Target angle and range localization methods, devices, radars, and storage media

Abstract

This invention relates to a positioning method, apparatus, computer equipment, and storage medium. The method includes: transmitting a time-modulated frequency diversity signal to a target via a radar transmitter mounted on a mobile platform, and receiving the received signal reflected from the target via a receiver of the local radar; performing phase compensation based on the time-modulated frequency diversity signal and the received signals at different times; determining an equivalent received signal vector of an extended virtual frequency diversity array based on the received signals at different times after phase compensation, wherein the extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes; selecting a uniform virtual frequency diversity array without holes to determine a uniform received signal vector; determining an equivalent received signal steering vector based on the uniform received signal vector; and constructing a range-azimuth spectrum based on the uniform received signal vector and the equivalent steering vector, and calculating and determining the target position.

Description

Technical Field

[0001] This invention relates to the field of radar technology, and in particular to a target angle and distance positioning method, device, radar, and storage medium. Background Technology

[0002] Because beam patterns are dependent on both range and angle, frequency diverse arrays (FDAs) have always been a hot research topic in radar. This unique beam pattern makes joint estimation of angle and range possible, thus enabling target localization. The degrees of freedom determine the maximum number of detectable targets, which is fundamentally limited by the number of physical array sensors and carrier waves. Coprime arrays, as a type of structured sparse array, have extended virtual column apertures. By combining coprime array structure and coprime frequency offset in frequency diverse arrays, resolution improvements can be achieved in both the angular and range domains.

[0003] To further increase the degrees of freedom, previous work investigated coprime arrays on mobile platforms. Using coprime arrays on mobile platforms allows for the collection of array-received data at different locations, and this data can be combined to generate virtual arrays with higher degrees of freedom in the angular dimension. Inspired by this approach, while employing time-varying array positions, we introduce a time-varying frequency offset. This time-modulated frequency offset further increases the degrees of freedom for joint angular-distance estimation.

[0004] In frequency diversity arrays, linear frequency modulated continuous wave (LFMCW) waveforms are used to generate time-invariant spatial focusing beammaps. Inspired by this work, we propose a joint angular distance estimation scheme that utilizes a time-modulated frequency diversity coprime array on a mobile platform, leveraging more element position and carrier frequency information within the motion cycle to locate more targets. The vectorized covariance matrix can generate a virtual difference coarray with a larger continuous span. Higher accuracy joint angular distance estimation can be achieved by employing a two-dimensional multiple signal classification (MUSIC) algorithm on the synthetic array signal. Summary of the Invention

[0005] Therefore, it is necessary to provide a target angle and distance positioning method, device, radar, and storage medium that can improve the degrees of freedom in addressing the above-mentioned technical problems.

[0006] A target angle and range localization method includes: transmitting a time-modulated frequency diversity signal to a target via a radar transmitter mounted on a mobile platform, and receiving the received signal reflected by the target via a receiver of the local radar; performing phase compensation based on the time-modulated frequency diversity signal and the received signals at different times; determining an equivalent received signal vector of an extended virtual frequency diversity array based on the received signals at different times after phase compensation, wherein the extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes; selecting a uniform virtual frequency diversity array without holes to determine a uniform received signal vector; determining an equivalent received signal steering vector based on the uniform received signal vector; and constructing a range-azimuth spectrum based on the uniform received signal vector and the equivalent steering vector, and calculating and determining the target position.

[0007] In one embodiment, the frequency offset of the frequency diversity signal has the same coprime structure as the coprime array of the receiver.

[0008] In one embodiment, the mobile platform moves at a constant linear speed in the same direction as the array, and the speed of the mobile platform is constant and known; the time-modulated frequency diversity signal adopts a linear frequency-modulated continuous wave, and the signal modulation frequency is constant and known; the target should be a far-field target, and the target is considered stationary at different sampling times, and the relative position of the target and the mobile platform is fixed.

[0009] In one embodiment, the phase difference caused by the difference between the frequency of the current time modulation frequency diversity signal and the frequency of the time modulation frequency is compensated based on the time delay between the current time and the initial time and the modulation frequency of the time modulation frequency.

[0010] In one embodiment, determining the equivalent received signal vector of the extended virtual frequency diversity array based on the frequency diversity signal and the received signal, wherein the extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes, includes: establishing a coprime array model based on the coprime structure information of the receiver's coprime array, the coprime array model consisting of two uniform sparse subarrays; establishing a frequency diversity model based on the frequency diversity information of the frequency diversity signal transmitted by the transmitter; determining the received signal vector of the coprime array based on the received signal, the frequency diversity model, and the coprime array model; determining the covariance matrix of the coprime array based on the received signal vector; vectorizing the covariance matrix to obtain the equivalent received signal vector of the extended virtual frequency diversity array, the equivalent received signal vector including the steering vector of the extended virtual frequency diversity array; the extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes.

[0011] In one embodiment, the step of selecting a hole-free uniform virtual frequency diversity array to determine a uniform received signal vector, and determining an equivalent received signal steering vector based on the uniform received signal vector, includes: selecting a hole-free uniform virtual frequency diversity array in the extended virtual frequency diversity array, determining a non-negative received signal vector in the non-negative region; determining a non-negative covariance matrix of the coprime array based on the non-negative received signal vector; vectorizing the non-negative covariance matrix to obtain a non-negative equivalent virtual array received signal vector; and determining a steering vector of the hole-free uniform virtual frequency diversity array based on the steering vector of the hole-free coprime array and the steering vector of the frequency offset of the hole-free array.

[0012] In one embodiment, constructing a range-azimuth spectrum based on the uniformly received signal vector and the equivalent steering vector, and then calculating and determining the target location, includes: calculating an estimated value of the covariance matrix corresponding to the uniformly received signal based on the uniformly received signal vector; performing eigenvalue decomposition on the estimated value of the covariance matrix to extract a noise subspace; calculating the range-azimuth spectrum based on the noise subspace and the equivalent steering vector of the equivalent received signal; identifying the highest spectral peak of the range-azimuth spectrum and calculating the distance and azimuth corresponding to the highest spectral peak; and determining the location of the target terminal based on the angle value.

[0013] A target angle and distance positioning device includes: a signal transceiver module, used to transmit a time-modulated frequency diversity signal to a target via a transmitter of a radar mounted on a mobile platform, and to receive a received signal reflected by the target via a receiver of the radar.

[0014] The phase compensation module performs phase compensation based on the time-modulated frequency diversity signal and the received signals at different times.

[0015] A virtual frequency diversity extension module is used to determine the equivalent received signal vector of the extended virtual frequency diversity array based on the frequency diversity signal and the received signal. The extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes.

[0016] The equivalent received signal construction module selects a uniform virtual frequency diversity array without holes to determine a uniform received signal vector, and determines an equivalent received signal steering vector based on the uniform received signal vector.

[0017] The target positioning module constructs a range-azimuth spectrum based on the uniformly received signal vector and the equivalent steering vector, and calculates and determines the target position.

[0018] A radar includes a transmitter, a receiver, and a processor. The transmitter and the receiver, both mounted on a mobile platform, are connected to the processor. The transmitter on the mobile platform transmits a time-modulated frequency diversity signal, the frequency offset of which has a coprime structure. The receiver on the mobile platform includes a coprime array, the coprime structure of which is the same as the coprime structure of the frequency offset of the frequency diversity signal. Each element of the coprime array receives a received signal reflected from the time-modulated frequency diversity signal by a target. The processor performs the following steps: transmitting the time-modulated frequency diversity signal to a target via the transmitter of the radar mounted on the mobile platform, and receiving the received signal reflected from the target via the receiver of the radar mounted on the mobile platform; determining an equivalent received signal vector of an extended virtual frequency diversity array based on the time-modulated frequency diversity signal and the received signal, the extended virtual frequency diversity array including holes and a uniform virtual frequency diversity array without holes.

[0019] A uniform virtual frequency diversity array without holes is selected. Based on the uniform received signal vector, the equivalent received signal equation is determined, the covariance matrix is ​​calculated and eigenvalue decomposition is performed, and the noise subspace is extracted to form a range-azimuth spectrum. The distance and azimuth corresponding to the spectral peaks of the range-azimuth spectrum are calculated, and the location of the target terminal is determined according to the distance and angle values.

[0020] A computer-readable storage medium storing a computer program, which, when executed by a processor, performs the following steps: transmitting a time-modulated frequency diversity signal to a target via a transmitter of a radar mounted on a mobile platform, and receiving a received signal reflected from the target via a receiver of the local radar; determining an equivalent received signal vector of an extended virtual frequency diversity array based on the frequency diversity signal and the received signal, the extended virtual frequency diversity array including holes and a uniform virtual frequency diversity array without holes; selecting a uniform virtual frequency diversity array without holes to determine a uniform received signal vector; determining an equivalent received signal steering vector based on the uniform received signal vector; and constructing a range-azimuth spectrum based on the uniform received signal vector and the equivalent steering vector, and calculating and determining the target position.

[0021] Beneficial effects: The above-mentioned target angle and distance localization method, device, radar, and storage medium extend the received signal reflected by the target to an extended virtual frequency diversity array. The number of array elements in the extended virtual frequency diversity array is greater than the number of array elements in the actual physical array. In addition, by mounting the radar on a mobile platform and simultaneously transmitting time-modulated frequency diversity signals using linear frequency-modulated continuous waves, phase compensation can be used to jointly process the received signal information at different array element positions and frequency points at multiple times, further increasing the number of virtual array elements and filling the gaps in the virtual array. This results in a final solution dimension that exceeds the dimension provided by the actual received signal, thereby effectively improving the degree of freedom for estimating the target's angle and distance. Attached Figure Description

[0022] Figure 1 This is an application environment diagram of a target angle and distance localization method in one embodiment;

[0023] Figure 2 This is a flowchart illustrating a method for locating the angle and distance of a target in one embodiment;

[0024] Figure 3 This is a schematic diagram of a coprime frequency diversity array model in one embodiment;

[0025] Figure 4 This is a schematic diagram of an extended virtual frequency diversity array in one embodiment;

[0026] Figure 5 This is a schematic diagram of the angle-distance spectrum in one embodiment;

[0027] Figure 6 Here is an SNR-distance RMSE curve for a single-target implementation;

[0028] Figure 7 This is an SNR-angle RMSE curve for a single-target embodiment;

[0029] Figure 8 A snapshot count vs. distance RMSE curve for a single-target implementation;

[0030] Figure 9 A snapshot count-angle RMSE curve for a single-target implementation;

[0031] Figure 10 Here is an SNR-distance RMSE curve for a multi-objective implementation;

[0032] Figure 11 This is an SNR-angle RMSE curve for a multi-target embodiment;

[0033] Figure 12 Here is a snapshot count vs. distance RMSE curve for a multi-target implementation.

[0034] Figure 13 Here is a snapshot count-angle RMSE curve for a multi-target implementation.

[0035] Figure 14 This is a structural block diagram of a target angle and distance positioning device in one embodiment;

[0036] Figure 15 This is a schematic diagram of the radar structure in one embodiment. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] The target angle and distance positioning method provided by this invention can be applied to, for example... Figure 1 In the application environment shown, radar 102 has a transmitter and a receiver. Radar 102 can transmit time-modulated frequency diversity signals to a far-field target 104 located around radar 102 via a transmitter mounted on a mobile platform, and can receive the received signals reflected by the target via a receiver. Radar 102 executes the target angle and distance positioning methods of various embodiments of the present invention on the far-field target 104 to locate the angle and distance of the far-field target 104.

[0039] In one embodiment, such as Figure 2 As shown, a target angle and distance localization method is provided, which can be applied to... Figure 1 The following steps, S210-S250, are used as an example to illustrate the process of using a radar in a radar system.

[0040] In step S210, a time-modulated frequency diversity signal is transmitted to the target via the transmitter of the radar mounted on the mobile platform, and the received signal reflected from the target is received by the receiver of the radar. The frequency offset of the frequency diversity signal has the same coprime structure as the coprime array of the receiver.

[0041] Step S220: Perform phase compensation based on the time-modulated frequency diversity signal and the received signals at different times.

[0042] In one embodiment, step S220 includes the following steps S221-S224.

[0043] Step S221: Based on the coprime structure information of the receiver's coprime array, establish a coprime array model, which consists of two uniform sparse subarrays.

[0044] For example, in this step, a corresponding coprime array model can be established based on the coprime structure information of the receiver's coprime array. This coprime array model consists of two uniform sparse subarrays. One subarray (called the first subarray) has a total of M elements and an element spacing of Nd. The other subarray (called the second subarray) has a total of N elements and an element spacing of Md, where d is the unit distance. The first element of both subarrays can share the same element, thus the total number of physical elements in this coprime array is M+N-1. The expression for the coprime set of elements corresponding to the two subarrays is as follows:

[0045]

[0046]

[0047]

[0048] The position of the array element can be represented as:

[0049]

[0050] For example, in this step, similarly, based on the frequency diversity information of the transmitter's transmitted frequency diversity signal, a corresponding frequency diversity model is established, with the different frequencies of the transmitted signal set as follows:

[0051]

[0052] Where d = λ / 2 represents the unit element spacing, and λ represents the wavelength. The reference carrier frequency is f0, and Δf represents the minimum unit offset of the carrier frequency. It can be seen that the frequency offset of the established frequency diversity model has the same coprime structure characteristics as the coprime array model; that is, the offset array corresponding to the frequency offset of the frequency diversity model is the same as the offset array of the coprime array model.

[0053] Step S222: Determine the received signal vector of the coprime array based on the received signal, the time modulation frequency diversity model, and the coprime array model mounted on the mobile platform.

[0054] For example, in this step, based on the received signal, frequency diversity model, and coprime array model, it is assumed that there are Q uncorrelated far-field targets, and the q-th (q=1,2,…Q) target is located in a two-dimensional polar coordinate system (θ). q ,R q ), where θ q and R q Let represent the angle and distance of the q-th target, respectively. The transmitting antenna transmits LFMCW signals with frequency diversity at a scanning slope μ, and the moving platform has a speed of v. The received signal corresponding to time t can be expressed as:

[0055]

[0056] Where φ q (t) represents the complex scattering coefficient, c is the speed of light, and n(t) represents additive white Gaussian noise.

[0057]

[0058] Where, d l and Δf l Let represent the position and frequency of the l-th array element, respectively. The signal vector is represented as...

[0059] s(t)=[s1(t),s2(t),…s Q (t)] T (6)

[0060] in,

[0061]

[0062] Step 223: Determine the received signal vector of the coprime array based on the received signals at different times, the time modulation frequency diversity model, and the coprime array model mounted on the mobile platform.

[0063] For example, the element positions and carrier frequencies of a frequency diversity coprime array model for LFMCW on a mobile platform can be represented as follows: and Since the position and frequency offset of the array change continuously with time, at time t+τ, the output of the receiving array is expressed as:

[0064]

[0065] in

[0066]

[0067] Choosing vτ = d = λ / 2 and μτ = Δf, the frequency and position of the frequency diversity coprime array of a mobile platform-based LFMCW can be expressed as follows: and in

[0068]

[0069] The received signal vector at time t+τ can be expressed as

[0070]

[0071] Taking M=3 and N=5 as an example, the coprime frequency diversity array model determined through steps S221, S222 and S223 is as follows: Figure 3 As shown, the coprime frequency diversity array model contains information about the coprime array model and the time-modulated frequency diversity model mounted on the mobile platform.

[0072] Step 224, phase compensation;

[0073] For example, in order to process the received signals at time t and time t+τ simultaneously, a phase correction factor needs to be compensated to generate a phase-synchronized received signal vector. The compensated signal can be expressed as follows:

[0074]

[0075] in, Noise after phase compensation

[0076]

[0077] Combining formula (4) and formula (12), we get

[0078]

[0079] in

[0080]

[0081] Step S230 determines the equivalent received signal vector of the extended virtual frequency diversity array based on the time-modulated frequency diversity signal and the received signal. The extended virtual frequency diversity array includes perforated and non-perforated uniform virtual frequency diversity arrays. Taking M=3 and N=5 as an example, the extended virtual frequency diversity array determined by step S230 is as follows: Figure 4 As shown, this extended virtual frequency diversity array model contains information from a coprime array model and a time-modulated frequency diversity model on a mobile platform.

[0082] Step S240: Select a uniform virtual frequency diversity array without holes to determine the uniform received signal vector, and determine the equivalent received signal steering vector based on the uniform received signal vector;

[0083] For example, in this step, based on the received signal vector determined in the preceding steps, the covariance matrix of the coprime frequency diversity array can be written as:

[0084]

[0085] Among them, R ss =diag{p1,…,p Q}, p q This represents the scattering power of the q-th target. This represents the power of the Gaussian noise. Since the scattering frequency is much smaller than the carrier frequency, the scattering coefficient of each target can be approximated as independent of the carrier frequency. In practical applications, we use T0. s A snapshot is used instead of the estimated covariance matrix, i.e.:

[0086]

[0087] The covariance matrix is ​​vectorized to obtain the equivalent received signal vector of the extended virtual frequency diversity array, which includes the steering vector of the extended virtual frequency diversity array; the extended virtual frequency diversity array (i.e., non-uniform virtual frequency diversity array) includes holes and uniform virtual frequency diversity arrays without holes.

[0088] For example, in this step, the equivalent received signal vector of the extended virtual frequency diversity array can be obtained by vectorizing the covariance matrix Rx:

[0089]

[0090] Where p = [p1, p2, ... p Q ] T Indicates the target scattering power.

[0091]

[0092] A v Each element in the array is equivalent to a virtual array element, whose position and frequency are respectively related to... and The difference set is related, where

[0093] Step S250: Based on the uniform received signal vector and the equivalent steering vector, construct the range-azimuth spectrum and calculate to determine the target position.

[0094] For example, the virtual signal y v This is equivalent to a single-shot signal degraded due to coherence, therefore spatial smoothing is required to recover y. v The rank of the covariance matrix. Then, the 2D MUSIC algorithm can be directly applied to the smoothed signal to jointly estimate the distance and angle of all targets, i.e., expressed as...

[0095]

[0096] Among them, U N Let a represent the noise subspace of the spatial smooth covariance matrix, and let vector a be a. p,f (r,θ) represents the steering vector of the virtual signal, where U is the maximum index of the continuous portion of the virtual array, and a p,f(r,θ) can be specifically written as

[0097]

[0098] In the target angle and distance localization methods of the above embodiments of the present invention, coprime sampling technology is introduced, and the concept of a coprime frequency diversity array (i.e., a coprime frequency control array) is proposed. This coprime frequency control array uses the concept of differential co-array to circumvent the limitations of physical sampling. Nevertheless, under the equivalence of coprime frequency control array co-array and frequency difference, the resulting virtual frequency control array contains holes. In order to make full use of the array aperture and the degrees of freedom of the virtual frequency control array, the present invention further expands the hole position, mounts the radar on a mobile platform, and transmits time-modulated frequency diversity signals, combining the received signals sampled at different times, thereby expanding the degrees of freedom.

[0099] It should be understood that, although Figure 2 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 2 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed 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 some of the sub-steps or stages of other steps.

[0100] Simulation Experiment

[0101] The invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that these specific embodiments are not intended to limit the invention, but are only used to verify its effectiveness.

[0102] This invention proposes a joint estimation method for the angular distance of time-modulated frequency diversity coprime arrays on mobile platforms. To verify the performance advantages of the algorithm, an example flow of this invention is given below.

[0103] (1) Simulation experiment parameter settings

[0104] Consider a coprime array of 7 elements, where M = 3 and N = 5. The original frequency diversity coprime array, here named the FDCA I scheme, has 7 physical elements, distributed at positions s. I On d, the frequency offset is s I Δf, where The reference frequency f0 = 7 GHz, and the unit frequency offset Δf = 30 kHz. Another frequency diversity array that can be used for comparison, with both array position and frequency offset remaining constant, is named the FDCA II array. It can generate continuous virtual arrays of the same size. The element positions of this scheme are distributed in s... III On d, the frequency offset is s III Δf, where The element position corresponding to the frequency diversity coprime array with linear time-modulated frequency modulation proposed in this invention on the mobile platform is s. II d, frequency offset is s II Δf, where

[0105] (2) Degrees of freedom analysis

[0106] The array scheme proposed in this invention has 7 array elements, 7 frequency offsets, and 121 achievable degrees of freedom; while the original FDCA I scheme has the same number of array elements and frequency offsets, but only 48 achievable degrees of freedom. We first consider the case with 110 signal sources. Since the number of targets exceeds the original FDCA's achievable degrees of freedom of 48, traditional FDCA cannot detect all targets. We fix the signal-to-noise ratio and the number of snapshots at 20dB and 1000, respectively. We assume that the 110 unrelated targets are evenly distributed across 11 distance values ​​between [-70°, 65°] and 10 angle values ​​between [200m, 4200m]. Figure 5 As shown, the proposed solution can accurately estimate all peak values ​​of 110 targets in a two-dimensional spatial spectrum, which proves the effectiveness of the proposed solution in improving the degrees of freedom.

[0107] (3) Performance comparison of single-objective estimation

[0108] Consider a far-field target located at (30°, 1500m). We initially fix the number of snapshots at 500, varying the signal-to-noise ratio between -10dB and 20dB. The root mean square error curves for angle and distance estimation are shown below. Figure 6 and Figure 7 As shown in the figure, it is easy to observe that the method proposed in this invention outperforms the original FDCA I and FDCA II schemes in terms of estimation accuracy for both angle and distance. If we change the number of snapshots and keep the signal-to-noise ratio fixed at 10dB, Figure 8 and Figure 9 The comparison of estimation errors for the three schemes is shown. Similarly, the scheme proposed in this invention outperforms the traditional FDCA method in terms of root mean square error. Thus, the effectiveness of the method proposed in this invention in terms of degrees of freedom and estimation accuracy has been verified.

[0109] (4) Performance comparison of multi-objective estimation

[0110] Further consider the case with 36 unrelated targets. Assume these 36 targets are uniformly distributed across six angle values ​​between [-60°, 60°] and six distance values ​​between [200m, 4200m]. Similarly, Figure 10 and 11 The performance of angle and distance estimation versus signal-to-noise ratio (SNR) variation estimation was compared, with a fixed number of snapshots (500). As the SNR increased, the root mean square (RMS) error of all methods gradually decreased, while the proposed method achieved the lowest RMS error. Next, we compared performance based on the number of snapshots, with the SNR set to 10 dB. Figure 12 and 13 Numerical results further confirm that the estimation errors produced by the two traditional FDCA methods are higher than those of the proposed scheme. The simulation results clearly demonstrate the advantages of the proposed shift-time modulation frequency diversity coprime array scheme in improving the accuracy of degrees of freedom and angular distance estimation.

[0111] The above description is merely 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 within the scope of protection of the present invention.

[0112] In one embodiment, such as Figure 7 As shown, a target angle and distance positioning device 700 is provided, including: a signal transceiver module 701, a phase compensation module 702, a virtual frequency diversity extension module 703, an equivalent received signal construction module 704, and a target positioning module 705, wherein:

[0113] The signal transceiver module 701 is used to transmit time-modulated frequency diversity signals to the target through the transmitter of the local radar mounted on the mobile platform, and to receive the received signals reflected by the target through the receiver of the local radar.

[0114] Phase compensation module 702 performs phase compensation based on the time-modulated frequency diversity signal and the received signals at different times.

[0115] The virtual frequency diversity extension module 703 is used to determine the equivalent received signal vector of the extended virtual frequency diversity array based on the frequency diversity signal and the received signal. The extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes.

[0116] The equivalent received signal construction module 704 selects a uniform virtual frequency diversity array without holes to determine a uniform received signal vector, and determines an equivalent received signal steering vector based on the uniform received signal vector.

[0117] The target positioning module 705 constructs a range-azimuth spectrum based on the uniformly received signal vector and the equivalent steering vector, and calculates and determines the target position.

[0118] Specific limitations regarding the target angle and distance positioning device 700 can be found in the limitations of the target angle and distance positioning method described above, and will not be repeated here. Each module of the aforementioned target angle and distance positioning device 700 can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in a computer device, or stored in software in the memory of a computer device, so that the processor can call and execute the corresponding operations of each module.

[0119] In one embodiment, such as Figure 8 As shown, a radar 800 mounted on a mobile platform is provided, including a transmitter 810, a receiver 820 and a processor 830. The transmitter 810 and the receiver 820 are respectively connected to the processor 830. The transmitter 810 is used to transmit a time-modulated frequency diversity signal, and the frequency offset of the frequency diversity signal has a coprime structure.

[0120] The receiver 820 includes a coprime array 821. The coprime structure of the coprime array 821 is the same as the coprime structure of the frequency offset of the frequency diversity signal transmitted by the transmitter 810. Each element of the coprime array 821 is used to receive the received signal formed by the reflection of the frequency diversity signal from the far-field target 200.

[0121] Specifically, in one embodiment, the coprime array 821 of the receiver 820 includes a first subarray formed by a plurality of array elements (antennas) uniformly arranged at a first array element interval and a second subarray formed by a plurality of array elements uniformly arranged at a second array element interval. The first array element interval and the second array element interval are not equal. The first array element of the first subarray and the first array element of the second subarray can share the same array element, and the plurality of array elements of the first subarray and the plurality of array elements of the second subarray are arranged together to form the coprime array 821, so that the coprime array 821 has a coprime structure.

[0122] In one embodiment, transmitter 810 may include a single antenna or multiple antennas. The frequency offset of the time-modulated frequency diversity signal transmitted by transmitter 810 through its single antenna or by multiple antennas includes a first frequency diversity formed by multiple transmission frequencies uniformly offset by a first unit frequency offset and a second frequency diversity formed by multiple transmission frequencies uniformly offset by a second unit frequency offset. The first unit frequency offset and the second unit frequency offset are not equal. The first transmission frequencies of the first frequency diversity and the second frequency diversity may have the same frequency. The multiple transmission frequencies of the first frequency diversity and the multiple transmission frequencies of the second frequency diversity are arranged together to form the frequency offset of the frequency diversity signal. Thus, the frequency offset of the frequency diversity signal also has a coprime structure, and the coprime structure of the frequency offset of the frequency diversity signal can be the same as the coprime structure of the coprime array 821.

[0123] Processor 830 is used to perform the following steps:

[0124] The transmitter 810 of the radar 800 mounted on the mobile platform transmits a time-modulated frequency diversity signal to the far-field target 200, and the receiver 820 of the radar 800 receives the received signal reflected by the far-field target 200.

[0125] Phase compensation is performed based on the time-modulated frequency diversity signal and the received signals at different times;

[0126] Based on the received signals at different times after phase compensation, the equivalent received signal vector of the extended virtual frequency diversity array is determined. The extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes.

[0127] A uniform virtual frequency diversity array without holes is selected to determine the uniform received signal vector, and based on the uniform received signal vector, the equivalent received signal steering vector is determined.

[0128] Based on the uniform received signal vector and the equivalent steering vector, a range-azimuth spectrum is constructed, and the target position is determined by solving the range-azimuth spectrum. The angle and distance of the target are located by 200 degrees.

[0129] In other embodiments, the processor 830 also performs the steps of the target angle and distance positioning method as described in any of the embodiments above.

[0130] Those skilled in the art will understand that Figure 8 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the radar to which the present invention is applied. A specific radar may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0131] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0132] The radar transmitter mounted on the mobile platform transmits a time-modulated frequency diversity signal to the target, and the receiver of the radar on the local end receives the received signal reflected by the target.

[0133] Phase compensation is performed based on the time-modulated frequency diversity signal and the received signals at different times;

[0134] Based on the received signals at different times after phase compensation, the equivalent received signal vector of the extended virtual frequency diversity array is determined. The extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes.

[0135] A uniform virtual frequency diversity array without holes is selected to determine the uniform received signal vector, and based on the uniform received signal vector, the equivalent received signal steering vector is determined.

[0136] Based on the uniform received signal vector and the equivalent steering vector, a range-azimuth spectrum is constructed, and the target position is determined by calculation.

[0137] In other embodiments, when the computer program is executed by a processor, it also implements the steps of the target angle and distance positioning method as described in any of the embodiments above.

[0138] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided by this 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. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0139] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0140] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A target localization method using a time-modulated coprime frequency control array mounted on a mobile platform, characterized in that, Specifically, the steps include the following: Step 1: Transmit a time-modulated frequency diversity signal to the target through the radar transmitter mounted on the mobile platform, and receive the received signal reflected by the target through the receiver of the radar on the local end; Step 2: Perform phase compensation based on the time-modulated frequency diversity signal and the received signals at different times; Step 3: Based on the received signals at different times after phase compensation, determine the equivalent received signal vector of the extended virtual frequency diversity array, wherein the extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes. Step 4: Select a uniform virtual frequency diversity array without holes to determine the uniform received signal vector, and determine the equivalent received signal steering vector based on the uniform received signal vector; Step 5: Based on the uniformly received signal vector and the equivalent steering vector, construct the range-azimuth spectrum and calculate to determine the target position; The frequency offset of the frequency diversity signal has the same coprime structure as the coprime array of the receiver; The mobile platform moves at a constant linear speed, and the direction of motion is consistent with the direction of the extended virtual frequency diversity array. The speed of the mobile platform is constant and known. The time-modulated frequency diversity signal is a linear frequency-modulated continuous wave, and the signal modulation frequency is constant and known. The target should be a far-field target, and the target is considered stationary at different sampling times, with the relative positions of the target and the moving platform fixed; Step 2 includes: Based on the time delay between the current time and the initial time and the modulation frequency of the time modulation frequency, compensate for the phase difference caused by the difference between the frequency of the time modulation frequency diversity signal at the current time and the frequency of the time modulation frequency diversity signal at the initial sampling time; Step 3 includes: Step 3.1: Based on the coprime structure information of the receiver's coprime array, establish a coprime array model, which consists of two uniform sparse subarrays; Step 3.2: Establish a frequency diversity model based on the frequency diversity information of the frequency diversity signal transmitted by the transmitter; Step 3.3: Determine the received signal vector of the coprime array based on the received signal, the frequency diversity model, and the coprime array model; Step 3.4: Determine the covariance matrix of the coprime array based on the received signal vector; Step 3.5: Vectorize the covariance matrix to obtain the equivalent received signal vector of the extended virtual frequency diversity array, the equivalent received signal vector including the steering vector of the extended virtual frequency diversity array; the extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes.

2. The target positioning method for a time-modulated coprime frequency control array mounted on a mobile platform according to claim 1, characterized in that, Step 4 includes: Step 4.1: Select a hole-free uniform virtual frequency diversity array in the extended virtual frequency diversity array, and determine the non-negative received signal vector in the non-negative region; Step 4.2: Determine the non-negative covariance matrix of the coprime array of the receiver based on the non-negative received signal vector; Step 4.3: Vectorize the non-negative covariance matrix to obtain the non-negative equivalent virtual array received signal vector; Step 4.4: Based on the guide vector of the coprime array without holes and the guide vector of the frequency offset without holes, determine the guide vector of the uniform virtual frequency diversity array without holes.

3. The target positioning method for a time-modulated coprime frequency control array mounted on a mobile platform according to claim 1, characterized in that, Step 5 includes: Step 5.1: Calculate the estimated value of the covariance matrix corresponding to the uniformly received signal based on the uniformly received signal vector; Step 5.2: Perform eigenvalue decomposition on the estimated value of the covariance matrix to extract the noise subspace; Step 5.3: Calculate the range-azimuth spectrum based on the noise subspace and the equivalent steering vector of the equivalent received signal; Step 5.4: Identify the range-azimuth spectrum, determine the highest spectral peak of the range-azimuth spectrum, and calculate the distance and azimuth corresponding to the highest spectral peak; Step 5.5: Determine the position of the target based on the azimuth angle value.

4. A target angle and distance positioning device, used to implement the method according to any one of claims 1-3, characterized in that, The device includes: The signal transceiver module is used to transmit time-modulated frequency diversity signals to the target through the transmitter of the radar mounted on the mobile platform, and to receive the received signals reflected by the target through the receiver of the radar on the local end. The phase compensation module performs phase compensation based on the time-modulated frequency diversity signal and the received signals at different times; A virtual frequency diversity extension module is used to determine the equivalent received signal vector of the extended virtual frequency diversity array based on the frequency diversity signal and the received signal. The extended virtual frequency diversity array includes holes and a uniform virtual frequency diversity array without holes. The equivalent received signal construction module selects a uniform virtual frequency diversity array without holes to determine a uniform received signal vector, and determines an equivalent received signal steering vector based on the uniform received signal vector. The target positioning module constructs a range-azimuth spectrum based on the uniformly received signal vector and the equivalent steering vector, and calculates and determines the target position.

5. A radar comprising a transmitter, a receiver, and a processor, wherein the transmitter and the receiver are respectively connected to the processor, characterized in that: The transmitter is used to transmit a time-modulated frequency diversity signal, the frequency offset of which has a coprime structure. The receiver includes a coprime array mounted on a mobile platform. The coprime structure of the coprime array is the same as the coprime structure of the frequency diversity signal with frequency offset. Each element of the coprime array is used to receive the received signal formed by the target reflecting the time-modulated frequency diversity signal. The processor is used to perform the steps of the method as described in any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 3.

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