Radar, radar parameter estimation method, electronic equipment and storage medium

Abstract

The invention provides a radar, a radar parameter estimation method, electronic equipment and a storage medium, the radar comprises a transmitting array, a receiving array and a processing unit, and the processing unit is connected with the receiving array; the number of transmitting array elements in the transmitting array is 2N, the distance between the transmitting array elements is Md, the number of receiving array elements in the receiving array is M, the distance between the receiving array elements is Nd, N and M are co-prime integers, and d is the distance between unit array elements; the transmitting array comprises at least one sub-array, each sub-array comprises at least one transmitting array element, and the frequency offset of each sub-array is configured to be a product of unit frequency offset and a frequency offset coefficient; the processing unit is used for carrying out frequency compensation on a frequency mixing signal corresponding to each receiving array element, the frequency mixing signal is obtained by carrying out frequency mixing processing on receiving signals received by the receiving array elements, the frequency compensation value of the mth receiving array element is mP times of the unit frequency offset, and the frequency offset coefficient and P are co-prime integers.

Description

Technical Field

[0001] The present application relates to the field of radar analysis technology, and in particular to a radar, a radar parameter estimation method, an electronic device and a storage medium. Background Art

[0002] The mutually prime frequency diversity array and multiple-input multiple-output (FDA-MIMO) radar is a radar system that combines the frequency diversity array (FDA) and multiple-input multiple-output (MIMO) technologies. The frequency diversity array realizes the beam related to the angular distance by introducing a small frequency increment between adjacent transmitting elements. The MIMO technology increases the system's degree of freedom through multiple transmitting and receiving elements, and improves the maximum number of resolvable targets and the resolution of the distance and angle dimensions. The transmitting array and receiving array of the mutually prime FDA-MIMO radar are a set of mutually prime uniform linear arrays.

[0003] Traditional coprime FDA-MIMO radars improve the radar's degrees of freedom by vectorizing the sampling covariance matrix and constructing virtual space-frequency array elements. However, this processing method results in the data used for target parameter estimation being a single-snapshot signal. Most current target parameter estimation algorithms are based on subspace-based multi-snapshot algorithms, which means that coprime FDA-MIMO radars cannot use subspace-based algorithms, limiting their practical applications. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a radar, a radar parameter estimation method, an electronic device and a storage medium to solve the problem of limited application of subspace algorithms on mutually prime FDA-MIMO radars and enhance the universality of mutually prime FDA-MIMO radars.

[0005] In a first aspect, the present application provides a radar, comprising: a transmitting array, a receiving array and a processing unit, wherein the processing unit is connected to the receiving array; the number of transmitting array elements in the transmitting array is 2N, and the spacing between the transmitting array elements is Md, the number of receiving array elements in the receiving array is M, and the spacing between the receiving array elements is Nd, wherein N and M are mutually prime integers, and d is the unit array element spacing; the transmitting array comprises at least one subarray, each subarray comprises at least one transmitting array element, and the frequency offset of each subarray is configured as the product of a unit frequency offset and a frequency offset coefficient; the processing unit is used to perform frequency compensation on a mixing signal corresponding to each receiving array element, wherein the mixing signal is obtained by mixing a received signal received by the receiving array element, the frequency compensation value of the mth receiving array element is mP times the unit frequency offset, and the frequency offset coefficient and P are mutually prime integers.

[0006] In the above scheme, by introducing frequency compensation at the receiving array end, a virtual frequency offset can be generated after matched filtering, thereby improving the freedom of the radar in the frequency dimension. A higher frequency degree of freedom enables the radar to perform more complex signal processing. When performing subsequent target parameter estimation, the radar can perform multiple sampling to obtain multi-snapshot signals, thereby ensuring the applicability of the subspace algorithm. Compared with the traditional coprime FDA-MIMO radar, the radar will not have the problem of single-snapshot parameter estimation when estimating target parameters, thereby improving the universality of the practical application of the radar array.

[0007] As an optional manner, the transmitting array includes a first subarray and a second subarray, the frequency offset coefficient of the first subarray is Q1, the frequency offset coefficient of the second subarray is Q2, and Q1, Q2 and P are coprime integers.

[0008] In the above scheme, the radar's transmitting array is divided into two sub-arrays, namely the first sub-array and the second sub-array, and different frequency offsets are set for each sub-array. Furthermore, the distance and angle coupling phenomenon can be eliminated, and the distance and angle ambiguity problems that occur during target parameter estimation can be effectively solved, so that more detection targets can be correctly distinguished and the target resolution capability can be improved.

[0009] As an optional manner, the transmitting array includes a third sub-array, the frequency deviation coefficient of the third sub-array is Q3, and Q3 and P are coprime integers.

[0010] In the above scheme, the radar's transmitting array includes only one subarray. By introducing frequency compensation at the receiving array end, a virtual frequency deviation can be generated after matched filtering, thereby improving the radar's degree of freedom in the frequency dimension. When performing subsequent target parameter estimation, the radar can perform multiple sampling to obtain multi-snapshot signals, thereby ensuring the applicability of the subspace algorithm. Compared with the traditional coprime FDA-MIMO radar, the radar will not have the problem of single-snapshot parameter estimation when estimating target parameters, thereby improving the universality of the practical application of the radar array.

[0011] As an optional method, the transmission signal of the nth transmitting array element is expressed by the following formula: Among them, s n (t) is the transmit signal, n is the index of the transmit array element, n=0, 1, ..., 2N-1, E is the total power of the transmit signal of the transmit array, ψ n (t) is the baseband modulation signal corresponding to the transmit signal of the nth transmit array element, j is an imaginary unit, f0 is the carrier frequency of the transmit signal of the transmit array, Δf is the unit frequency deviation, and T is the pulse duration of the transmit signal of the transmit array.

[0012] In the above scheme, the frequency offset between different transmitting array elements is Q3Δf, and the radar system realizes frequency diversity, thereby increasing the system's degree of freedom in the frequency dimension. The baseband modulation signal is designed to meet the orthogonal condition, and the signals of different transmitting array elements are orthogonal in time, which helps to separate and process the signals of each transmitting array element at the receiving array end, thereby improving the efficiency and accuracy of signal processing.

[0013] As an optional method, the received signal of the mth receiving element is expressed by the following formula: Among them, y m (t) is the received signal, m is the index of the receiving array element, m=0,…,M-1, ξ is the complex reflection coefficient of the detected target, τ n,m It is the time required for the echo signal emitted by the nth transmitting element to be captured by the mth receiving element.

[0014] In the above scheme, the receiving signal model takes into account the interaction between different transmitting array elements n and different receiving array elements m to achieve joint estimation of angle and distance. Since the received signal contains the frequency offset Q3Δf between different transmitting array elements, the radar can improve the resolution of angle and distance through frequency diversity, thereby enhancing the target recognition and resolution capabilities.

[0015] As an optional method, the following formula is used to express the target signal obtained after the frequency compensation of the received signal corresponding to the mth receiving array element: in, is the target signal, r0 is the distance parameter of the detection target, θ0 is the angle parameter of the detection target, and c is the speed of light.

[0016] In the above scheme, through frequency compensation, the interference caused by Doppler expansion can be reduced, making the received signal more concentrated in the Doppler dimension. In addition, different channel signals can achieve coherent accumulation and enhance the coherence of the signal, thereby improving the radar's detection capability for targets and improving the radar's spatial resolution and target positioning accuracy.

[0017] As an optional manner, the processing unit is further used to estimate the angle and distance parameters of the detection target according to the received signal corresponding to the transmitted signal of each transmitting array element received by each receiving array element through a subspace algorithm.

[0018] In a second aspect, the present application provides a radar parameter estimation method, which is applied to a processing unit in the radar described in the first aspect. The radar parameter estimation method includes: performing frequency compensation on a mixing signal corresponding to each receiving array element, wherein the mixing signal is obtained by mixing a received signal received by the receiving array element, and the frequency compensation value of the mth receiving array element is mP times the unit frequency deviation, and the frequency deviation coefficient and P are coprime integers; estimating the angle and distance parameters of the detected target according to a subspace algorithm based on the received signal corresponding to the transmitted signal of each transmitting array element received by each receiving array element.

[0019] In traditional mutually prime FDA-MIMO radars, due to the limitations of frequency offset and array structure, only a single snapshot can be used for target parameter estimation, which limits the radar performance. In the above scheme, by introducing frequency compensation that is mutually prime with the frequency offset of the transmitting array at the receiving array end, the radar can use the multi-snapshot algorithm to estimate the target parameters and improve the performance of target parameter estimation.

[0020] In a third aspect, the present application provides an electronic device comprising: a processor, a memory and a bus, wherein the processor and the memory communicate with each other via the bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the method steps of the first aspect.

[0021] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method steps of the first aspect are executed.

[0022] In a fifth aspect, the present application provides a computer program product, comprising: a computer program, wherein the computer program executes the method steps of the first aspect when executed by a processor.

[0023] Other features and advantages of the present application will be described in the subsequent description, and in part will become apparent from the description, or will be understood by implementing the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of an array model of a mutually prime FDA-MIMO radar;

[0026] Figure 2 A schematic diagram of a radar array model provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of a processing flow of a processing unit of a radar provided in an embodiment of the present application;

[0028] Figure 4 A schematic diagram of the space-frequency position distribution of a virtual array of a radar provided in an embodiment of the present application;

[0029] Figure 5 A schematic diagram of a target estimation spectrum of an SDCFDA-MIMO radar provided in an embodiment of the present application;

[0030] FIG6 is a schematic diagram of a first result of a resolution performance comparison simulation experiment provided in an embodiment of the present application;

[0031] FIG7 is a schematic diagram of a second result of a resolution performance comparison simulation experiment provided in an embodiment of the present application;

[0032] FIG8 is a schematic diagram of a third result of a resolution performance comparison simulation experiment provided in an embodiment of the present application;

[0033] FIG9 is a schematic diagram of the results of a simulation experiment comparing the degrees of freedom of an array provided in an embodiment of the present application;

[0034] FIG10 is a schematic diagram showing a two-dimensional estimated spectrum of a ULA-UFO array without applying frequency compensation;

[0035] Fig.11 A schematic diagram showing a two-dimensional estimated spectrum after frequency compensation is applied to the ULA-UFO array;

[0036] FIG12 is a schematic diagram showing the results of a simulation experiment comparing the distance and angle estimation performance provided in an embodiment of the present application;

[0037] Fig.13 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0039] It should be noted that all technical and scientific terms used in this document have the same meanings as those generally understood by technicians in the technical field to which this application belongs; the terms used in this document are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0040] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0041] To facilitate understanding, the professional technologies involved in the technical solutions provided in the embodiments of the present application are introduced.

[0042] For FDA-MIMO radar, the angular resolution of the target is limited by the radar aperture, the range resolution of the target is related to the frequency offset, and the maximum number of resolvable targets of the radar is determined by the array freedom and the frequency offset freedom. For a traditional uniform frequency offset FDA radar with N array elements, the range and angle dimensions can only be obtained. degrees of freedom and With a resolution of , traditional parameter estimation algorithms can only distinguish N-1 targets at most.

[0043] In order to improve the resolution of distance and angle dimensions and the maximum number of resolvable targets without increasing the cost of radar hardware, a mutually prime FDA-MIMO radar has been proposed in recent years. Figure 1 , Figure 1Schematic diagram of an array model of a mutually prime FDA-MIMO radar. The transmitting array and receiving array of the mutually prime FDA-MIMO radar are set as a group of mutually prime uniform linear arrays. The number of array elements in the transmitting array and the receiving array are 2N1 and M1 respectively. The array element spacings are M1d and N1d respectively, where d represents the unit array element spacing. N1 and M1 are mutually prime integers. A mutually prime frequency offset is set at the transmitting end. The transmitting frequency of the nth transmitting array element is f n =f0+p n Δf,n=0,1,…2N1-1, that is, the transmission frequency of the nth transmitting array element is equal to f0 and the frequency deviation f n =p n The sum of Δf, f0 is the carrier frequency of the transmitted signal, Δf is the unit frequency deviation, p n The integer coefficient representing the frequency offset of the nth transmitting array element, p n is a set of mutually prime integers.

[0044] Similar to the method of improving the system degrees of freedom of coprime MIMO radar, coprime FDA-MIMO radar also improves the radar degrees of freedom by vectorizing the sampling covariance matrix and constructing virtual space-frequency array elements, but ultimately the data used for target parameter estimation is a single snapshot signal.

[0045] Most of the current target parameter estimation algorithms are based on subspace-based multi-snapshot algorithms, which makes it impossible for coprime FDA-MIMO radars to directly apply traditional parameter estimation algorithms for target parameter estimation. The traditional coprime MIMO radar overcomes this limitation by spatially smoothing the single snapshot signal to make it suitable for subspace-based algorithms, but this method can only use continuous virtual array elements. In coprime FDA-MIMO radars, in addition to array element position information, single snapshot signals also contain virtual frequency offset information. There are obvious differences in the continuity of virtual frequency offset information, which limits the application of spatial smoothing technology in coprime FDA-MIMO radars. As a result, coprime FDA-MIMO radars cannot use subspace-based algorithms and can only design single snapshot algorithms for target parameter estimation, which is not conducive to practical applications.

[0046] Reference Figure 2 , Figure 2 A schematic diagram of an array model of a radar provided in an embodiment of the present application includes: a transmitting array and a receiving array; the number of transmitting array elements in the transmitting array is 2N, and the spacing between the transmitting array elements is Md, the number of receiving array elements in the receiving array is M, and the spacing between the receiving array elements is Nd, wherein N and M are coprime integers, and d is the unit array element spacing; the transmitting array includes at least one subarray, each subarray includes at least one transmitting array element, and the frequency offset of each subarray is configured as the product of the unit frequency offset and the frequency offset coefficient.

[0047] The radar also includes a processing unit connected to the receiving array, and the processing unit is used to perform frequency compensation on the mixing signal corresponding to each receiving array element, wherein the mixing signal is obtained by mixing the receiving signal received by the receiving array element, and the frequency compensation value of the mth receiving array element is mP times the unit frequency deviation, and the frequency deviation coefficient and P are coprime integers.

[0048] The unit element spacing can be set to λ is the signal wavelength. The radar's transmitting array element position set is:

[0049] P ac,t ={nM|n=0,1,…,2N-1}d;

[0050] The receiving array element position set of DCFDA-MIMO radar is:

[0051] P ac,r ={mN|m=0,1,…,M-1}d;

[0052] The transmission frequency f of the nth transmitting array element n It is expressed as:

[0053] f n =f0+nQΔf,n=0,1,…,2N-1; where f0 is the carrier frequency, Q is the frequency deviation coefficient, Δf is the unit frequency deviation, and QΔf is the frequency offset of the transmitting array.

[0054] Different from the traditional mutual prime FDA-MIMO radar, the mth receiving array element of the radar adds frequency compensation Δf during signal processing. m , Δf m The expression is:

[0055] Δf m =mPΔf, m=0,1,…,M-1; the frequency deviation coefficients Q and P are coprime integers.

[0056] Since the radar introduces frequency compensation at the receiving end, the receiving end signal processing chain in the processing unit needs to be redesigned. Figure 3 , Figure 3 The processing flow diagram of a processing unit of a radar provided in an embodiment of the present application is as follows. First, the processing unit compares the received signal of the mth receiving element with the received signal of the e -j2πf0t The mixed signal is obtained by mixing. Then, the received signal of the mth receiving array element is frequency compensated according to the frequency compensation value. The compensated signal is converted into digital-to-analog by the digital-to-analog converter. Finally, the compensated received signal of the mth receiving array element is transmitted to the 2N channels and respectively mixed with φ n,m (t) performs matched filtering, φ n,mThe expression of (t) is:

[0057] φ n,m (t) = ψ n (t)e -j2π(nQΔf+mPΔf)t ;

[0058] Through the above processing flow, a target echo signal for target parameter estimation can be obtained, including a transmission signal of the nth transmitting array element received by the mth receiving array element.

[0059] The following is an example of a radar with N=2, M=3, f0=0, Q=3, Δf=1, and P=5. P and Q satisfy that they are mutually prime integers. Then, the transmitting frequencies of the transmitting array are [0, 3, 6, 9] (unit: kHz), and the frequency compensation values ​​of the receiving array are [0, 5, 10] (unit: kHz). Figure 4 , Figure 4 A schematic diagram of the space-frequency position distribution of a virtual array of a radar provided in an embodiment of the present application shows that the degrees of freedom of the space dimension and the frequency dimension of the virtual array are both 12. When performing subsequent target parameter estimation, the radar can perform multiple sampling to obtain multi-snapshot signals, thereby overcoming the problem that the data used for target parameter estimation in traditional coprime FDA-MIMO radars is a single snapshot signal.

[0060] In the above scheme, by introducing frequency compensation at the receiving array end, a virtual frequency deviation can be generated after matched filtering, thereby improving the radar's degree of freedom in the frequency dimension. A higher frequency degree of freedom enables the radar to perform more complex signal processing. When performing subsequent target parameter estimation, the radar can perform multiple sampling to obtain multi-snapshot signals, thereby ensuring the applicability of the subspace algorithm. Compared with the traditional coprime FDA-MIMO radar, the radar will not encounter the problem of single-snapshot parameter estimation when estimating target parameters, thereby improving the universality of the practical application of the radar array.

[0061] In some embodiments, the transmit array includes a first sub-array and a second sub-array, the frequency offset coefficient of the first sub-array is Q1, the frequency offset coefficient of the second sub-array is Q2, and Q1, Q2 and P are coprime integers.

[0062] When the transmitting array includes two sub-arrays, it is assumed that the true position of the detected target is (r,θ) and the fuzzy position is The true position and the fuzzy position have the same phase information and can be expressed as:

[0063]

[0064] When n=1, m=1 and When , the above formula can be simplified to:

[0065]

[0066] Among them, k n and k m is a positive integer,

[0067] Solving the above formula, we can get:

[0068]

[0069] When k n =1, k m = 1, the maximum unambiguous range R of the radar can be obtained max and the maximum unambiguous angle θ max , respectively expressed as:

[0070]

[0071] It can be seen that the maximum unambiguous distance and maximum unambiguous angle of the radar are related to the frequency offset and the set coprime number. A small maximum unambiguous range will lead to distance and angle ambiguity when estimating target parameters, which is not conducive to accurately determining the target position.

[0072] In this embodiment, the frequency offset of the first subarray is Q1Δf, the number of array elements is N1, the frequency offset of the second subarray is Q2Δf, the number of array elements is 2N-N1, then the transmission frequency f of the nth transmitting array element is n It can be expressed as:

[0073]

[0074] At the receiving end, the frequency compensation between different elements of the receiving array keeps PΔf unchanged, and Q1, Q2 and P are relatively prime integers. The above scheme can eliminate the distance and angle coupling and effectively solve the distance and angle ambiguity problems that occur when estimating target parameters.

[0075] The following example uses a target distance and angle of 0.5 km and 10° as examples. It should be noted that the target distance and angle described in this article are the reference distance and angle of the target distance transmitting array. The corresponding parameters of the dual coprime FDA-MIMO (Subarrays Dual Coprime Frequency Diverse Array Multiple-InputMultiple-Output, SDCFDA-MIMO) radar including two subarrays are: N=2, M=3, Δf=4kHz, P=4, Q1=3, Q2=5, N1=2. The target estimation result of the SDCFDA-MIMO radar is shown in the color representation gain, as shown in the figure. Figure 5 A schematic diagram of a target estimation spectrum of a SDCFDA-MIMO radar provided in an embodiment of the present application, it should be noted that: Figure 5-Figure 11 The color of the target estimation spectrum indicates the gain size. From blue to yellow on the right side of the color bar, the gain increases from small to large. When the gain is blue, it means that the target is not recognized. It can be seen that Figure 5 The target estimation spectrum in has only one target peak point, indicating that the SDCFDA-MIMO radar including two sub-arrays can effectively eliminate distance and angle ambiguity.

[0076] In the above scheme, the radar's transmitting array is divided into two sub-arrays, namely the first sub-array and the second sub-array, and different frequency offsets are set for each sub-array. Furthermore, the distance and angle coupling phenomenon can be eliminated, and the distance and angle ambiguity problems that occur during target parameter estimation can be effectively solved, so that more detection targets can be correctly distinguished and the target resolution capability can be improved.

[0077] In some embodiments, the transmit array includes a third sub-array, the frequency deviation coefficient of the third sub-array is Q3, and Q3 and P are coprime integers.

[0078] The transmitting array of the radar includes only one subarray, namely the third subarray. The frequency deviation coefficient of the third subarray is Q3, and Q3 and P are coprime integers.

[0079] In the above scheme, the transmitting array of the radar includes only one subarray. By introducing frequency compensation at the receiving array end, a virtual frequency deviation can be generated after matched filtering, thereby improving the freedom of the radar in the frequency dimension. When performing subsequent target parameter estimation, the radar can perform multiple sampling to obtain multi-snapshot signals, thereby ensuring the applicability of the subspace algorithm. Compared with the traditional coprime FDA-MIMO radar, the radar will not encounter the problem of single-snapshot parameter estimation when estimating target parameters, thereby improving the universality of the practical application of the radar array.

[0080] In some embodiments, the transmission signal of the nth transmission array element is expressed by the following formula:

[0081] Among them, s n (t) is the transmit signal, n is the index of the transmit array element, n=0, 1, ..., 2N-1, E is the total power of the transmit signal of the transmit array, ψ n (t) is the baseband modulation signal corresponding to the transmit signal of the nth transmit array element, j is an imaginary unit, f0 is the carrier frequency of the transmit signal of the transmit array, Δf is the unit frequency deviation, and T is the pulse duration of the transmit signal of the transmit array.

[0082] In the above scheme, the frequency offset between different transmitting array elements is Q3Δf, and the radar system realizes frequency diversity, thereby increasing the system's degree of freedom in the frequency dimension. The baseband modulation signal is designed to meet the orthogonal condition, and the signals of different transmitting array elements are orthogonal in time, which helps to separate and process the signals of each transmitting array element at the receiving array end, thereby improving the efficiency and accuracy of signal processing.

[0083] In some embodiments, the received signal of the mth receiving element is expressed by the following formula:

[0084]

[0085] Among them, y m (t) is the received signal, m is the index of the receiving array element, m=0, 1, ..., M-1, ξ is the complex reflection coefficient of the detection target, τ n,m It is the time required for the echo signal emitted by the nth transmitting element to be captured by the mth receiving element.

[0086] For a far-field target at a distance and angle of (r0, θ0), the receiving signal model provided in this embodiment can be used to represent the target echo signal received by the mth receiving array element.

[0087] τ n,m The expression is:

[0088]

[0089] in,

[0090] Under the far-field narrowband assumption, the received signal model can be expressed as;

[0091]

[0092] Among them, when When , the approximate relationship in the above formula holds.

[0093] The processing unit combines the received signal in the above formula with After mixing, the mixed signal can be obtained:

[0094]

[0095] In the above scheme, the receiving signal model takes into account the interaction between different transmitting array elements n and different receiving array elements m to achieve joint estimation of angle and distance. Since the received signal contains the frequency offset Q3Δf between different transmitting array elements, the radar can improve the resolution of angle and distance through frequency diversity, thereby enhancing the target recognition and resolution capabilities.

[0096] In some embodiments, the target signal obtained after frequency compensation of the received signal corresponding to the mth receiving array element is expressed by the following formula:

[0097]

[0098] in, is the target signal, r0 is the distance parameter of the detection target, θ0 is the angle parameter of the detection target, and c is the speed of light.

[0099] By mixing the frequency signal of the mth receiving element in the above embodiment Perform frequency compensation to obtain the compensated signal

[0100] Then, the signal after compensation of the mth receiving element is Transmitted to 2N channels and respectively n,m (t) performs matched filtering, φ n,m The expression of (t) is:

[0101] φ n,m (t) = ψ n (t)e -j2π(nQΔf+mPΔf)t ;

[0102] After matched filtering, the expression of the transmitted signal of the nth transmitting array element received by the mth receiving array element is:

[0103]

[0104] Where v represents the complex coefficient after matched filtering.

[0105] For I distances and angles, respectively, i and θ i For a far-field target with (i=1,2,…,I), the I target echo signals are matched filtered at the receiving end. At time t, the echo signals of the 2NM virtual channels after matched filtering can be stacked into a vector Its expression is:

[0106]

[0107] Among them, a dc (θ i ,r i ) is the array steering vector of the i-th target, and denote the transmitting and receiving steering vectors of the i-th target, respectively, and n dc (t) is Gaussian noise, A dc =[adc (θ1,r1),…,a dc (θ I ,r I )] is the array steering vector matrix of I targets, c(t)=[η1(t),…,η I (t)] T is the target reflection coefficient vector. and The expressions are:

[0108]

[0109] in, and represent the transmitting frequency and receiving frequency of the i-th target respectively, and The expressions are:

[0110]

[0111] Assuming the number of sampling snapshots is L, the sampling covariance matrix of the echo signal can be expressed as:

[0112]

[0113] in,(·) H Represents the conjugate transpose operation.

[0114] Then, according to the sampling covariance matrix, a subspace-based algorithm can be used to estimate the target parameters.

[0115] In the above scheme, through frequency compensation, the interference caused by Doppler expansion can be reduced, making the received signal more concentrated in the Doppler dimension. In addition, different channel signals can achieve coherent accumulation and enhance the coherence of the signal, thereby improving the radar's detection capability for targets and improving the radar's spatial resolution and target positioning accuracy.

[0116] In some embodiments, the processing unit is further used to estimate the angle and distance parameters of the detected target according to the received signal corresponding to the transmitted signal of each transmitting array element received by each receiving array element through a subspace algorithm.

[0117] The present application provides a radar parameter estimation method, which is applied to a processing unit in the radar described in any of the above embodiments. The radar parameter estimation method includes:

[0118] Step S10: frequency compensation is performed on the mixing signal corresponding to each receiving array element, wherein the mixing signal is obtained by mixing the receiving signal received by the receiving array element, the frequency compensation value of the mth receiving array element is mP times the unit frequency deviation, and the frequency deviation coefficient and P are coprime integers.

[0119] Step S20: Estimate the angle and distance parameters of the detected target according to the received signal corresponding to the transmitted signal of each transmitting array element received by each receiving array element through a subspace algorithm.

[0120] In a possible implementation, a 2D-MUSIC algorithm in a subspace algorithm may be used to estimate the angle and distance parameters of the detection target.

[0121] In traditional mutually prime FDA-MIMO radars, due to the limitations of frequency offset and array structure, only a single snapshot can be used for target parameter estimation, which limits the radar performance. In the above scheme, by introducing frequency compensation that is mutually prime with the frequency offset of the transmitting array at the receiving array end, the radar can use the multi-snapshot algorithm to estimate the target parameters and improve the performance of target parameter estimation.

[0122] In order to better illustrate the beneficial effects of the present application, the following Table 1 compares the number of array elements, array element spacing, frequency offset, frequency compensation and array / frequency degrees of freedom of different arrays, including uniform arrays and uniform frequency offset (Uniform Linear Arrays and Uniform Frequency Offsets, ULA-UFO) FDA-MIMO, uniform arrays and coprime frequency offset (Uniform Linear Arrays and Coprime Frequency Offsets, ULA-CFO) FDA-MIMO, coprime arrays and uniform frequency offset (Coprime Linear Arrays and Uniform Frequency Offsets, CLA-UFO) FDA-MIMO and the dual coprime (Dual Coprime, DC) FDA-MIMO radar provided in the present application.

[0123]

[0124] Table 1 Comparison of structures and performance of different arrays

[0125] The degrees of freedom listed in Table 1 are all the degrees of freedom after the matched filtering of the received signal, so as to ensure that the multi-snap algorithm can be used for target parameter estimation. Since the CLA-CFO array improves the frequency dimension degrees of freedom by vectorizing the covariance matrix and cannot use the subspace algorithm for target parameter estimation, no comparison is made. It can be seen that the DCFDA-MIMO array provided in the embodiment of the present application has a higher degree of freedom than the other array structures, and thus can obtain better distance estimation performance and a larger maximum number of detectable targets.

[0126] In order to verify the beneficial effects of the SDCFDA-MIMO radar array of the embodiment of the present application, the following simulation experiments were conducted:

[0127] Exemplarily, the simulation experiment can be performed using the radar system parameters in Table 2 below.

[0128] Simulation parameters symbol Value Carrier frequency <![CDATA[f0]]> 10GHz Transmitted signal wavelength λ 0.03m Unit element spacing d 0.015m Unit frequency deviation Δf 4kHz Snapshots L 128 Signal-to-Noise Ratio SNR 20dB

[0129] Table 2 Radar simulation parameters

[0130] During the simulation, the array parameters of the SDCFDA-MIMO radar are N=2, M=3, P=7, Q1=3, Q2=5. For comparison, the three radar arrays of ULA-UFO, ULA-CFO, and CLA-UFO use the array structures corresponding to Table 1. The simulation uses the 2D-MUSIC algorithm for target parameter estimation.

[0131] Simulation experiment 1: Resolution performance comparison

[0132] Refer to Figure 6, which is a schematic diagram of the first result of the resolution performance comparison simulation experiment provided in an embodiment of the present application. When two incoherent targets have the same distance and different angles, and are located at (10°, 2km) and (10°, 2.3km) respectively, Figure 6 (a)-(d) show the two-dimensional estimated spectra of the SDCFDA-MIMO, CLA-UFOFDA-MIMO, ULA-CFOFDA-MIMO, and ULA-UFOFDA-MIMO arrays, respectively, and Figure 6 (e) shows the distance dimension profile of different arrays.

[0133] Refer to Figure 7, which is a schematic diagram of the second result of the resolution performance comparison simulation experiment provided in an embodiment of the present application. When two incoherent targets have different distances and the same angle, and are located at (10°, 2km) and (13°, 2km) respectively, Figure 7 (a)-(d) show the two-dimensional estimated spectra of the SDCFDA-MIMO, CLA-UFOFDA-MIMO, ULA-CFOFDA-MIMO, and ULA-UFOFDA-MIMO arrays, and Figure 7 (e) shows the angular dimension profile of different arrays.

[0134] It can be seen from Figures 6 and 7 that the SDCFDA-MIMO radar array provided by the present application can effectively distinguish two targets in both cases. CLA-UFO adopts a sparse array structure, so it can distinguish two targets at the same distance and different angles, but cannot distinguish two targets at a closer distance. ULA-CFO and ULA-UFO cannot correctly distinguish two targets in both scenarios.

[0135] Referring to Figure 8, Figure 8 is a schematic diagram of the third result of the resolution performance comparison simulation experiment provided in the embodiment of the present application. When the positions of the six incoherent targets are (10°, 2km), (10°, 2.4km), (-15°, 3km), (-15°, 3.4km), (0°, 4km), and (5°, 4km), Figure 8 (a)-(d) shows the two-dimensional estimated spectrum of the SDCFDA-MIMO, CLA-UFOFDA-MIMO, ULA-CFOFDA-MIMO, and ULA-UFOFDA-MIMO arrays. It can be seen that the SDCFDA-MIMO radar in the embodiment of the present application has the ability to distinguish targets simultaneously in the angle and distance dimensions. In contrast, CLA-UFO can only distinguish two targets with close angles through the array degrees of freedom, and cannot distinguish two targets with close distances. However, due to the lack of sufficient degrees of freedom, ULA-CFO and ULA-UFO cannot accurately estimate the position information of the target.

[0136] Comprehensive simulation experiment 1 can prove that the SDCFDA-MIMO radar array in the embodiment of the present application has better resolution capability.

[0137] Simulation experiment 2: Array degree of freedom comparison

[0138] Refer to Figure 9, which is a schematic diagram of the results of the array degree of freedom comparison simulation experiment provided in an embodiment of the present application. In the simulation experiment, the number of snapshots is set to 2000 and the signal-to-noise ratio is 20dB. Figure 9 (a)-(d) shows the two-dimensional estimated spectra of 10 incoherent targets of the SDCFDA-MIMO, CLA-UFOFDA-MIMO, ULA-CFOFDA-MIMO, and ULA-UFOFDA-MIMO arrays. It can be seen that compared with the other three array structures, the SDCFDA-MIMO radar array can correctly distinguish 10 incoherent targets, proving the advantage of the SDCFDA-MIMO radar array in terms of the maximum number of resolvable targets.

[0139] In addition, in order to prove the effect of introducing frequency compensation at the receiving array end on improving the distance dimension freedom, this simulation experiment also applies the frequency compensation scheme to the ULA-UFO array. Referring to Figure 10, Figure 10 shows a schematic diagram of the two-dimensional estimated spectrum of the ULA-UFO array without applying frequency compensation. Figures 10(a) and 10(a) are the two-dimensional estimated spectra of two and five incoherent targets. For two incoherent targets, the positions are (10°, 1km) and (10°, 2km), respectively. For five incoherent targets, the positions are (10°, 1km), (10°, 2km), (10°, 3km), (10°, 4km), and (10°, 5km), respectively. Fig.11 , Fig.11 A schematic diagram of the two-dimensional estimated spectrum after frequency compensation is applied to the ULA-UFO array, where the positions of the five incoherent targets are (10°, 1 km), (10°, 2 km), (10°, 3 km), (10°, 4 km), and (10°, 5 km).

[0140] Comprehensive Figure 10 Fig.11 It can be seen that the ULA-UFO array without frequency compensation can correctly distinguish two targets, indicating that its frequency deviation bandwidth is sufficient to distinguish two incoherent targets 1 km apart, but it cannot correctly distinguish five incoherent targets 1 km apart, indicating that the frequency dimension freedom of the ULA-UFO array without frequency compensation does not support parameter estimation for five targets. The ULA-UFO array after frequency compensation can correctly distinguish five incoherent targets, proving that frequency compensation can effectively increase the freedom of the distance dimension of the radar array.

[0141] Simulation experiment 3: Comparison of distance and angle estimation performance

[0142] Referring to FIG. 12 , FIG. 12 is a schematic diagram of the results of a simulation experiment comparing the distance and angle estimation performance provided in an embodiment of the present application. In the experiment, the positions of the two incoherent targets are (-5°, 0.7 km) and (5°, 3 km), respectively. The number of Monte Carlo simulations is 2000 times, and the root mean square error (RMSE) of the distance and angle estimation is used to evaluate the angle and distance estimation performance of different arrays. The RMSE of the distance estimation is r and RMSE of angle estimation θ The expressions are:

[0143]

[0144] Among them, T e is the number of Monte Carlo simulations, and They represent the angle and distance estimates of the i-th target in the k-th Monte Carlo simulation respectively.

[0145] Figures 12(a) and 12(b) show the RMSE performance of distance and angle estimation of different arrays at different signal-to-noise ratios and the Cramér-Rao Bound (CRB) when the number of snapshots is 256, respectively. Figures 12(c) and 12(d) show the RMSE performance of distance and angle estimation of different arrays at different number of snapshots and the CRB when the signal-to-noise ratio is 20dB. From Figures 12(a) and 12(c), it can be seen that the distance dimension estimation performance of the SDCFDA-MIMO radar array is significantly better than that of the other three arrays, thus verifying the superiority of the SDCFDA-MIMO radar array in distance dimension estimation; from Figures 12(b) and 12(d), it can be seen that the angle estimation performance of the SDCFDA-MIMO radar array and the CLA-UFO array is similar and better than the other two arrays.

[0146] The present application provides a computer program product, including computer program instructions, which, when read and executed by a processor, execute the method provided by the above method embodiment.

[0147] The present application provides a computer-readable storage medium, including: the computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the method provided by the above method embodiment.

[0148] Fig.13 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application, such as Fig.13 As shown, the electronic device includes: a processor 131, a memory 132 and a bus 133; wherein the processor 131 and the memory 132 communicate with each other through the bus 133; the memory 132 stores program instructions that can be executed by the processor 131, and the processor 131 calls the program instructions to execute the method provided by the above method embodiment.

[0149] The processor 131 includes one or more (only one is shown in the figure), which can be an integrated circuit chip with signal processing capabilities. The above-mentioned processor 131 can be a general-purpose processor, including a central processing unit (CPU), a micro control unit (MCU), a network processor (NP) or other conventional processors; it can also be a dedicated processor, including a neural network processor (NPU), a graphics processor (GPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. In addition, when there are multiple processors 131, some of them can be general-purpose processors and the other part can be dedicated processors.

[0150] The memory 132 includes one or more (only one is shown in the figure), which may be, but not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The processor 131 and other possible components may access the memory 132 and read and / or write data therein.

[0151] In particular, one or more computer program instructions may be stored in the memory 132 , and the processor 131 may read and execute these computer program instructions to implement the weak password scanning behavior identification method provided in the embodiment of the present application.

[0152] The bus 133 includes one or more (only one is shown in the figure), which can be used to communicate directly or indirectly with other devices to interact with data. The bus 133 may include devices for wired and wireless communication, such as optical fiber, serial peripheral interface (Serial Peripheral Interface, referred to as SPI) module, integrated circuit bus (Inter-Integrated Circuit, referred to as I2C), etc., and may also include devices for wireless communication, such as Bluetooth module, Wi-Fi module, mobile communication module (such as 4G, 5G module), etc.

[0153] Understandably, Fig.13 The structure shown is for illustration only. The electronic device may also include Fig.13 More or fewer components as shown, or with Fig.13 Different structures are shown. Fig.13 The components shown in the figure can be implemented by hardware, software or a combination thereof. The electronic device may be a physical device, such as a switch, a router, a server, a PC, etc., or a virtual device, such as a virtual machine, a virtualized container, etc. Moreover, the electronic device is not limited to a single device, but may also be a combination of multiple devices or an integrated environment composed of a large number of devices.

[0154] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0155] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0156] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0157] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A radar, characterized in that: include: A transmitting array, a receiving array and a processing unit, wherein the processing unit is connected to the receiving array; The number of transmitting elements in the transmitting array is 2N, and the spacing between the transmitting elements is Md, the number of receiving elements in the receiving array is M, and the spacing between the receiving elements is Nd, wherein N and M are coprime integers, and d is the unit element spacing; The transmitting array includes at least one sub-array, each sub-array includes at least one transmitting array element, and the frequency offset of each sub-array is configured as the product of a unit frequency offset and a frequency offset coefficient; The processing unit is used to perform frequency compensation on a mixing signal corresponding to each receiving array element, wherein the mixing signal is obtained by mixing a receiving signal received by the receiving array element, the frequency compensation value of the mth receiving array element is mP times the unit frequency deviation, and the frequency deviation coefficient and P are coprime integers.

2. The radar according to claim 1, characterized in that The transmitting array includes a first sub-array and a second sub-array. The frequency offset coefficient of the first sub-array is Q1, the frequency offset coefficient of the second sub-array is Q2, and Q1, Q2 and P are coprime integers.

3. The radar according to claim 1, characterized in that: The transmitting array includes a third subarray, the frequency deviation coefficient of the third subarray is Q3, and Q3 and P are coprime integers.

4. The radar according to claim 3, characterized in that: The transmission signal of the nth transmitting array element is expressed by the following formula: Among them, s n (t) is the transmit signal, n is the index of the transmit array element, n=0, 1, ..., 2N-1, E is the total power of the transmit signal of the transmit array, ψ n (t) is the baseband modulation signal corresponding to the transmit signal of the nth transmit array element, j is an imaginary unit, f0 is the carrier frequency of the transmit signal of the transmit array, Δf is the unit frequency deviation, and T is the pulse duration of the transmit signal of the transmit array.

5. The radar according to claim 4, characterized in that: The received signal of the mth receiving element is expressed by the following formula: Among them, y m (t) is the received signal, m is the index of the receiving array element, m=0,…,M-1, ξ is the complex reflection coefficient of the detected target, τ n,m It is the time required for the echo signal emitted by the nth transmitting element to be captured by the mth receiving element.

6. The radar according to claim 5, characterized in that: The target signal obtained after frequency compensation of the received signal corresponding to the mth receiving array element is expressed by the following formula: in, is the target signal, r0 is the distance parameter of the detection target, θ0 is the angle parameter of the detection target, and c is the speed of light.

7. The radar according to any one of claims 1 to 6, characterized in that: The processing unit is also used to estimate the angle and distance parameters of the detection target according to the received signal corresponding to the transmitted signal of each transmitting array element received by each receiving array element through a subspace algorithm.

8. A radar parameter estimation method, characterized in that: Applied to a processing unit in a radar according to any one of claims 1 to 6, the radar parameter estimation method comprising: Performing frequency compensation on a mixing signal corresponding to each receiving array element, wherein the mixing signal is obtained by mixing a receiving signal received by the receiving array element, the frequency compensation value of the mth receiving array element is mP times the unit frequency deviation, and the frequency deviation coefficient and P are coprime integers; The angle and distance parameters of the detected target are estimated through a subspace algorithm based on the received signal corresponding to the transmitted signal of each transmitting array element received by each receiving array element.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to claim 7 is executed.

10. A computer program product, characterized in that include: A computer program for executing the method according to claim 7 when the computer program is executed by a processor.

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