Target two-dimensional angle positioning method, device, radar and storage medium

Abstract

The present invention relates to a method, device, computer equipment and storage medium for two-dimensional angle positioning of a target. The method comprises the following steps: transmitting a signal to a target through a radar transmitter mounted on a rotating platform, and receiving a reception signal reflected by the target through a radar receiver; performing phase compensation according to reception signals of a one-dimensional linear coprime array at different times; determining an equivalent reception signal vector of an extended virtual two-dimensional non-parallel linear array, selecting a uniform two-dimensional non-parallel linear array without holes to determine a uniform reception signal vector, and determining an equivalent reception signal equivalent steering vector of a two-dimensional array based on the uniform reception signal vector; constructing an angle spectrum and a least squares problem according to the two-dimensional uniform reception signal vector and the equivalent steering vector, solving a two-dimensional angle of target pairing, and determining the target position.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a target two-dimensional angle positioning method, device, radar and storage medium. Background Art

[0002] Radars usually locate multiple long-range targets in three-dimensional space by measuring two-dimensional (2-D) angular parameters. In order to achieve 2D Direction Of Arrival (DoA) estimation, various 2D geometric arrays have been designed. Among them, L-type and V-type arrays can be regarded as two non-parallel uniform linear arrays connected at one end, and are widely used due to their simple structure and superior performance. In order to increase the achievable degrees of freedom (DoF) given a fixed number of physical array elements, researchers have proposed to use coprime linear arrays (CLA) to construct coprime L-shaped arrays. On the other hand, the prototype CLA can be installed on a mobile platform with a constant speed to achieve an increase in the degree of freedom. If the array environment remains stationary for a period of time during the movement, continuous sampling on the path of the array's linear motion, analyzing and integrating the sampled data at different times can expand the size of the virtual array and further increase the degree of freedom. In addition to linear motion, rotational motion based on sparse circular arrays has also been studied, and it has been verified that this scheme can effectively increase the degree of freedom.

[0003] We propose a 2D DoA estimation scheme that utilizes a 1D linear coprime array mounted on a rotating platform to increase the total number of virtual domain elements. By exploiting the information of different array positions during the rotation duration, a general framework for synthesizing 2D coprime arrays is proposed to unify some commonly used 2D array structures. L-shaped and V-shaped arrays can be generated by designing appropriate rotation angular velocities. The resulting covariance matrix is ​​vectorized to obtain a virtual differential coarray with a larger continuous span. 2D DoA estimation is achieved by applying a 2D Multiple Signal classification (MUSIC) algorithm to the resulting co-array signals. The effectiveness of the proposed framework is verified using extensive numerical simulations. Summary of the invention

[0004] Based on this, it is necessary to provide a two-dimensional angle positioning method, device, radar and storage medium for the target that can break through the one-dimensional linear array estimation dimension to address the above technical problems.

[0005] A target two-dimensional angle positioning method of the present invention specifically includes the following steps:

[0006] Step 1: transmit a signal to the target through the transmitter of the local radar mounted on the rotating platform, and receive the received signal reflected by the target through the one-dimensional linear coprime array of the receiver of the local radar;

[0007] Step 2, according to the received signals of the one-dimensional linear coprime array of the receiver at the initial sampling time t and the current time t+τ, compensate the phase difference caused by the delay between the transmitted signal at the sampling time t+τ and the initial sampling time t;

[0008] Step 3, determining an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to received signals of the one-dimensional linear coprime array at different times, wherein the extended virtual two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes;

[0009] Step 4, selecting a uniform two-dimensional non-parallel linear array without holes to determine a uniform received signal vector, and determining an equivalent received signal equivalent steering vector of the two-dimensional array based on the uniform received signal vector;

[0010] Step 5, constructing an angle spectrum and a least squares problem based on the two-dimensional uniform received signal vector and the equivalent steering vector, solving the paired two-dimensional target angle, and determining the target position.

[0011] Further, in step 2, according to the received signals of the one-dimensional linear coprime array of the receiver at the initial sampling time t and the current time t+τ, the phase difference caused by the delay between the transmitted signal at the sampling time t+τ and the initial sampling time t is compensated, which specifically includes the following steps:

[0012] Step 2.1, establishing a coprime array model according to the coprime structure information of the one-dimensional linear coprime array of the receiver; the coprime array model includes two uniform sparse subarrays, namely a first subarray and a second subarray; the array element spacing between the first subarray and the second subarray is a pair of coprime numbers;

[0013] Step 2.2, determining the one-dimensional linear coprime array received signal vector at time t according to the received signal of the one-dimensional linear coprime array mounted on the rotating platform and the coprime array model mounted on the rotating platform;

[0014] According to the one-dimensional linear coprime array receiving signal, frequency diversity model and coprime array model, it is assumed that there are Q unrelated far-field targets, and the qth (q=1,2,…Q)th target is located in (θ q ,φ q ) position, where θ q and φ q Respectively represent the azimuth and elevation angles of the qth target;

[0015] The angular velocity of the rotating platform is Ω, from which the position of the array element is defined as:

[0016]

[0017] Among them, y l ,z l represents the position of the lth array element in the Cartesian coordinate system, u l Represents the distance between the first and lth elements in a one-dimensional linear coprime array.

[0018] Assume that the 2D DoA of the target relative to the array remains constant during a very short rotational motion period; corresponding to time t = 1, 2, …, T s The received signal is expressed as:

[0019]

[0020] where s q (t) represents the complex scattering coefficient, c is the propagation speed of light, T s represents the number of snapshots, ε(t) represents additive white Gaussian noise, and

[0021]

[0022]

[0023] The received signal vector is expressed as

[0024] s(t)=[s1(t),s2(t),…s Q (t)] T . (33)

[0025] Step 2.3, determining the received signal vector of the one-dimensional linear coprime array at time t+τ according to the received signals of the one-dimensional linear coprime array carried on the rotating platform at different times and the coprime array model carried on the rotating platform;

[0026] The array element based on the rotating platform at time t+τ is expressed as:

[0027]

[0028] Since the position of the array and the frequency offset change over time, at time t+τ, the output of the receiving array is expressed as:

[0029]

[0030] in

[0031] B=[b(θ1,φ q ),b(θ2,φ q ),…,b(θQ ,φ Q )], (36)

[0032]

[0033] For example, Ωτ=π / 2 is selected, and the position of the one-dimensional linear coprime array based on the rotating platform is expressed as:

[0034]

[0035] The one-dimensional linear coprime array received signal vector at time t+τ is expressed as

[0036]

[0037] Step 2.4, Phase Compensation

[0038] The received signal after compensation is expressed as

[0039]

[0040] in, is the noise after phase compensation

[0041]

[0042] Then the received signals of the one-dimensional linear coprime array at time t and time t+τ are written as:

[0043]

[0044] Furthermore, in step 3, according to the received signals of the one-dimensional linear coprime array at different times, determining the equivalent received signal vector of the extended virtual two-dimensional non-parallel linear array specifically includes the following steps:

[0045] Step 3.1, constructing a two-dimensional non-parallel linear coprime array model according to the received signals of the one-dimensional linear coprime array at different times after the phase compensation;

[0046] Step 3.2, determining an equivalent steering vector of an equivalent received signal of a two-dimensional non-parallel linear coprime array according to received signals of the one-dimensional linear coprime array at different times;

[0047] Step 3.3, respectively determine the covariance matrix of the two-dimensional linear coprime array of the two-dimensional non-parallel linear coprime array; written as:

[0048]

[0049]

[0050] Among them, R ss=diag{p1,…,p Q}, p q represents the scattered power of the qth target; represents the power of Gaussian noise;

[0051] Step 3.5, respectively performing vectorization operations on the covariance matrices of the two-dimensional linear coprime arrays to obtain equivalent received signal vectors of the extended two-dimensional non-parallel linear arrays; specifically as follows:

[0052] Using T s snapshots to replace the estimated covariance matrix, namely:

[0053]

[0054]

[0055] Vectorizing the covariance matrix to obtain an extended virtual two-dimensional non-parallel linear equivalent received signal vector, wherein the equivalent received signal vector includes the extended virtual two-dimensional non-parallel linear steering vector;

[0056] In this step, the extended virtual two-dimensional non-parallel linear equivalent received signal vector is obtained by vectorizing the covariance matrix respectively:

[0057]

[0058]

[0059] Where p=[p1,p2,…p Q ] T represents the target scattered power,

[0060]

[0061] Furthermore, in step 4, a uniform two-dimensional non-parallel linear array without holes is selected to determine a uniform received signal vector, and based on the uniform received signal vector, an equivalent received signal equivalent steering vector of the two-dimensional array is determined respectively.

[0062] Step 4.1, selecting a uniform virtual two-dimensional non-parallel linear portion without holes in the extended virtual two-dimensional non-parallel linear array, and respectively determining a non-negative received signal vector of a non-negative region of a two-dimensional linear uniform array in the extended virtual two-dimensional non-parallel linear array;

[0063] Step 4.2, determining two non-negative covariance matrices of the corresponding two-dimensional linear uniform array of the receiver respectively according to the non-negative received signal vector;

[0064] Step 4.3, vectorize the two non-negative covariance matrices respectively to obtain two equivalent received signal vectors and two equivalent steering vectors of a non-negative equivalent virtual array corresponding to a two-dimensional linear uniform array.

[0065] Furthermore, in step 5, according to the two-dimensional uniform received signal vector and the equivalent steering vector, an angle spectrum and a least squares problem are constructed to solve the paired two-dimensional target angle and determine the target position, as follows:

[0066] Virtual signal x v and is equivalent to a single snapshot signal with rank loss due to coherence, so spatial smoothing is required to recover y v The rank of the covariance matrix of ; then, the MUSIC algorithm is directly applied to the smoothed signal to estimate the angles of all targets separately, which is expressed as

[0067]

[0068]

[0069] in, represents the noise subspace of the spatially smoothed covariance matrix, the vector represents the steering vector of the virtual signal, then the relationship between the estimated angle and the target angle is written as:

[0070]

[0071]

[0072] In order to obtain paired estimation results, the cross-covariance matrix of the two parts of the two-dimensional non-parallel array is used to perform accurate two-dimensional DoA estimation; using the transformation in formula (33) (34), the pitch angle is estimated

[0073] To obtain the paired direction angles The cross covariance matrix is ​​calculated as

[0074] Now the goal is to estimate the steering matrix B, whose columns correspond to the estimated steering matrix This process will produce an automatically paired azimuth and elevation estimate; thus, the following least squares problem is solved, namely,

[0075]

[0076] in, In practical applications, we get the cross covariance matrix as Next, we use the MUSIC algorithm to estimate the direction angle, and the angle It is estimated by the following formula:

[0077]

[0078] in, yes The noise subspace eigenvector matrix, angle After determination, the direction angle θ can be obtained by the formula Find out.

[0079] Furthermore, the rotating platform performs uniform rotational motion, the motion direction is clockwise, and the angular velocity of the rotating platform is constant and known;

[0080] The target should be a far-field target, and the target is considered to be stationary at different sampling moments, and the relative position of the target and the rotating platform is fixed.

[0081] A target two-dimensional angle positioning device comprises: a signal transceiver module, which is used to transmit a signal to a target through a transmitter of a local radar mounted on a rotating platform, and receive a reception signal reflected by the target through a receiver of the local radar;

[0082] A phase compensation module, which compensates for the phase difference between the transmitted signal at the current sampling moment and the initial sampling moment due to the delay according to the delay between the current moment and the initial moment and the frequency of the transmitted signal;

[0083] A two-dimensional virtual array extension module, which determines an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to received signals of the one-dimensional linear coprime array at different times after the phase compensation, wherein the extended two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes;

[0084] An equivalent received signal construction module selects a uniform two-dimensional non-parallel linear uniform array without holes to determine a uniform received signal vector, and based on the uniform received signal vector, determines an equivalent received signal equivalent steering vector of the two-dimensional linear uniform array respectively;

[0085] The target positioning module constructs an angle spectrum and a least squares problem according to the two-dimensional uniform received signal vector and the equivalent steering vector, solves the paired two-dimensional target angle, and determines the target position.

[0086] A radar comprises a transmitter, a receiver and a processor, wherein the transmitter mounted on a rotating platform and the receiver mounted on the rotating platform are respectively connected to the processor, the transmitter mounted on the rotating platform is used to transmit a signal; the receiver mounted on the rotating platform comprises a one-dimensional linear coprime array, each array element of the coprime array is used to receive a received signal formed by a target reflecting the transmitted signal; the processor is used to perform the following steps: transmitting a signal to a target through a radar transmitter mounted on the rotating platform at this end, and receiving the received signal reflected by the target through a receiver of the radar at this end; performing phase compensation according to the received signals of the one-dimensional linear coprime array at different times; determining an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to the received signals of the one-dimensional linear coprime array at different times after the phase compensation, wherein the extended two-dimensional non-parallel linear array comprises holes and a uniform virtual two-dimensional non-parallel linear array without holes;

[0087] A uniform two-dimensional non-parallel linear uniform array without holes is selected to determine a uniform received signal vector, and based on the uniform received signal vector, equivalent steering vectors of equivalent received signals of the two-dimensional linear uniform array are respectively determined; according to two received signal vectors of the two-dimensional linear uniform array corresponding to the two-dimensional non-parallel linear array, estimated values ​​of covariance matrices corresponding to the two uniform received signals are respectively calculated; eigenvalue decomposition is performed on the estimated values ​​of the two covariance matrices respectively to extract noise subspaces; according to the corresponding two-dimensional uniform equivalent received signal equivalent steering vectors and their corresponding noise subspaces, , calculate and obtain two one-dimensional angle spectra; respectively identify the two one-dimensional angle spectra, determine the highest spectrum peak of the angle spectrum, and respectively calculate two related angles corresponding to the highest spectrum peak; according to the two related angle values, calculate and obtain the target pitch angle value; according to the equivalent steering vector of the two-dimensional uniform equivalent received signal vector, calculate and obtain the mutual correlation matrix of the two-dimensional signal, and establish a least squares problem to solve and obtain the azimuth angle value paired with the pitch angle; according to the pitch angle value and the paired azimuth angle value, determine the position of the target terminal.

[0088] A computer-readable storage medium stores a computer program, which implements the following steps when executed by a processor: transmitting a signal to a target through a radar transmitter mounted on a rotating platform at this end, and receiving a received signal reflected by the target through a receiver of the radar at this end; performing phase compensation according to the received signals of the one-dimensional linear coprime array at different times; determining an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to the received signals of the one-dimensional linear coprime array at different times after the phase compensation, wherein the extended two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes; selecting a uniform two-dimensional non-parallel linear array without holes to determine a uniform received signal vector, and determining an equivalent received signal equivalent steering vector of a two-dimensional array based on the uniform received signal vector; constructing an angle spectrum and a least squares problem according to the two-dimensional uniform received signal vector and the equivalent steering vector, solving the paired two-dimensional target angle, and determining the target position.

[0089] Beneficial effects: The above-mentioned two-dimensional target angle positioning method, device, radar and storage medium expand the received signal of the one-dimensional linear coprime array reflected by the target to an extended virtual two-dimensional non-parallel linear array, and the number of array elements in the obtained extended virtual two-dimensional non-parallel linear array is greater than the number of array elements in the actual physical array. In addition, by mounting the radar on a rotating platform, the received signal information at multiple array element positions at different times can be jointly processed through phase compensation, and two-dimensional angle estimation can be achieved using only a one-dimensional linear coprime array. More importantly, a general framework for synthesizing two-dimensional coprime arrays is proposed, which can unify some commonly used two-dimensional array structures. At the same time, this scheme further increases the number of virtual array elements and fills the holes in the virtual array, so that the dimension of the final solution exceeds the dimension provided by the actual received signal, thereby effectively improving the degree of freedom of the two-dimensional angle estimation of the target. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 is an application environment diagram of a two-dimensional angle positioning method for a target in an embodiment;

[0091] Figure 2 is a schematic diagram of a flow chart of a two-dimensional angle positioning method of a target in an embodiment;

[0092] Figure 3 is a schematic diagram of a one-dimensional linear coprime array model mounted on a rotating platform in one embodiment;

[0093] Figure 4 is a schematic diagram of synthesizing L-shaped and V-shaped physical arrays in one embodiment;

[0094] Figure 5is a schematic diagram of an extended virtual L-shaped and X-shaped array corresponding to a composite L-shaped and V-shaped physical array in one embodiment;

[0095] Figure 6 is a graph of SNR-angle RMSE in a single target embodiment;

[0096] Figure 7 is a snapshot number-angle RMSE curve graph in a single target embodiment;

[0097] Figure 8 is a graph of SNR-angle RMSE in a multi-objective embodiment;

[0098] Fig. 9 is a snapshot number-angle RMSE curve graph in a multi-objective embodiment;

[0099] Fig.10 is a structural block diagram of a two-dimensional angle positioning device for a target in an embodiment;

[0100] Fig.11 It is a schematic diagram of the structure of a radar in an embodiment.

[0101] Among them, 100, radar; 101, processor; 102, transmitter; 103, receiver; 104, far-field target; 105, one-dimensional linear coprime array; 700, target two-dimensional angle positioning device; 701, signal transceiver module; 702, phase compensation module; 703, two-dimensional virtual array expansion module; 704, equivalent received signal construction module; 705, target positioning module. DETAILED DESCRIPTION

[0102] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0103] The target two-dimensional angle positioning method provided by the present invention can be applied to Figure 1 In the application environment shown in the figure, the radar 100 has a transmitter 102 and a receiver 103, both of which are arranged on a rotating platform. The radar 100 can transmit a signal to a far-field target 104 around the radar 100 through the transmitter 102 mounted on the rotating platform, and can receive a received signal reflected by the target through the receiver 103 at the local end. The radar 100 performs the target two-dimensional angle positioning method of each embodiment of the present invention on the far-field target 104 to position the two-dimensional angle of the far-field target 104.

[0104] Embodiment 1

[0105] like Figure 2 As shown, a two-dimensional angle positioning method for a target is provided, and the method is applied to Figure 1 The radar in FIG. 1 is taken as an example to illustrate the method, which includes the following steps.

[0106] Step 1: transmit a signal to the target through the transmitter 102 of the local radar mounted on the rotating platform, and receive the received signal reflected by the target through the one-dimensional linear coprime array 105 of the receiver 103 of the local radar.

[0107] Step 2, based on the received signals of the one-dimensional linear coprime array 105 of the receiver 103 at the initial sampling time t and the current time t+τ, compensate the phase difference caused by the delay between the transmitted signal at the sampling time t+τ and the initial sampling time t. Specifically, the following steps are included:

[0108] Step 2.1, establishing a coprime array model according to the coprime structure information of the one-dimensional linear coprime array 105 of the receiver 103;

[0109] The mutually prime array model includes two uniform sparse subarrays, namely a first subarray and a second subarray. Figure 3 shown.

[0110] The total number of elements in the first subarray is 2M, and the element spacing is Nd. The total number of elements in the second subarray is N, and the element spacing is Md, where d is the unit distance. The first elements of the two subarrays can share the same element, so the total number of physical elements in the coprime array is 2M+N-1. Where d=λ / 2 represents the unit element spacing, and λ represents the wavelength. The expression of the coprime number set corresponding to the elements of the two subarrays is as follows:

[0111]

[0112] in, represents the set of coprime numbers of the first subarray elements, represents a set of coprime numbers of the second subarray elements.

[0113] Step 2.2, determining the received signal vector of the one-dimensional linear coprime array 105 at time t according to the received signal of the one-dimensional linear coprime array 105 mounted on the rotating platform and the coprime array model mounted on the rotating platform;

[0114] According to the one-dimensional linear coprime array 105 receiving signal, frequency diversity model and coprime array model, it is assumed that there are Q unrelated far-field targets 104, and the qth (q=1, 2, ... Q)th target is located in (θ q ,φ q ) position, where θ q and φ qrepresent the azimuth and elevation angles of the qth target respectively.

[0115] The angular velocity of the rotating platform is Ω, from which the position of the array element can be defined as:

[0116]

[0117] Among them, y l ,z l represents the position of the lth array element in the Cartesian coordinate system, u l Represents the distance between the lth array element and the lth array element in a one-dimensional linear coprime array.

[0118] Assume that the 2D DoA of the target relative to the array remains constant during a very short rotational motion period. Corresponding to time t = 1, 2, ..., T s The received signal can be expressed as:

[0119]

[0120] where s q (t) represents the complex scattering coefficient, c is the propagation speed of light, T s represents the number of snapshots, ε(t) represents additive white Gaussian noise, and

[0121]

[0122]

[0123] The received signal vector is expressed as

[0124] s(t)=[s1(t),s2(t),…s Q (t)] T . (62)

[0125] Step 2.3, determining the received signal vector of the one-dimensional linear coprime array 105 at time t+τ according to the received signals of the one-dimensional linear coprime array 105 mounted on the rotating platform at different times and the coprime array model mounted on the rotating platform;

[0126] The array element based on the rotating platform at time t+τ can be expressed as:

[0127]

[0128] Since the position of the array and the frequency offset change over time, at time t+τ, the output of the receiving array is expressed as:

[0129]

[0130] in

[0131] B=[b(θ1,φ q ),b(θ2,φ q ),…,b(θ Q ,φ Q )], (65)

[0132]

[0133] For example, if Ωτ=π / 2 is selected, the position of the one-dimensional linear coprime array 105 based on the rotating platform can be expressed as:

[0134]

[0135] The one-dimensional linear coprime array 105 receiving signal vector at time t+τ is expressed as

[0136]

[0137] Therefore, combining the signal vectors at time t and time t+τ, we get the synthetic L-type array model. Without loss of generality, we take t = 0. The signal vector of the synthetic L-type array can be written as:

[0138]

[0139]

[0140] Taking M=3 and N=5 as an example, the L-type coprime array model determined by steps 2.1-2.3 is as follows: Figure 4 (a) shown.

[0141] For example, the design of the V-type array includes determining the array element position according to the coprime sampling characteristic and determining the V angle of coupling between the azimuth angle and the elevation angle estimation. for For a certain value of , the azimuth and elevation estimation problems are decoupled. To obtain decoupled DoA estimates, the cross terms of the Fisher information matrix need to be zero. This condition can be satisfied by setting the V angle size of the two-dimensional array element, using To represent the number of elements in the virtual V-shaped array, It can be expressed as:

[0142]

[0143] When M=3 and N=5, choose The position of the one-dimensional linear coprime array 105 based on the rotating platform at time t and time t+τ can be expressed as:

[0144]

[0145]

[0146] Therefore, combining the signal vectors at time t and time t+τ, we can get the synthetic V-array model. The signal vector of the synthetic V-array can be written as:

[0147]

[0148]

[0149] Taking M=3 and N=5 as an example, the V-type coprime array model determined by steps 2.1-2.3 is as follows: Figure 4 (b) as shown.

[0150] Step 2.4, phase compensation;

[0151] In order to simultaneously process the received signals at time t and time t+τ, it is necessary to compensate the phase correction factor to generate a phase-synchronized received signal vector. The compensated received signal is expressed as

[0152]

[0153] in, is the noise after phase compensation

[0154]

[0155] Then the received signals of the one-dimensional linear coprime array 105 at time t and time t+τ are written as:

[0156]

[0157] Step 3: after phase compensation, determining an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to received signals of the one-dimensional linear coprime array 105 at different times, wherein the extended virtual two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes;

[0158] Taking M=3 and N=5 as an example, the extended virtual two-dimensional non-parallel linear Figure 5 As shown, the extended virtual two-dimensional non-parallel linear model contains the information of the coprime array model on the rotating platform.

[0159] Step 3.1: construct a two-dimensional non-parallel linear coprime array model according to the received signals of the one-dimensional linear coprime array 105 at different times after the phase compensation.

[0160] Step 3.2: Determine an equivalent steering vector of an equivalent received signal of a two-dimensional non-parallel linear coprime array according to received signals of the one-dimensional linear coprime array 105 at different times;

[0161] Step 3.3: Determine the covariance matrix of the two-dimensional linear coprime arrays of the two-dimensional non-parallel linear coprime arrays respectively; write it as:

[0162]

[0163]

[0164] Among them, R ss =diag{p1,…,p Q}, p q represents the scattered power of the qth target. represents the power of Gaussian noise.

[0165] Step 3.5: performing vectorization operations on the covariance matrices of the two-dimensional linear coprime arrays to obtain equivalent received signal vectors of the extended two-dimensional non-parallel linear arrays; specifically as follows:

[0166] Since the frequency separation is smaller than the carrier frequency, it can be approximately considered that the scattering coefficient of each target is independent of the carrier frequency. s snapshots to replace the estimated covariance matrix, namely:

[0167]

[0168]

[0169] The covariance matrix is ​​vectorized to obtain an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear system, wherein the equivalent received signal vector includes a steering vector of the extended virtual two-dimensional non-parallel linear system; the extended virtual two-dimensional non-parallel linear system (i.e., a non-uniform virtual two-dimensional non-parallel linear system) includes holes and uniform virtual two-dimensional non-parallel linear systems without holes.

[0170] For example, in this step, by vectorizing the covariance matrix respectively, an extended virtual two-dimensional non-parallel linear equivalent received signal vector can be obtained:

[0171]

[0172]

[0173] Where p=[p1,p2,…p Q ] T represents the target scattered power,

[0174]

[0175] Figure 5 Indicates the corresponding Figure 4 2D virtual domain array element.

[0176] Step 4: Select a uniform two-dimensional non-parallel linear array without holes to determine a uniform received signal vector, and determine the equivalent received signal equivalent steering vector of the two-dimensional array based on the uniform received signal vector.

[0177] Step 4.1: Select a uniform virtual two-dimensional non-parallel linear portion without holes in the extended virtual two-dimensional non-parallel linear array, and respectively determine a non-negative received signal vector of a non-negative region of a two-dimensional linear uniform array in the extended virtual two-dimensional non-parallel linear array;

[0178] Step 4.2: Determine two non-negative covariance matrices of the corresponding two-dimensional linear uniform array of the receiver 103 according to the non-negative received signal vector;

[0179] Step 4.3: Vectorize the two non-negative covariance matrices respectively to obtain two equivalent received signal vectors and two equivalent steering vectors of a non-negative equivalent virtual array corresponding to a two-dimensional linear uniform array.

[0180] Step 5: Based on the two-dimensional uniform received signal vector and the equivalent steering vector, construct an angle spectrum and a least squares problem, solve the paired two-dimensional target angle, and determine the target position.

[0181] For example, the virtual signal x v and is equivalent to a single snapshot signal with rank loss due to coherence, so spatial smoothing is required to recover y v The rank of the covariance matrix of . Subsequently, the MUSIC algorithm can be directly applied to the smoothed signal to estimate the angles of all targets separately, which is expressed as

[0182]

[0183]

[0184] in, represents the noise subspace of the spatially smoothed covariance matrix, the vector represents the steering vector of the virtual signal, then the relationship between the above estimated angle and the target angle can be written as:

[0185]

[0186]

[0187] In order to obtain paired estimation results, the cross-covariance matrix of the two parts of the two-dimensional non-parallel array is used to perform accurate two-dimensional DoA estimation. Using the transformation in formula (33) (34), the pitch angle can be estimated To obtain the paired direction angles The cross covariance matrix is ​​calculated as

[0188] Now our goal is to estimate the steering matrix B, whose columns correspond to the estimated steering matrix This process will produce an automatically paired azimuth and elevation estimate. Therefore, we solve the following least squares problem, namely,

[0189]

[0190] in, In practical applications, we get the cross covariance matrix as Next, we use the MUSIC algorithm to estimate the direction angle, and the angle It can be estimated by the following formula:

[0191]

[0192] in, yes The noise subspace eigenvector matrix, angle After being determined, the direction angle θ can be obtained by the angle Deduced.

[0193] In the target two-dimensional angle positioning method of each of the above embodiments of the present invention, the technology of coprime sampling is introduced, and the concept of coprime two-dimensional non-parallel linear array is proposed. The coprime two-dimensional non-parallel linear array uses the concept of differential common array to circumvent the limitation of physical sampling. Nevertheless, the obtained virtual frequency-controlled array contains holes. In order to make full use of the array aperture and the degrees of freedom of the virtual frequency-controlled array, the present invention further expands the position of the holes, mounts the radar on a rotating platform, and combines the received signals sampled at different times to expand the degrees of freedom.

[0194] It should be understood that although Figure 2 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 2 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0195] Simulation experiment

[0196] The present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation examples. It should be pointed out that this specific implementation example does not have a limiting effect and is only used to verify the validity of the invention.

[0197] The present invention proposes a two-dimensional angle estimation method for a one-dimensional linear coprime array 105 on a rotating platform. In order to verify the performance advantage of the algorithm, an example process of the present invention is given below.

[0198] (1) Simulation experiment parameter setting

[0199] In this section, extensive numerical simulations are used to evaluate the 2D DoA estimation performance of the proposed rotated 1D linear coprime array 105. The performance of L-type coprime array and V-type coprime array without rotation are studied using coprime pairs M=3, N=5 to verify the effectiveness of the proposed scheme.

[0200] (2) Comparison of single target estimation performance

[0201] Consider a far-field target 104 located at (sinθ, sinφ) = (0.4, 0.2). We first fix the number of snapshots to 500 and the signal-to-noise ratio to vary between -10dB and 14dB. The RMS error curve of the angle estimation is shown in Figure 6 We observe that the RMSE of DoA estimation using the proposed scheme is slightly worse than that of the conventional 2D coprime array, but the proposed method uses only half of the physical array elements, and the estimation accuracy obtained by simulation is acceptable. If we instead vary the number of snapshots and fix the input SNR to 0dB, we obtain Figure 7 Similarly, the performance of the proposed method is close to that of the traditional two-dimensional coprime array in terms of RMSE. In the single target scenario, the above results have demonstrated the effectiveness of the proposed method in terms of degrees of freedom and estimation accuracy.

[0202] (3) Comparison of multi-objective estimation performance

[0203] Consider further the case where there are 9 unrelated targets. We assume that the sine values ​​of the azimuth and elevation angles are uniformly distributed in the nine values ​​between [-0.5, 0.5]. Similarly, Figure 8 The performance of 2-D DoA estimation with varying input SNR is compared, where the number of snapshots is fixed to 500. The RMSE of all methods decreases with increasing SNR, while the proposed scheme achieves similar estimation performance to the conventional 2D coprime array using only half of the array elements. Next, we compare the performance of the estimation scheme with varying number of snapshots, where the input SNR is set to 0dB. Fig. 9 As shown, the numerical results once again confirm the effectiveness of the proposed estimation framework.

[0204] The above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0205] Embodiment 2

[0206] like Fig.10 As shown, a target two-dimensional angle positioning device 700 is provided, comprising: a signal transceiver module 701, a phase compensation module 702, a two-dimensional virtual array expansion module 703, an equivalent received signal construction module 704 and a target positioning module 705, wherein:

[0207] The signal transceiver module 701 is used to transmit a signal to a target through a transmitter 102 of a local radar mounted on a rotating platform, and receive a received signal reflected by the target through a receiver 103 of the local radar;

[0208] The phase compensation module 702 compensates the phase difference caused by the delay between the transmitted signal at the current sampling moment and the initial sampling moment according to the delay between the current moment and the initial moment and the frequency of the transmitted signal;

[0209] The two-dimensional virtual array extension module 703 determines an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to the received signals of the one-dimensional linear coprime array 105 at different times after the phase compensation, wherein the extended virtual two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes;

[0210] The equivalent received signal construction module 704 selects a uniform two-dimensional non-parallel linear uniform array without holes to determine a uniform received signal vector, and based on the uniform received signal vector, determines the equivalent received signal equivalent steering vectors of the two-dimensional linear uniform array respectively;

[0211] The target positioning module 705 constructs an angle spectrum and a least squares problem according to the two-dimensional uniform received signal vector and the equivalent steering vector, solves the paired two-dimensional target angle, and determines the target position.

[0212] For the specific definition of the target two-dimensional angle positioning device 700, please refer to the definition of the target two-dimensional angle positioning method above, which will not be repeated here. The various modules of the above-mentioned target two-dimensional angle positioning device 700 can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0213] Embodiment 3

[0214] like Fig.11 As shown, a radar 100 mounted on a rotating platform is provided, including a transmitter 102, a receiver 103 and a processor 101, wherein the transmitter 102 and the receiver 103 are respectively connected to the processor 101, and the transmitter 102 is used to transmit a signal;

[0215] The receiver 103 includes a one-dimensional linear coprime array 105, each array element of the one-dimensional linear coprime array 105 is used to receive a received signal formed by a far-field target 104 reflecting a signal;

[0216] Specifically, in one embodiment, the one-dimensional linear coprime array 105 of the receiver 103 includes a first subarray and a second subarray, a plurality of array elements (antennas) in the first subarray are uniformly arranged at a first array element interval, a plurality of array elements in the second subarray are uniformly arranged at a second array element interval, the first array element interval is not equal to the second array element interval, the first array elements of the first subarray and the second subarray may share the same array element, and a plurality of array elements of the first subarray and a plurality of array elements of the second subarray are arranged in an array together to form the one-dimensional linear coprime array 105, so that the one-dimensional linear coprime array 105 has a coprime structure.

[0217] The processor 101 is used to perform the following steps:

[0218] Step 1, transmitting a signal to a far-field target 104 through a transmitter 102 of a local radar 100 mounted on a rotating platform, and receiving a reception signal reflected by the far-field target 104 through a receiver 103 of the local radar 100;

[0219] Step 2, based on the received signals of the one-dimensional linear coprime array 105 of the receiver 103 at the initial sampling time t and the current time t+τ, compensate the phase difference caused by the delay between the transmitted signal at the sampling time t+τ and the initial sampling time t;

[0220] Step 3, determining an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to received signals of the one-dimensional linear coprime array at different times after phase compensation, wherein the extended virtual two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes;

[0221] Step 4, selecting a uniform two-dimensional non-parallel linear array without holes to determine a uniform received signal vector, and determining an equivalent received signal equivalent steering vector of the two-dimensional array based on the uniform received signal vector;

[0222] Step 5, constructing an angle spectrum and a least squares problem based on the two-dimensional uniform received signal vector and the equivalent steering vector, solving the two-dimensional target angle of the target 104 pairing, and determining the position of the target 104.

[0223] In other embodiments, the processor 101 further executes the steps of the target two-dimensional angle positioning method of any of the above embodiments.

[0224] Those skilled in the art will understand that Fig.11 The structure shown in the figure is only a block diagram of a part of the structure related to the scheme of the present invention, and does not constitute a limitation on the radar to which the scheme of the present invention is applied. The specific radar may include more or less components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0225] In one embodiment, a computer readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0226] Step 1, transmitting a signal to a target through a radar transmitter 102 mounted on a rotating platform at the local end, and receiving a reception signal reflected by the target through a receiver 103 of the radar at the local end;

[0227] Step 2, based on the received signals of the one-dimensional linear coprime array of the receiver 103 at the initial sampling time t and the current time t+t, compensate the phase difference caused by the delay between the transmitted signal at the sampling time t+τ and the initial sampling time t;

[0228] Step 3, determining an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to received signals of the one-dimensional linear coprime array at different times after the phase compensation, wherein the extended two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes;

[0229] Step 4, selecting a uniform two-dimensional non-parallel linear array without holes to determine a uniform received signal vector, and determining an equivalent received signal equivalent steering vector of the two-dimensional array based on the uniform received signal vector;

[0230] Step 5, constructing an angle spectrum and a least squares problem based on the two-dimensional uniform received signal vector and the equivalent steering vector, solving the paired two-dimensional target angle, and determining the target position.

[0231] In other embodiments, when the computer program is executed by the processor 101, the steps of the target two-dimensional angle positioning method in any of the above embodiments are also implemented.

[0232] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0233] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0234] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A target two-dimensional angle positioning method, characterized in that: The specific steps include: Step 1: transmit a signal to the target through the transmitter of the local radar mounted on the rotating platform, and receive the received signal reflected by the target through the one-dimensional linear coprime array of the receiver of the local radar; Step 2, according to the received signals of the one-dimensional linear coprime array of the receiver at the initial sampling time t and the current time t+τ, compensate the phase difference caused by the delay between the transmitted signal at the sampling time t+τ and the initial sampling time t; Step 3, determining an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to received signals of the one-dimensional linear coprime array at different times, wherein the extended virtual two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes; Step 4, selecting a uniform two-dimensional non-parallel linear array without holes to determine a uniform received signal vector, and determining an equivalent received signal equivalent steering vector of the two-dimensional array based on the uniform received signal vector; Step 5, constructing an angle spectrum and a least squares problem according to the two-dimensional uniform received signal vector and the equivalent steering vector, solving the paired two-dimensional target angle, and determining the target position; In step 2, according to the received signals of the one-dimensional linear coprime array of the receiver at the initial sampling time t and the current time t+τ, the phase difference caused by the delay between the transmitted signal at the sampling time t+τ and the initial sampling time t is compensated, which specifically includes the following steps: Step 2.1, establishing a coprime array model according to coprime structure information of a one-dimensional linear coprime array of a receiver; the coprime array model includes two uniform sparse subarrays, namely a first subarray and a second subarray; Step 2.2, determining the one-dimensional linear coprime array received signal vector at time t according to the received signal of the one-dimensional linear coprime array mounted on the rotating platform and the coprime array model mounted on the rotating platform; According to the one-dimensional linear coprime array receiving signal, frequency diversity model and coprime array model, it is assumed that there are Q unrelated far-field targets, and the qth target is located in the two-dimensional polar coordinate system (θ q ,φ q ) position, q = 1, 2, ... Q, where θ q and φ q Respectively represent the azimuth and elevation angles of the qth target; The angular velocity of the rotating platform is Ω, from which the position of the array element is defined as: Among them, y l ,z l represents the position of the lth array element in the Cartesian coordinate system, u l Represents the distance between the first array element and the lth array element in a one-dimensional linear coprime array; Assume that the 2D DoA of the target relative to the array remains constant during a very short rotational motion period; corresponding to time t = 1, 2, ..., T s The received signal is expressed as: where s q (t) represents the complex scattering coefficient, c is the propagation speed of light, T s represents the number of snapshots, ε(t) represents additive white Gaussian noise, and The received signal vector is expressed as s(t)=[s1(t),s2(t),...s Q (t)] T (5) Step 2.3, determining the received signal vector of the one-dimensional linear coprime array at time t+τ according to the received signals of the one-dimensional linear coprime array carried on the rotating platform at different times and the coprime array model carried on the rotating platform; The array element based on the rotating platform at time t+τ is expressed as: Since the position of the array and the frequency offset change over time, at time t+τ, the output of the receiving array is expressed as: in B=[b(θ1,φ q ),b(θ2,φ q ),...,b(θ Q ,f Q )], (8) s(t)=[s1(t+τ),s2(t+τ),...s Q (t+τ)] T (10) Select Ωτ=π / 2, and the position of the one-dimensional linear coprime array based on the rotating platform is expressed as: The one-dimensional linear coprime array received signal vector at time t+τ is expressed as Step 2.4, Phase Compensation The received signal after compensation is expressed as in, is the noise after phase compensation Then the received signals of the one-dimensional linear coprime array at time t and time t+τ are written as: In step 3, according to the received signals of the one-dimensional linear coprime array at different times, an equivalent received signal vector of the extended virtual two-dimensional non-parallel linear array is determined, which specifically includes the following steps: Step 3.1, constructing a two-dimensional non-parallel linear coprime array model according to the received signals of the one-dimensional linear coprime array at different times after the phase compensation; Step 3.2, determining an equivalent steering vector of an equivalent received signal of a two-dimensional non-parallel linear coprime array according to received signals of the one-dimensional linear coprime array at different times; Step 3.3, respectively determine the covariance matrix of the two-dimensional linear coprime array of the two-dimensional non-parallel linear coprime array; written as: Among them, R ss =diag{p1,...,p Q }, p q represents the scattered power of the qth target; represents the power of Gaussian noise; Step 3.4, respectively performing vectorization operations on the covariance matrices of the two-dimensional linear coprime arrays to obtain equivalent received signal vectors of the extended two-dimensional non-parallel linear arrays; specifically as follows: Using T s snapshots to replace the estimated covariance matrix, namely: Vectorizing the covariance matrix to obtain an extended virtual two-dimensional non-parallel linear equivalent received signal vector, wherein the equivalent received signal vector includes the extended virtual two-dimensional non-parallel linear steering vector; In this step, the extended virtual two-dimensional non-parallel linear equivalent received signal vector is obtained by vectorizing the covariance matrix respectively: Where p=[p1,p2,...p Q ] T represents the target scattered power, In step 4, a uniform two-dimensional non-parallel linear array without holes is selected to determine a uniform received signal vector, and based on the uniform received signal vector, an equivalent received signal equivalent steering vector of the two-dimensional array is determined respectively. Step 4.1, selecting a uniform virtual two-dimensional non-parallel linear portion without holes in the extended virtual two-dimensional non-parallel linear array, and respectively determining a non-negative received signal vector of a non-negative region of a two-dimensional linear uniform array in the extended virtual two-dimensional non-parallel linear array; Step 4.2, determining two non-negative covariance matrices of the corresponding two-dimensional linear uniform array of the receiver respectively according to the non-negative received signal vector; Step 4.3, vectorizing the two non-negative covariance matrices respectively to obtain two equivalent received signal vectors and two equivalent steering vectors of a non-negative equivalent virtual array corresponding to a two-dimensional linear uniform array; In step 5, according to the two-dimensional uniform received signal vector and the equivalent steering vector, an angle spectrum and a least squares problem are constructed to solve the paired two-dimensional target angle and determine the target position, as follows: Virtual signal x v and is equivalent to a single snapshot signal with rank loss due to coherence, so spatial smoothing is required to recover y v The rank of the covariance matrix of ; then, the MUSIC algorithm is directly applied to the smoothed signal to estimate the angles of all targets separately, which is expressed as in, represents the noise subspace of the spatially smoothed covariance matrix, the vector represents the steering vector of the virtual signal, then the relationship between the estimated angle and the target angle is written as: In order to obtain paired estimation results, the cross-covariance matrix of the two parts of the two-dimensional non-parallel array is used to perform accurate two-dimensional DoA estimation; using the transformation in formula (25) (26), the pitch angle is estimated To obtain the paired direction angles The cross covariance matrix is ​​calculated as Now the goal is to estimate the steering matrix B, whose columns correspond to the estimated steering matrix This process will produce an automatically paired azimuth and elevation estimate; thus, the following least squares problem is solved, namely, in, In practical applications, we get the cross covariance matrix as Next, we use the MUSIC algorithm to estimate the direction angle, and the angle It is estimated by the following formula: in, yes The noise subspace eigenvector matrix of angle After determination, the direction angle θ can be obtained by the formula Find out.

2. A target two-dimensional angle positioning method according to claim 1, characterized in that: The rotating platform performs uniform rotational motion in a clockwise direction, and the angular velocity of the rotating platform is constant and known; The target should be a far-field target, and the target is considered to be stationary at different sampling moments, and the relative position of the target and the rotating platform is fixed.

3. A device using the target two-dimensional angle positioning method as claimed in claim 1, characterized in that: The device comprises: A signal transceiver module, used to transmit a signal to a target through a transmitter of a local radar mounted on a rotating platform, and receive a reception signal reflected by the target through a receiver of the local radar; A phase compensation module, which compensates for the phase difference between the transmitted signal at the current sampling moment and the initial sampling moment due to the delay according to the delay between the current moment and the initial moment and the frequency of the transmitted signal; A two-dimensional virtual array extension module, which determines an equivalent received signal vector of an extended virtual two-dimensional non-parallel linear array according to received signals of the one-dimensional linear coprime array at different times after the phase compensation, wherein the extended virtual two-dimensional non-parallel linear array includes holes and a uniform virtual two-dimensional non-parallel linear array without holes; An equivalent received signal construction module selects a uniform two-dimensional non-parallel linear uniform array without holes to determine a uniform received signal vector, and based on the uniform received signal vector, determines an equivalent received signal equivalent steering vector of the two-dimensional linear uniform array respectively; The target positioning module constructs an angle spectrum and a least squares problem according to the two-dimensional uniform received signal vector and the equivalent steering vector, solves the paired two-dimensional target angle, and determines the target position.

4. A radar, comprising a transmitter, a receiver and a processor, wherein the transmitter and the receiver are connected to the processor respectively, characterized in that: The transmitter is used to transmit a signal; The receiver comprises a one-dimensional linear coprime array mounted on a rotating platform, each array element of the coprime array being used to receive a received signal formed by a target reflecting the transmitted signal; The processor is configured to execute the steps of the method according to any one of claims 1 to 2.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 2 are implemented.

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