176results about How to "Improve direction finding accuracy" patented technology

The invention belongs to the technical field of communication radar. An equilateral triangular array is selected as a rough measurement array in a circular array, the phase difference between two baselines in a triangular matrix is calculated, and possible actual phase differences are exhaustively listed according to the maximum ambiguity degree; the possible actual phase differences are substituted to a circular array phase difference solving formula to build a phase difference vector sample library; the ambiguity degree of the actual circular array phase difference is obtained by a related operation, and further an actual circular array phase difference vector is obtained; and finally, an incident angle value as an accurate DOA (Direction of Arrival) estimate is inversely solved by finding the least squares solution of direction cosine. The novel phase interferometer two-dimensional direction finding algorithm for ambiguity resolution by extension baselines is applied, so that higher precision can be obtained compared with a direction finding algorithm based on a related operation, and the required amount of computation is greatly reduced. The method is a high-performance angle measurement algorithm.

A method for locating partial discharge of electrical equipment is used for detecting and locating partial discharge of the electrical equipment. The technical scheme includes the steps: firstly, using three ultrasonic array sensors to receive partial discharge ultrasonic signals at different positions of the electrical equipment and forming an array model; then, converting broadband signals received by the three ultrasonic array sensors into narrow-band signals by applying a TLS (transport layer security)-based broadband focus algorithm, and obtaining azimuth information of partial discharge sources according to a narrow-band direction-finding algorithm combining the phase matching principle and cloud optimization search; and finally, determining specific positions of electrical equipment partial discharge by means of a partial discharge source location algorithm based on global optimization search of a modified genetic algorithm. The invention simultaneously provides an improved system for locating partial discharge. Compared with a traditional method for locating partial discharge, the method has the advantages of small calculation amount, high direction-finding precision, accuracy in location, high convergence rate and the like, and the system for locating partial discharge is simple in structure, low in cost and high in location precision.

The invention discloses an interferometer system based secondary surveillance radar response signal direction-finding method, which relates to the technical field of radio monitoring. The method comprises the following steps that: a 4-array-element direction-finding antenna array with a receiving sidelobe suppression antenna unit receives secondary radar response signals, and four receiving channels respectively carry out digital measuring on frequency, amplitude and phase parameters; then, an operation of controlling the receiving sidelobe suppression of an instantaneous direction-finding range and an operation of exhaustion based long-short baseline resolving phase ambiguity are performed; and finally, the orientation resolving is completed through phase orientation mapping. A secondary radar response signal direction-finding system using the method disclosed by the invention has the advantages of high direction-finding precision, rapid direction-finding speed, large instantaneous direction-finding range, low power consumption, low cost, capability of carrying out passive direction-finding, and the like, and has a good application prospect and economic benefits in promoting the air surveillance range in the field of air management and monitoring.

The invention discloses a multi-base-line phase searching type two-dimensional spatial spectrum direction-measuring method, which is based on a direction-measuring algorithm of a multi-base-line phase interferer, achieves the relation between angles specific to each base-line phase difference and a wave-coming direction, constructs a spatial spectrum function, and utilizes a two-dimensional searching method to obtain an angle of the incidence direction for direction measurement. The novel method utilizing the phase interferer method to measure the direction can directly perform two-dimensional searching by constructing the spatial spectrum function to obtain the direction of an incidence signal under the condition that each base-line phase difference is unknown. The multi-base-line phase searching type two-dimensional spatial spectrum direction-measuring method can achieve two-dimensional measurement of the incidence directions including multi-source and multi-path signals and effectively avoid the condition of failure of the direction-measurement method caused by an amplitude-phase error of each channel.

The invention relates to a communication signal processing technology, in particular to a quick direction finding method for a correlation interferometer. The quick direction finding method for a correlation interferometer comprises the following steps of: (1) firstly, calculating multichannel steering vectors corresponding to 0-180 DEG azimuth angle and each elevation angle according to an angle interval required by a direction finding user, normalizing the steering vectors by taking one channel as a reference, and storing the normalization result; (2) receiving multichannel external wireless signals, and performing orthogonal digital down conversion on each channel wireless signal to obtain a low intermediate frequency complex signal or zero intermediate frequency complex signal; and (3) normalizing the obtained low intermediate frequency complex signal or zero intermediate frequency complex signal according to the reference used by the steering vectors, calculating the coefficient of correlation between the complex signal and a prestored steering vector in each direction, and determining the direction of an external wireless signal according to the coefficient of correlation. With the quick direction finding method, the direction of a spatial signal can be obtained through fewer calculations under the condition of not changing array compositions. The quick direction finding method has fewer calculation steps, easiness in realization and high direction finding accuracy.

The invention discloses a satellite-borne three-array-element monopulse two-dimensional direction finding method. The satellite-borne three-array-element monopulse two-dimensional direction finding method comprises the following steps: firstly, maximum baseline limit is calculated according to the minimum wavelength of received signals and the amplitude comparison angle measurement accuracy, the minimum baseline length requirement is calculated according to the required angle measurement accuracy and the maximum wavelength of the received signals, the maximum and minimum baseline requirementsare compared, and the length of baselines is determined; an amplitude difference tablet and a phase difference tablet which correspond to incident signals in different directions are calculated according to the antenna interval, the antenna wave beam directional angle and an amplitude and phase directional diagram; then the amplitude difference of the same signal is received through three array elements to be related to the amplitude difference tablet, and rough finding values of the signal incident directions are obtained; and finally, the search range of the signal incident directions is determined through the rough finding result and direction finding accuracy of amplitude comparison direction finding, the phase differences between three channels are related to the phase difference tablet to be interpolated, and then the fine finding angle result is obtained. By decreasing the number of the array elements and the system channels and the quantity of system equipment, the direction finding accuracy of a satellite-borne warning system is effectively improved.

The invention discloses a phase difference direction finding and spatial spectrum direction finding combined direction-finding positioning system. Direction-finding positioning is carried out aiming at radio-frequency signals received by a N-element uniform circular array, wherein N refers to an odd number larger than or equal to 5; two parallel baseline groups in the circular array are selected to acquire N-1 array element pairs, and each array element pair corresponds to one phase discriminator; the radio-frequency signals received by the nth array element are received by a nth receiving channel and enter a signal-to-noise-ratio estimator through a nth analog-digital converter to realize signal-to-noise-ratio estimation; the signal-to-noise-ratio estimator leads out N output ends; each output end generates a first branch and a second branch, each output end is connected with one of the branches each time, each first branch is connected to a spatial spectrum beam former, and each second branch is connected to the phase discriminator corresponding to the array element of the radio-frequency signals; an output end of each phase discriminator is connected to a spatial phase interferometer. By combination of the two incompatible methods including phase difference direction finding and spatial spectrum direction finding, high-precision combined direction-finding positioning can be realized on a same platform.

The invention discloses a spare double parallel linear array and a two-dimensional DOA (Direction of Arrival) estimation method. The linear array comprises two SULAs with the difference between array element numbers to be one; the sub array with the larger array element number also comprises an auxiliary array element with the distance with the original point to be smaller than or equal to 0.5 lambda; the gap between the SULA array elements is lambda; and the gap between the sub arrays is 0.5 lambda. The corresponding DOA estimation method comprises steps: a linear transformation matrix is obtained based on an autocorrelation matrix for received data, and based on unit arrays with the same dimensions and the same signal number, a propagation matrix Pc is constructed; through carrying out vertical partitioning and corresponding matrix transformation on the Pc, the cosines of included angles between incident signals and the y axis are solved; based on a total array flow matrix corresponding to the two SULAs, two groups of cosines of included angles between incident signals and the x axis are solved; deblurring is carried out based on the received data of the auxiliary array element; and by using the cosines of the included angles between the incident signals and the x axis and the y axis, estimation values of an elevation angle and an azimuth angle are solved. The spare double parallel linear array and the two-dimensional DOA direction estimation method are used for wireless communication, the structure is simple, the cost is low, and the direction-finding precision is high.

The invention provides an ADS-B ground station having a monopulse direction finding function. The ADS-B ground station comprises four directional antennas, four radio frequency transceiver assemblies and a ground station host, wherein the four directional antennas are respectively arranged in four directions of 0 DEG, 90 DGE, 180 DEG and 270 DEG, the four radio frequency transceiver assemblies are used for receiving radio frequency signals inducted by the directional antennas and sending the received signals to the ground station host, the ground station host is used for selecting the first strongest one and the second strongest one of the four paths of radio frequency signals to carry out differential calculation to acquire the angle information of sending parties of the radio frequency signals; if the radio frequency signals are response signals of A / C mode query signals, the distance information of the sending parties of the radio frequency signals are acquired according to the sending time of the A / C mode query signals and the reception time of the response signals; and the angle information and the distance information are integrated to generate the monitoring information. According to the ADS-B ground station, a signal amplitude comparison method is utilized to accomplish direction finding of an aircraft, distance finding is accomplished according to the receiving / sending signal time difference, and thereby positioning of the aircraft is accomplished.

The invention discloses an acoustic vector array wideband direction finding method based on a sparse decomposition theory, and relates to a direction finding technique and implementation method for target broadband continuous spectrum noise in the acoustic vector sensor array detection field. The sparsification idea is introduced to an acoustic vector array direction finding system; a combined sparse constraint is established according to frequency point components in broadband continuous spectrum noise signal bandwidth; and finally, a unified airspace sparse decomposition form is obtained, thereby realizing direction finding of the broadband continuous spectrum noise. According to the method, a relatively-sharp spectrum peak and a low-amplitude noise floor can be formed; when the number of array snapshots is small, the method is stable in performance and can distinguish coherent signal sources; and when the target DOA (direction of arrival) approaches to the array axial direction, the phenomenon of noise floor fluctuations occurring under the condition of low signal-to-noise ratio of a conventional beam forming (CBF) method and a minimum variance distortionless response (MVDR) method does not exist.

The invention discloses a two-stage MUSIC microphone array direction finding method. The method includes the steps that a microphone array which is composed of N array elements receives spatial far field sound source signals, and sampled data of the microphone array are acquired; the sampled data are segmented to acquire segmented microphone array data; frequency domain segmented array data are acquired; available frequency units are selected, so that an available frequency set is obtained; the reference frequency is determined when the angle of arrival is estimated; the two-stage MUSIC algorithm is used for calculating the angle of incidence of the sound source signals. According to the method, the advantages of the frequency units at different frequency bands in the angle estimating process are combined, the frequency unit which is closest to the reference frequency is selected to be subjected to two-stage MUSIC spectrum estimation at most, the frequency units at the high frequency stage are used for guaranteeing the angle estimating precision, the frequency units at the low frequency stage are used for solving the angle estimating blur, the angle estimating result at the low frequency stage is used for solving the angle blur at the high frequency stage, and therefore a high-precision angle estimating result can be acquired.

The invention provides a coherent signal DOA (Direction-of-Arrival) estimation method based on sparse Bayesian learning. The method comprises the following steps that: obtaining the output signal of areceiving array, carrying out meshing on an observation space, constructing a super complete array manifold, combining with a sparse representation thought to convert a DOA estimation problem into aspare signal reconstruction problem, solving the following sparse matrix equations, establishing a spare Bayesian probability model, adopting a variation Bayesian deduction method to calculate the approximate posterior distribution of each hidden variable, and calculating the DOA estimation value of an incidence signal. By use of the estimation method, the number of incidence signals does not needto be estimated in advance, the estimation method does not relate to a decorrelation operation, the DOA estimation of a coherent signal is effectively realized, and the DOA estimation method which isput forward has good angle resolving power by aiming at the coherent signal. Compared with other existing DOA estimation methods, the method exhibits better direction-finding accuracy.

The invention discloses a target direction-finding method based on an acoustic vector two-dimensional nested array, and is used for direction and pitching measurement of an underwater target. The method includes building a new acoustic vector two-dimensional nested array which is formed by two two-dimensional acoustic vector subarrays nested in geometric position, array elements of the subarray 1 are distributed in sparse grids, array elements of the subarray 2 are distributed in dense grids, two grids can be selected arbitrarily, that a matrix that associate the grids is an integer matrix is required only, the integer matrix can also be selected freely, then an autocorrelation matrix of signals output by the array are utilized to build a difference synthesis acoustic vector two-dimensional array, and finally a three-dimensional smooth DOA algorithm is utilized to obtain second-order statistics of received signals of the difference synthesis acoustic vector array.

The invention discloses a Doppler direction finder based on a four-dimensional antenna array. The Doppler direction finder comprises a transceiving antenna array, a high-speed RF switch which is connected with easy array element, a complex programmable logic device, and a backend signal generating and processing device. Phase center movement occurs when the four-directional antenna array performs receiving. Different Doppler frequencies are generated for echo signals in different directions. Through extracting the Doppler frequency, direction of an object can be found. Furthermore in signal receiving, the number of antenna conducting units can be changed in real time. In operation of a direction finding system, the number of the conducting units in signal receiving can be changed, and furthermore a direction finding range and a direction finding precision are adjusted. The Doppler direction finder based on the four-dimensional antenna array has advantages of simple structure, high flexibility in use, and high suitability for different direction finding requirements.

The invention discloses a method for estimating incoming wave directions of targets in radar based on external illuminators by the aid of a GPU (graphics processing unit). The method mainly solves problems that the traditional method for estimating incoming wave directions of targets is constrained by signal processing platforms and algorithms and the requirement on instantaneity cannot be met. The technical scheme includes that the method comprises performing time-domain interference cancellation and range-Doppler two-dimensional correlation processing on unit data and then loading the unit data into a GPU-based computing system on the basis of an idea of compressed sensing; creating a sensing matrix; sparsely reconstructing and solving azimuth on the basis of compressed sensing in the GPU by a parallel process according to the processed unit data and the sensing matrix; acquiring solved azimuth signal vectors; reconstructing the incoming wave directions of the targets by the aid of the azimuth signal vectors. The method has the advantages of simplicity in building hardware platforms, good stability, high computation speed and expandability and easiness in development, and is applicable to estimating incoming wave directions of multiple targets in radar based on external illuminators.

The invention discloses a method and a device for correcting direction finding accuracy of an ultra-wideband multi-beam system. The method comprises: testing the intermediate beam of the system usinga microwave darkroom planar test system, and recording the planar near-field test data; obtaining the amplitude phase distribution information of an antenna unit aperture field according to the inversion of the obtained planar near-field test data; determining whether the error of the amplitude phase distribution information of the antenna aperture field and the theoretical value satisfies the requirement; testing all beams and full bands of the system using the microwave darkroom planar test system; writing the direction finding table into the system according to the far field pattern of theobtained planar near-field data inversion system; and inputting the calculated code value to obtain the correction parameters for each channel after the beam correction compensation is completed. Themethod and device have simple and convenient engineering implementation, can improve the direction finding accuracy of the system, especially in the case that the target frequency deviates from the center frequency and the target bearing deviates from the intermediate beam, which is beneficial to the subsequent target tracking processing.

The invention discloses a method and system for constructing a four-element three-dimensional array. The method comprises the following steps of: arbitrarily rotating a three-dimensional rectangular coordinate system where a traditional three-element planar array is located by an angle, adding a non-coplanar fourth element to construct a preliminary four-element three-dimensional array; calculating the phase differences of the other three elements relative to the first element at different time; creating a direction finding model according to the calculated phase differences of the other three elements relative to the first element; calculating a direction-finding error between the estimated value and the actual value of the to-be-measured wave direction by using the direction finding model; selecting a plurality of fourth elements with different rotation angles, calculating the direction-finding precision of the to-be-measured wave direction in a desired pitch angle area, determining the rotation angle corresponding to the calculated highest direction-finding precision as a best rotation angle, and constructing the final four-element three-dimensional array according to the best rotation angle. The four-element three-dimensional array constructed by using the method is capable of improving the direction finding precision in a small pitch angle area.

The invention discloses an optimal arrangement method of an UHF phased array used for substation partial discharge direction finding. The optimal arrangement method comprises the steps of: 1) making a number of array elements and array element spacing of the phased array unchanged, deriving Cramer-Rao low bound expressions in different geometric shapes, and optimizing a geometric shape of the UHF phased array; 2) making array element spacing of the phased array after geometric shape optimization unchanged, drawing a relation curve between direction finding errors and the number of array elements in numerical simulation, and optimizing the number of array elements of the UHF phased array by combining with a construction cost of an acquisition system; 3) and acquiring partial discharge signals in a substation for the phased array after geometric shape and array element number optimization, analyzing frequency spectra of the signals, and optimizing array element spacing of the UHF phased array. The optimal arrangement method adopts the UHF phased array which is small in size, has the advantages of high anti-interference ability and high spatial resolution, and is convenient for partial discharge patrol inspection.

The present invention discloses an ultrashort-wave single-channel direction-finder antenna array. The objective of the invention is to provide a multi-platform and foldable single-channel direction-finder antenna array with frequencies capable of covering an ultrashort-wave range. The technical scheme of implementation method comprises the following steps that: each of antennas with two frequencyranges outputs 2-5 paths of radio frequency signals to a radio frequency switch matrix, the radio frequency switch matrix switches low and high frequency ranges through a radio frequency switch to 2-5power divider input terminals, and selects and inputs an antenna with a low frequency range or an antenna with a high frequency range at the same time to the power divider input terminals, signals output by the radio frequency switch in each path are divided into two paths by the power dividers, four phase shifters are output in one path, input and output terminals of the phase shifters are switched by the radio frequency switch, signals in one path are output to a combiner 2; signals in the other path are output to a combiner 1, the 2-5 paths of antenna signals are combined into one omnidirectional reference signal which is transmitted into the phase shifter and the combiner 2, and the combiner 2 combines the output signals of the phase shifter and the output signals of the combiner 1 into single-channel radio frequency signals.

The invention discloses a space frequency two-dimensional spectrum estimation method based on a compressed sampling array, which mainly solves a problem that data storage is enabled to become extremely difficult because a surprising amount of data in conditions of a high sampling rate and multiple channels. Implementation of the method comprises the steps of 1) using signals acquired by receives of N1 antennas to act as an input signal matrix X; 2) generating an observation matrix Y according to the input signal matrix X; 3) constructing frequency domain basis matrix F, and setting a time domain compression matrix Phib and joint sparse matrix Zf according to the observation matrix Y, and establishing a signal model Y<T>=PhibFZf; 4) solving the signal model so as to acquire the joint sparse matrix Zf, and acquiring a non-zero support set Gamma according the joint sparse matrix; and 5) solving a space frequency two-dimensional spectrum Zp according to the non-zero support set Gamma. The method disclosed by the invention reduce the number of channels and the time domain sampling rate of the system, improves the transient signal receiving bandwidth and the direction finding precision, and can be applied to a radar and reconnaissance integration system.

The invention provides an improved short-wave unit positioning method, and aims to provide a positioning method with the advantages of high-resolution positioning performance, small calculation amount, and high estimation precision. The improved short-wave unit positioning method is implemented by the steps of: acquiring a beam domain covariance matrix through solving an autocorrelation matrix based on beam domain output data; calculating eigenvalues and corresponding eigenvectors of the beam domain covariance matrix through decomposition, judging whether a signal source number exits, and determining signal source subspaces and noise subspaces corresponding to the signal source number, so as to obtain estimated values for automatic pairing of signal sources; then constructing a polynomialf(z) and solving roots of the polynomial f(z); solving a root high resolution spectrum, solving roots (on an approaching unit circle) of which the number is the same as that of dimension numbers of the signal subspaces, combining with array element data, beam number and corresponding physical parameters, performing external radiation signal source direction-of-arrival estimation, acquiring eigenvectors of the signal source number, performing deep learning, and adjusting positioning precision of a short-wave single station automatically.

The invention relates to a design method of an array structure for direction of arrival estimation. The layout of a non-equidistant array is realized through optimizing an array element position. The design method comprises the following several steps: determining minimum array element spacing d<min>, a maximum array element position d<max> and the quantity N of used array elements; calculating an array adjustable array laying-out distance D which is equal to d<max>-(N-1)d<min>; optimally designing an array which is represented by a performance parameter G and a side lobe or a grating lobe height; and outputting an existing optimal result, and the like. By using the design method, through an optimization design, under the condition that the array element spacing is guaranteed to be not less than some specific value, a direction-finding array reaches the optimization between the direction-finding precision and a spatial spectral pseudo peak height; a proper array designed by adopting the method can synchronously realize a lower spatial spectral pseudo peak and the higher direction-finding precision under the condition of fewer array elements; the array element spacing can be enabled to break through half-wavelength limitation, thereby reducing the mutual coupling effect between the array elements and improving the direction-finding precision; a certain space is also preserved for enlarging the apertures of the array elements to detect a weaker signal; and an effective optimization design method is provided.

The invention provides a direction-finding method and device for single-transmission double-receiving passive radar, belongs to the technical field of radar, and is tended to solve the problem that fixed object direct-finding technique has high cost with safety easily threatened. The method comprises: setting a first receiver, a second receiver and a transmitter in a two-dimensional plane, and cycling the first receiver and the second receiver respectively around an origin; through equation (1), determining a transmitter, a direction-finding model of a first single-transmission single-receiving observation passage formed by the first receiver and a fixed target, and a direction-finding model of a second single-transmission single-receiving observation passage; normalizing first and second direction-finding results of the direction-finding model of the first single-transmission single-receiving observing passage respectively to obtain a frequency-domain direction-finding equation of the fixed target in the first single-transmitting single-receiving observation passage, and a frequency-domain direction-finding equation of the fixed target in the second single-transmitting single-receiving observation passage; through equation (2), acquiring direction-finding results of the fixed target.

The invention relates to a stereo array antenna based on double directed circular arrays and a construction method of the antenna. The stereo array antenna comprises two identical planar circular arrays, each planar circular array comprises array elements, an adjustable included angle gamma is formed between the planes of the two circular arrays, an intersecting line between the planes of the twocircular arrays does not pass the center of any an array element of the two circular arrays, the array elements of the two circular arrays are distributed symmetrically by taking the intersecting lineas the center, and the distance from the circular center of each circular array to the intersecting line is d; and the included angle gamma is determined according to the relation between a direction-finding error in a theoretical direction of arrival and the included angle gamma. A construction method of the stereo array antenna comprises the steps of establishing a coordinate system, establishing a direction finding model, establishing a direction finding error model and determining the stereo array antenna. The stereo array antenna is constructed on the basis of a narrow wave beam directedarray, and the direction finding precision in specific low-elevation-angle area is improved effectively on the basis that the direction finding precision in a traditional five-element circular arraylarge-elevation-angle area is not reduced.

The invention discloses a digital intermediate frequency single pulse orientation method. The method is implemented on the basis of a receiver of an onboard anti-collision system, an antenna of the onboard anti-collision system is the antenna of a four-radar unit, and the four-radar unit is arranged squarely. The method comprises the following steps of: (1) sampling bandpass; (2) performing digital phase discrimination; (3) automatically calibrating phase differences; and (4) mapping phase orientation. By the method, the onboard anti-collision system has correct orientation, high speed, small volume, low power consumption and low cost, has obvious advantages in market competition and can produce high economic benefits.

The invention discloses an airborne single baseline Doppler-phase difference direction finding method by which an entire cycle solution of a radial distance can be directly obtained through comprehensively utilizing the relation among a speed vector equation, a Doppler frequency shift and a change rate, therefore, an entire cycle value of a path difference between radial distances of two adjacent array elements of single baseline can be obtained. The path difference is entirely determined after the value of a non-entire cycle part of the path difference is determined by further utilizing a phase difference. Hence, under the condition that the length of the baseline is determined, the direction of an object can be directly obtained according to a trigonometric function relationship. The invention has a series of advantages of low installation requirement, short measuring time, suitability for bandwidth detection, and the like.

The invention provides the orthogonal propagation operator direction finding method based on a multi-peak quantum cuckoo search mechanism. The method comprises the following steps of through samplingdata, acquiring the estimation values of a covariance matrix and a propagation operator; initializing parameters and quantum bird eggs, and calculating the fitness of the mapped bird eggs; initializing a memory pool; using Levy flight to update the quantum bird eggs and calculating the fitness of the mapped bird eggs; using a memory operator to update the memory pool; using a selection operator toselect; renewing new nests to update the quantum bird eggs and calculating the fitness of mapped bird eggs; using the memory operator to update the memory pool; using the selection operator to select; determining whether to reach a current phase iteration number; if the current phase iteration number is reached, using a purification operator to delete a similar memory element and entering into anext phase; and determining whether to reach a maximum iteration number: if the maximum iteration number is not reached, continuously carrying out iteration; otherwise, outputting all the quantum birdeggs in the memory pool, after mapping, defining as a wave reaching direction. The method possesses advantages that an operation amount is low, a convergence speed is fast and direction finding precision is high.

The invention discloses a passive radar fixed target frequency domain direction-finding method based on an external radiation source. The passive radar fixed target frequency domain direction-finding method comprises the steps of establishing a direction-finding system model; deducing a slant range progress of a single-scattering-point target; deducing a demodulated single-scattering-point target echo signal model and performing variable substitution for obtaining a frequency domain expression; expanding the frequency domain expression of the single-scattering-point target echo signal to a multi-target condition, modifying a target scattering strength function, and obtaining a relationship between the frequency domain expression of a multi-target echo signal and the modified target strength function; and calculating the direction of each target by means of a polar coordinate algorithm. The passive radar fixed target frequency domain direction-finding method is realized based on a narrow-band external radiation source signal in a two-dimensional space; the polar coordinate algorithm is used; and convolution operation is performed. The convolution operation can be processed through fast Fourier transform and inverse transformation, thereby greatly reducing calculation amount of the algorithm, realizing high robustness, obtaining relatively high direction finding precision and simultaneously finding a plurality of target directions in an observing area.

The invention discloses a sparse array design method used for azimuth and pitching two-dimensional direction-finding. The sparse array design method comprises steps of establishment of a coordinate system, array deployment design, array manifold, and a weighting method. The sparse array design method is advantageous in that a number of channels under the condition of the same antenna aperture is less; under the condition of the same aperture, N is an array element number of routinely uniformly arranged array antennas in one dimension, and the number of the antenna channels is N2; by adopting the sparse design, the number of the two-dimensional direction-finding antenna channels is still N; by adopting the sparse array design method, costs of improving the direction-finding precision are greatly reduced, system complexity is low, and costs are reduced.

The invention discloses a novel portable five-antenna-element direction-finding circular array and aims at providing a five-antenna-element direction-finding circular array which is small in volume, light in weight and capable of being disassembled rapidly and meeting demands of a plurality of kinds of direction-finding systems such as interferometers, correlation interferometers and space spectrum estimators and the like at the same time. The five-antenna-element direction-finding circular array includes a circular-array body, support arms and oscillators. The circular-array body is provided with high-end antenna elements and low-end support arm installation holes. The five non-removable high-end antenna elements are uniformly installed at an upper part, a center shaft being the axis. An electronic compass is installed in a cavity of the upper part. Five low-end support arm installation holes are uniformly distributed at a middle part, the center shaft being the axis. The low-end support arm installation holes are provided with double-screw bolts. One end of each support arm is provided with a threaded sleeve. The double-screw bolts are connected with the threaded sleeves. Two oscillators are installed in the vertical direction of the other end of each support arm so that the five low-end antenna elements are formed.