21(l) and F22(l), a peak point shown in the description and the corresponding subscript ix and the corresponding subscript iy are recorded, points corresponding to the subscript ix and the subscript iy are respectively obtained from the F11(l), the F12(l), the F21(l) and the F22(l), so that the vector of f(1) belonging to C4*1 is established; the covariance matrix of the f(1) is calculated according to the sampling covariance matrix inversion principle, characteristic decomposition is conducted on the covariance matrix, and a noise projection matrix pn can be obtained through a noise sub space un; a transmitting oriented vector and a receiving oriented vector br(theta) are obtained according to a receiving data matrix Y(1) and the leaving angle and the reaching angle are estimated through the MUSIC arithmetic.

The invention belongs to the technical field of estimation of the direction of arrival of radar and discloses a low-altitude target direction-of-arrival estimating method for radar. The low-altitude target direction-of-arrival estimating method for the radar comprises the steps that an antenna array of the radar receives echo signals, the echo signals are sampled to obtain a data vector matrix, singular value decomposition is conducted on the data vector matrix to enable a corresponding dimensionality-reduction data vector and a corresponding noise subspace matrix to be generated, a guide vector matrix is obtained, a corresponding multi-path attenuation vector is obtained according to the noise subspace matrix and the guide vector matrix, a composite guide vector is constructed, a sensing matrix is constructed, a regularization parameter is obtained, and the direction of arrival is obtained by solving a corresponding mathematical model.

The invention relates to the technical field of radar signal processing and discloses an angle-measuring and identifying method for target and bait interferences in a main lobe of monopulse radar. The method comprises the following steps: with an improved radar receiver, extracting an echo signal of an opposite angle difference channel and judging if bait interference exists; with single target angle measurement and single pulse angle measurement for target and bait, identifying true and false target angles; and controlling an angle tracking gate of the monopulse radar according to the angle measurement output of a true target. According to the angle-measuring and identifying method provided by the invention, the receiver is used for extracting a double-difference signal and processing the signal, so as to realize the angle position estimation for two undistinguishable targets, complete bait interference detection and true target identification, increase the interference detection and identification accuracy and calculation efficiency and enhance the instantaneity of interference detection. The angle-measuring and identifying method provided by the invention has important practical significance in increasing the angle distinguishing capability of monopulse radar and improving existing target indication radar and tracking guidance radar and terminal guidance radar.

The invention discloses a broadband frequency agility angle super resolution method using prior information. The problem that elevation estimation is low in precision in a sea surface multipath environment in the prior art is mainly solved. The implementation steps are as follows: 1) a radar receives echoes of different carrier frequencies and acquires a sample data vector of the different carrier frequencies; 2) the sample data vector is used for calculating a sampling covariance matrix of all frequency points and calculating a multi-frequency combined sampling covariance matrix; 3) a sea surface parameter is used for estimating a sea surface reflection coefficient; 4) an echo path difference corresponding to a search angle is calculated; 5) the reflection coefficient and the path difference are used for acquiring the synthetic steering vector of all the frequency points; 6) the synthetic steering vector is used for constituting a multi-frequency combined projection matrix; and 7) the multi-frequency combined sampling covariance matrix and the multi-frequency combined projection matrix are used for conducting one dimensional search to obtain a target angle. The broadband frequency agility angle super resolution method using the prior information improves the angle resolution power of a radar to low altitude targets, and can be used for estimating the direction of wave arrival in a multipath environment of a shipbased radar.

The invention discloses a sight angle estimation method based on a human eye difference image, and the method comprises the steps: inputting two different human eye images: a tested human eye image and a reference human eye image into a twin neural network, and obtaining a difference value of a corresponding sight angle through network regression; when the sight angle of the reference human eye image is known, the sight angle of the tested human eye image can be obtained. The method solves the problem that in an existing sight line angle estimation method, the sight line angle is directly estimated from an image, and large estimation errors are caused by personal apparent differences. Meanwhile, the problem that the workload of data calibration for a certain individual is quite large is solved. According to the method, the difference value of the sight angles in the two images is estimated by using the twin neural network technology, so that the sight angle of the tested human eye image is obtained, the angle estimation precision is high, and the robustness is good.

The invention belongs to the technical field of radar, and discloses an angle estimation method based on a 2q-order nested MIMO array structure. The method comprises the following steps of: S1, designing a 2q-order nested MIMO array structure; S2, calculating 2q-order cumulants of received signals according to the 2q-order nested MIMO array, and arranging the 2q-order cumulants to obtain a 2q-order cumulant matrix; S3, constructing a 2q-order sum-difference joint array based on the 2q-order cumulant matrix; S4, constructing an average value C'of a covariance matrix according to the 2q-order sum-difference joint array; and S5, estimating the DOA based on the average value C'of the covariance matrix by adopting a multi-signal classification MUSIC algorithm or a signal parameter ESPRIT algorithm based on a rotation invariant technology. Therefore, the estimation method can further improve the degree of freedom while suppressing Gaussian color noise, and improve the estimation precision and the estimable target number.

A single-bit spatial spectrum estimation method based on logistic regression relates to a spatial spectrum estimation field in array signal processing and a logistic regression field in artificial intelligence. The single-bit spatial spectrum estimation method settles problems of high calculation amount and relatively low precision in a traditional spatial spectrum algorithm on the condition of single-bit extreme quantification and ultralarge-scale antenna array. According to the method of the invention, single-bit received data are modeled for obtaining a sample model, and furthermore an observation model is converted to a real number domain for facilitating subsequent processing. After modeling, a spatial spectrum is used as a coefficient of a linear classifier; a flow pattern is used as an input sample; an array observation output is used as the output which corresponds with the input sample; and spatial spectrum estimation is converted to a linear classification problem. According to the algorithm of the invention, the linear classification problem is solved by means of a logistic regression, thereby obtaining a classification coefficient and a spatial spectrum which is generated correspondingly with an array input signal. The single-bit spatial spectrum estimation method is mainly used for spatial spectrum estimation.

A steering system includes a housing, a steering operation shaft that is housed in the housing and configured to move in an axial direction to steer right and left steered wheels, a first drive source that generates a first drive force, a second drive source that generates a second drive force, a first power transfer unit that applies an axial force to the steering operation shaft with the first drive source, a second power transfer unit that applies an axial force to the steering operation shaft with the second drive force, a position detection sensor that is provided in the housing and detects an axial position of the steering operation shaft, and a control device that controls the first drive source and the second drive source using a detection result of the position detection sensor.

The invention discloses a reference period signal carrier frequency offset elimination method and system based on Bluetooth fixed frequency expansion, which are applied to a Bluetooth wireless communication system. The method comprises the following steps: establishing synchronous connection between a Bluetooth receiving end with a receiving antenna array and a Bluetooth transmitting end, and adding compensation to sampling data by calculating a difference value between a phase difference between fixed-frequency extension reference period signal sampling points in a received Bluetooth signal packet and a theoretical phase difference; and eliminating a phase error caused by carrier frequency deviation due to asynchronous crystal oscillators of the receiver and the transmitter in the synchronization process. Under the working mode of single-data-channel multi-antenna time-sharing sampling, the reduction degree of the transmitted signal is improved, so that the estimation precision of the direction of arrival algorithm based on the fixed-frequency extended signal is further improved. The method is low in calculation and hardware complexity and suitable for low-power-consumption Bluetooth 5.1 and above protocols, multiple time-sharing antennas of a receiver share a single data receiving channel, and a received data packet comprises signal phase correction and restoration of a reference period.

The invention for evaluating angle of radiation source includes following steps. (1) Data acquisition is carried out in order to obtain data of power time delay distribution of radiation source. (2) Path determination is carried out so as to recognize the position and power of effective path on the power time delay distribution. (3) NLOS recognition is carried out. Using the information of position and power of the path output from step (2) recognizes whether a direct path between the radiation source and receiver is existed or not. (4) Filtering paths is carried out. (5) Based on the result recognized by NLOS and the result of filtering paths, the correspondent method for evaluating angle is determined. The invention raises the accuracy for evaluating angle of radiation source at complex geographic environment, suitable for evaluating azimuth or pitch angle.

The invention discloses a coherent signal DOA estimation method based on a co-prime array, and the method comprises the steps: firstly solving a covariance matrix of the co-prime array, carrying out the feature decomposition of the covariance matrix, and finding a feature vector corresponding to a maximum feature value; secondly, decomposing the feature vector into two parts according to the number of array elements of a co-prime array subarray, and rearranging elements of the two parts respectively to obtain two Hankel matrixes H1 and H2; thirdly, performing singular value decomposition on the H1 and the H2 to obtain noise subspaces of the H1 and the H2; and finally, on the basis of the noise subspaces of the H1 and the H2, spatial spectrums of the H1 and the H2 are drawn by applying a MUSIC method, the same spectral peak in the spatial spectrums of the H1 and the H2 is found, DOA values corresponding to the spectral peak in the spatial spectrums of the H1 and the H2 are recorded and averaged, and a final DOA estimation value is obtained. According to the method, vectorization operation does not need to be carried out on the received signals of the sparse array, the co-prime characteristic of the array can be fully utilized, the angle estimation value of the coherent signals is obtained, and the blank of coherent signal arrival angle estimation carried out by the co-prime array is filled.

The invention discloses a circular array DOA estimation method based on subspace orthogonal compensation. The method comprises the following steps: receiving a radiation source signal by an array element, and sampling the received signal; using a UCA-ESPRIT algorithm to obtain two-dimensional angle coarse estimation including an elevation angle and an azimuth angle; decomposing eigenvalues of the covariance matrix without beam conversion to obtain eigenvalues and corresponding eigenvectors, and forming a signal subspace and a noise subspace; reconstructing first-order Taylor expansion of a direction matrix based on coarse estimation by utilizing orthogonality of a steering vector and a noise subspace; obtaining an offset through a least square solution; and compensating the coarse estimation according to the offset to obtain fine estimation. The method is low in calculation complexity, solves the problem of two-dimensional angle estimation precision under the condition that the number of array elements of a circular array is small, and has important engineering application value.