A method for resisting main lobe deception jamming of space-time coded array radar

Abstract

The application discloses a method for resisting main lobe deceptive jamming of space-time coding array radar, comprising the following steps: transmitting orthogonal linear frequency modulation signals; receiving echo signals to obtain the echo signals after frequency conversion of each receiving array element; performing mixing and matching filtering processing on the echo signals after frequency conversion to obtain the echo signals after matching filtering, and obtaining a transmitting steering vector and a receiving steering vector; obtaining the transmitting spatial frequency and the receiving spatial frequency of a real target and a false target; obtaining the transmitting spatial frequency difference between the real target and the false target; performing distance compensation on the echo signals to obtain the transmitting spatial frequency difference between the real target and the false target after distance compensation; designing a transmitting-receiving two-dimensional beamformer according to the transmitting spatial frequency difference after distance compensation, and suppressing the false target in the echo signals. The application obtains an additional degree of freedom in the distance dimension, and can suppress the false target generated by the main lobe deceptive jamming according to the difference between the real target and the false target in the transmitting spatial frequency.

Description

Technical Field

[0001] This invention belongs to the field of array radar signal processing technology, specifically relating to a method for resisting main lobe deception interference in space-time coded array radar, which can be used to distinguish between real and false targets. Background Technology

[0002] Today, radars face increasingly complex electromagnetic environments, and various jamming methods are emerging. Among them, deceptive jamming induces radar to mistake false targets for real targets by radiating electromagnetic waves that resemble the echoes of real targets. This leads to the loss of real targets, the occupation of radar resources, and abnormal air situations, causing a sharp deterioration in radar system performance. In particular, when deceptive jamming originates from the main lobe direction, the jamming has a greater impact on the power and survivability of the radar system.

[0003] Currently, scholars both domestically and internationally have conducted some research on deceptive interference from the main lobe direction, but no method exists to distinguish targets from deceptive interference with sufficiently high resolution in both the spatial and temporal domains. In fact, traditional radar systems struggle to effectively suppress main lobe deceptive interference. Existing literature indicates that Frequency Diversity Array (FDA) radars possess the ability to resist main lobe deceptive interference by mining multi-parameter information of both targets and interference. Based on FDA radar, scholars have conducted the following research: Xu Jingwei was the first to suppress main lobe interference using two-dimensional adaptive beamforming technology within the FDA radar system. Tan Qingli replaced linear frequency offset with logarithmic frequency offset, breaking the periodicity of the radiation pattern and weakening the influence of interference near the grating lobe, but neglecting the storage modulation delay during the interference signal generation process. Xu Jingwei further improved the model by using subspace projection for sample selection, achieving effective suppression of main lobe deceptive interference. ABDALLA et al. divided the frequency diversity array into two subarrays with different frequency steps, achieving interference discrimination and suppression at the subarray level by jointly considering range, angle, and Doppler domains. However, this method, using ideal orthogonal waveforms, is difficult to implement in engineering applications. Lan Lan et al. conducted research on interference suppression under non-ideal orthogonal waveform conditions, designing a range-angle two-dimensional adaptive filter, which effectively suppressed false targets. It is evident that most existing research on anti-jamming for waveform diversity arrays is based on frequency diversity array radars, with very few based on space-time coded array radars. However, space-time coded arrays are easier to implement in engineering compared to frequency diversity arrays. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a method for resisting main lobe deception interference in space-time coded array radar.

[0005] This invention provides a method for resisting main lobe deception jamming in space-time coded array radar, comprising:

[0006] S1: Transmit orthogonal linear frequency modulated signals using STCA-MIMO radar;

[0007] S2: Receive echo signals, perform down-conversion processing on the echo signals received by each receiving array element, and obtain the down-converted echo signals of each receiving array element.

[0008] S3: Perform mixing and matched filtering on the down-converted echo signal of each receiving array element to obtain the matched filtered echo signal, and obtain the transmit steering vector and receive steering vector;

[0009] S4: Based on the expressions for the transmit steering vector and the receive steering vector, obtain the transmit spatial frequency and receive spatial frequency of the real target and the dummy target;

[0010] S5: Based on the transmitted spatial frequency and the received spatial frequency, obtain the difference in transmitted spatial frequencies between the real target and the false target;

[0011] S6: Perform range compensation on the echo signal after matched filtering, and obtain the transmission spatial frequency difference between the real target and the false target after range compensation;

[0012] S7: Design a transmit-receive two-dimensional beamformer based on the distance-compensated transmit spatial frequency difference, and suppress false targets in the echo signal.

[0013] In one embodiment of the present invention, S1 includes:

[0014] S1.1: Transmitting orthogonal linear frequency modulated signals using STCA-MIMO radar, wherein the signal s transmitted by the m-th transmitting element after a time delay. m (t) is

[0015]

[0016] Where f0 is the carrier frequency, Δt is the time delay between transmitted signals on adjacent transmit array elements, and c m g(t) is the orthogonal coded signal of the m-th transmitting element, and g(t) is the linear frequency modulated signal;

[0017] S1.2: Under the narrowband signal assumption, obtain the signal representation of the m-th transmitting element when it reaches the target:

[0018]

[0019] in, This represents the time delay of the signal transmitted by the m-th transmitting element. The first transmitting element represents the one-way delay of the signal transmitted, d is the distance between transmitting elements, c is the speed of light, t is time, and θ0 is the angle of the target.

[0020] In one embodiment of the present invention, S2 includes:

[0021] S2.1: Obtain the echo signal received by the nth receiving element from the mth transmitting element;

[0022] S2.2: The echo signals from the m transmitting elements are superimposed to obtain the echo signal received by the nth receiving element from all M transmitting elements:

[0023]

[0024] Where λ is the wavelength and μ is the frequency modulation slope of the linear frequency modulated signal;

[0025] S2.3: Perform down-conversion processing on the echo signals from all M transmitting array elements to obtain the down-converted echo signals:

[0026]

[0027] in, For complex envelope.

[0028] In one embodiment of the present invention, S3 includes:

[0029] S3.1: Perform digital mixing on the echo signal received by each receiving array element, which is related to the time delay Δt, to obtain the digitally mixed echo signal:

[0030]

[0031] S3.2: The matched filter designed for the transmitted signal of the m-th transmitting element is as follows:

[0032]

[0033] The superscript * indicates the conjugate operation;

[0034] S3.3: Obtain the signal after the echo signal received by the nth receiving element passes through the m-th dimension matched filter.

[0035]

[0036] S3.4: Obtain the signal y of the target echo received by the nth receiving element after passing through the M-dimensional matched filter. n (t,θ0):

[0037]

[0038] S3.5: The signal after passing the received signals of all N receiving array elements through an M-dimensional matched filter can be represented as an MN×1-dimensional column vector:

[0039]

[0040] in, Let represent the Kronecker product operation, where b(θ0) is the receive steering vector and a(R0,θ0) is the equivalent transmit steering vector.

[0041]

[0042]

[0043] In one embodiment of the present invention, S4 includes:

[0044] S4.1: Based on the expressions for the transmission steering vector and reception steering vector of the real target, obtain the transmission spatial frequency f of the real target. T and the received spatial frequency f R :

[0045]

[0046]

[0047] Where R0 represents the distance between the real target and the radar;

[0048] S4.2: Obtain the launch spatial frequency of the q-th dummy target. and received space frequency

[0049]

[0050]

[0051] Among them, R q This represents the distance between the q-th dummy target and the radar.

[0052] In one embodiment of the present invention, S5 includes:

[0053] S5.1: When distance ambiguity exists, the true distance of the real target is represented as:

[0054] R0 = r0 + (p-1)R u ,

[0055] Where r0 is the principal distance to the true target. For the maximum unambiguous distance, fr The pulse repetition frequency, The distance to the real target is the fuzzy number, and int(·) represents the operation of using the tail-removal method to obtain a numerical approximation;

[0056] S5.2: Obtain the equivalent actual distance to the q-th false target:

[0057] R q =r q +(p′-1)R u ,

[0058] Where, r q Let be the principal distance of the q-th pseudo-target. Let be the distance blur number of the q-th false target;

[0059] S5.3: Obtain the true target and the q-th false target using R u The spatial frequency difference of the transmission interval:

[0060]

[0061] in, The part is the non-negative integer part, and v∈[0,1) is the positive decimal part.

[0062] In one embodiment of the present invention, S6 includes:

[0063] S6.1: Construct a compensation function based on the principal distance of the true target. And construct the distance compensation vector g:

[0064]

[0065] Among them, 1 N×1 Represents a column vector of all 1s. For the emission domain compensation vector;

[0066] S6.2: Use the distance compensation vector to perform distance compensation on the echo signal after passing through the M-dimensional matched filter to obtain the distance-compensated received signal:

[0067]

[0068] Where ⊙ represents the Hadema product;

[0069] S6.3: Obtain the range-compensated launch spatial frequencies of the real target and the q-th false target:

[0070]

[0071]

[0072] in, The transmission spatial frequency after distance compensation. r is the received spatial frequency after distance compensation. Δ =r q -r0 represents the remaining principal value distance after distance compensation;

[0073] S6.4: Obtain the spatial frequency difference between the real target and the dummy target after range compensation:

[0074]

[0075] In one embodiment of the present invention, S7 includes:

[0076] S7.1: Obtaining the optimization problem using a linearly constrained minimum variance beamformer:

[0077]

[0078] Where w represents the weight vector, (·) H For the conjugate transpose operation, R j+n The expressions for the interference plus noise covariance matrix, C and F are:

[0079] C=[u(R0,θ0),u(R0,θ0-Δθ),u(R0,θ0+Δθ)],

[0080] F = [1,1,1] T ,

[0081] Where u(R0,θ0) is the virtual guidance vector of the real target. Δθ represents the angular offset of the actual target;

[0082] S7.2: Obtain the optimal weight vector using the aforementioned optimization problem:

[0083]

[0084] S7.3: Use the optimal weight vector to suppress the false target signal in the range-compensated received signal to obtain the suppressed signal.

[0085] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0086] 1. This invention proposes a method for resisting main lobe deception interference in space-time coded array radar. Compared with traditional MIMO radar, it gains additional degrees of freedom in the range dimension and can suppress false targets generated by main lobe deception interference based on the difference between real and false targets in the transmission space frequency.

[0087] 2. This invention adopts a novel waveform diversity radar system with a space-time coded array, which introduces a time delay difference between different array elements. Compared with the frequency stepping design of FDA-MIMO radar, the time delay introduced by the space-time coded array is simpler to implement in engineering. At the same time, at the receiving end, only a single antenna can be used to form the equivalent transmit beam, which increases the degree of freedom of the transmit dimension.

[0088] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0089] Figure 1 This is a flowchart illustrating the implementation of a method for resisting main lobe deception interference in a space-time coded array radar, as provided in an embodiment of the present invention.

[0090] Figure 2 This is a schematic diagram of the array structure of an STCA-MIMO radar provided in an embodiment of the present invention;

[0091] Figure 3 It is a range-angle slice of the transmission pattern of a conventional MIMO radar;

[0092] Figure 4 This is a range-angle slice of the STCA-MIMO radar transmit pattern;

[0093] Figure 5 This is a power spectrum diagram of real and false targets distributed by a conventional MIMO radar;

[0094] Figure 6 This is the power spectrum diagram of the STCA-MIMO radar for real and false targets;

[0095] Figure 7 This is the LCMV beamformer response diagram of the STCA-MIMO radar;

[0096] Figure 8 This is a comparison chart of pulse compression results for real and false targets by conventional MIMO radar and STCA-MIMO radar. Detailed Implementation

[0097] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following describes in detail the method for resisting main lobe deception interference in space-time coded array radar according to the present invention, in conjunction with the accompanying drawings and specific embodiments.

[0098] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0099] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes said element.

[0100] Space-Time Coded Array (STCA) radar is a novel waveform diversity radar system. Its principle model is based on an equidistant uniform linear array, introducing a fixed time delay between adjacent elements. This time delay is much smaller than the pulse duration. By transmitting orthogonally coded frequency-modulated signals at different times, orthogonality of the transmitted signals between elements can be achieved. By combining STCA with Multiple-Input Multiple-Output (MIMO) technology, the transmitted waveforms from different transmitting elements can be separated at the receiver to obtain a range-angle-dependent transmission steering vector, thus gaining an additional degree of freedom in the range dimension.

[0101] Please see Figure 1 , Figure 1 This is a flowchart illustrating the implementation of a method for resisting main lobe deception interference in a space-time coded array radar according to an embodiment of the present invention. The method includes:

[0102] S1: Transmit orthogonal linear frequency modulated signals using STCA-MIMO radar.

[0103] In this embodiment, step S1 specifically includes:

[0104] S1.1: Transmit orthogonal linear frequency modulated signals using STCA-MIMO radar.

[0105] Specifically, suppose the STCA-MIMO radar is a co-located MIMO radar system consisting of M transmitting elements and N receiving elements. Both the transmitting and receiving arrays are uniformly spaced linear arrays, and the spacing between the transmitting and receiving elements is half a wavelength. The M transmitting elements transmit orthogonal linear frequency modulated signals, and there is a relative time delay between each transmitting element. The radar transmits space-time coded baseband waveforms.

[0106] Please see Figure 2 , Figure 2 This is a schematic diagram of an STCA-MIMO radar array structure provided by an embodiment of the present invention. The scenario used in this embodiment involves a one-dimensional equidistant linear array transmitting orthogonal space-time coded signals: it consists of M identical omnidirectional transmitting elements and N identical omnidirectional receiving elements, with the spacing between adjacent elements being half a wavelength. All transmitting elements transmit orthogonal signals.

[0107]

[0108] in, Let g(t) represent the signal transmitted by the m-th transmitting element, and g(t) be a linear frequency modulated signal. m (t) represents the orthogonal coded signal of the m-th transmitting element, where t represents time.

[0109]

[0110]

[0111] in, For pulse gate function, T p Where B is the pulse width of the transmitted signal, and B is the bandwidth of the transmitted signal, μ = B / T p Let be the frequency modulation slope of the linear frequency modulated signal, and t represent time. According to... And g(t) can then be used to solve for c. m (t).

[0112] There is a time delay Δt between the transmission times of signals transmitted on adjacent transmitting elements. Taking the first transmitting element as a reference, the signal s transmitted by the m-th transmitting element after the time delay can be obtained. m (t) is:

[0113]

[0114] Where f0 represents the carrier frequency, Δt represents the time delay between the transmitted signals on adjacent transmitting elements, and g(t-(m-1)Δt) is the linear frequency modulated signal of the m-th transmitting element.

[0115] S1.2: Under the narrowband signal assumption, obtain the signal representation of the m-th transmitting element of the STCA-MIMO radar when it reaches the target.

[0116] Suppose there exists a point target in the far field with an angle of θ0 and a distance of R0 from the STCA-MIMO radar. Then, the signal transmitted by the m-th transmitting element of the STCA-MIMO radar when it reaches the target can be expressed as:

[0117]

[0118] in, This represents the time delay of the signal transmitted by the m-th transmitting element. d represents the one-way time delay of the signal emitted by the first transmitting element, which is the time delay from the transmitter to the target. d is the distance between the transmitting elements, and c is the speed of light.

[0119] Under the narrowband signal assumption, the above equation can be written as

[0120]

[0121] S2: Receive the echo signal from the STCA-MIMO radar, perform down-conversion processing on the echo signal received by each receiving element, and obtain the down-converted echo signal of each receiving element.

[0122] In this embodiment, S2 specifically includes:

[0123] S2.1: If the receiving array is a conventional MIMO, then the signal received by the nth receiving element from the mth transmitting element in the STCA-MIMO radar is:

[0124]

[0125] in, λ represents the one-way delay of the signal from the target to the receiving array element, and λ represents the wavelength.

[0126] S2.2: The echo signals from the m transmitting elements are superimposed to obtain the echo signal received by the nth receiving element from all M transmitting elements:

[0127]

[0128] in, This represents the expression for the signal transmitted by the m-th transmitting element after a two-way delay.

[0129] S2.3: Down-convert the echo signals from all M transmitting elements (i.e., down-convert by multiplying by ). ), to obtain the echo signal after down-conversion:

[0130]

[0131] in, For complex envelope.

[0132] S3: Perform mixing and matched filtering on the down-converted echo signal of each receiving array element to obtain the matched filtered echo signal, and obtain the transmit steering vector and receive steering vector.

[0133] S3.1: The echo signal received by each receiving element of the STCA-MIMO radar needs to be processed by an M-dimensional filter. Digital mixing, which is related to the time delay Δt, is performed on the echo signal received by each receiving element to obtain the digitally mixed echo signal.

[0134]

[0135] S3.2: The matched filter designed for the transmitted signal of the m-th transmitting element is as follows:

[0136]

[0137] The superscript * indicates the conjugate operation.

[0138] S3.3: Obtain the signal after the echo signal received by the nth receiving element passes through the m-th dimension matched filter.

[0139]

[0140] Where * represents convolution operation.

[0141] because Satisfying the orthogonality condition, the signal after passing through the m-th dimension matched filter can be further expressed as:

[0142]

[0143] S3.4: Obtain the signal y of the target echo received by the nth receiving element after passing through the M-dimensional matched filter. n (t,θ0) is:

[0144]

[0145] S3.5: The signal y after passing the received signals of all N receiving array elements through an M-dimensional matched filter can be represented as an MN×1-dimensional column vector, with the following specific form:

[0146]

[0147] in, Let represent the Kronecker product operation, where b(θ0) is the receive steering vector and a(R0,θ0) is the equivalent transmit steering vector.

[0148]

[0149]

[0150] S4: Based on the expressions for the transmit steering vector and the receive steering vector, obtain the transmit spatial frequency and receive spatial frequency of the real target and the dummy target.

[0151] Step S4 in this embodiment specifically includes:

[0152] S4.1: Based on the expressions for the transmission steering vector and reception steering vector of the real target, obtain the transmission spatial frequency f of the real target. T and the received spatial frequency f R :

[0153]

[0154]

[0155] Where R0 represents the distance between the real target and the radar;

[0156] S4.2: Obtain the corresponding launch spatial frequency of the q-th dummy target. and received space frequency

[0157]

[0158]

[0159] S5: Based on the transmission and reception spatial frequencies, obtain the transmission spatial frequency difference between the real target and the false target.

[0160] As shown in the formula in step S4, the transmission spatial frequency of the target (including real and false targets) is related to both angle and distance, while the reception spatial frequency of the target is angle-dependent. Therefore, targets can be arbitrarily distributed in the transmission-reception two-dimensional spatial frequency domain.

[0161] This step specifically includes:

[0162] S5.1: Considering the existence of distance ambiguity, the true distance of the real target is represented as:

[0163] R0 = r0 + (p-1)R u ,

[0164] Where r0 is the principal value distance of the true target, which is determined by the distance gate size and distance gate number. For the maximum unambiguous distance, f r Indicates PRF (Pulse Repetition Frequency). This is the distance ambiguity number of the real target (i.e., the number of pulses the real target traverses). `int(·)` represents the operation of approximating this number using the tail-removal method. If N... a Let p represent the number of fuzzy intervals, then p∈[1,N] a ].

[0165] S5.2: Obtain the equivalent actual distance of the q-th dummy target.

[0166] For the q-th false target, its equivalent actual distance can be expressed as:

[0167] R q =r q +(p′-1)R u ,

[0168] Where, r q Let be the principal distance of the q-th pseudo-target. Let q be the distance ambiguity number of the q-th false target (i.e., the number of pulses traversed by the q-th false target).

[0169] S5.3: Obtain the true target and the q-th false target using R u The frequency difference in the transmission space is:

[0170]

[0171] in, The non-negative integer part is v, and the positive decimal part is v∈[0,1). It is worth noting that once Δt and f are given... r The values ​​of z and v are known constants. Due to the 2π periodic ambiguity of the exponential term, the influence of the integer term z can be ignored.

[0172] S6: Perform range compensation on the echo signal after matched filtering, and obtain the transmission spatial frequency difference between the real target and the false target after range compensation.

[0173] S6.1: Construct the distance compensation vector.

[0174] Since the principal value distance is available, principal value distance compensation can be performed on the received echo signal. A compensation function is constructed using the principal value distance of the real target as a reference. The distance compensation vector g is further constructed as follows:

[0175]

[0176] Among them, 1 N×1 Represents a column vector of all 1s. This is the emission domain compensation vector.

[0177] S6.2: Using the range compensation vector g to perform range compensation on the echo signal after passing through the M-dimensional matched filter, the expression of the range-compensated received signal is obtained:

[0178]

[0179] Here, ⊙ represents the Hadema product.

[0180] S6.3: Obtain the range-compensated launch spatial frequencies of the real target and the q-th false target:

[0181]

[0182]

[0183] in, The transmission spatial frequency after distance compensation. r is the received spatial frequency after distance compensation. Δ =r q -r0 represents the remaining principal value distance after distance compensation.

[0184] S6.4: For deceptive jamming signals from the main lobe, obtain the spatial frequency difference between the real target and the false target after range compensation:

[0185]

[0186] S7: Design a transmit-receive two-dimensional beamformer based on the transmit spatial frequency difference after distance compensation, and suppress false targets in the echo signal.

[0187] In this step, based on the transmission spatial frequency difference between the real target and the dummy target, a transmit-receive two-dimensional beamformer is designed using the linearly constrained minimum variance (LCMV) criterion. This beamformer then transmits the range-compensated received signal obtained in step S6.2. By using a transmit-receive two-dimensional beamformer, false targets can be suppressed.

[0188] S7.1: In STCA-MIMO radar, the optimization problem is obtained using a linearly constrained minimum variance beamformer:

[0189]

[0190] Where w represents the weight vector, (·) H For the conjugate transpose operation, R j+n The expressions for the interference plus noise covariance matrix, C and F, are as follows:

[0191] C=[u(R0,θ0),u(R0,θ0-Δθ),u(R0,θ0+Δθ)],

[0192] F = [1,1,1] T ,

[0193] Where Δθ represents the angular offset of the real target, and u(R0,θ0) is the virtual steering vector of the real target, which can be expressed as the Kronecker product of the launch steering vector and the receiver steering vector:

[0194]

[0195] S7.2: Obtaining the optimal weight vector using an optimization problem:

[0196]

[0197] S7.3: Use the optimal weight vector to suppress false target signals in the range-compensated received signal to obtain the suppressed signal.

[0198]

[0199] Specifically, the received signal (i.e., the range-compensated received signal) After the designed transmit-receive two-dimensional beamformer is implemented, false targets are suppressed due to range-dimensional mismatch.

[0200] The effectiveness of the method of the present invention will be further illustrated below through simulation experiments.

[0201] I. Simulation Parameters:

[0202] A one-dimensional equidistant linear array is used, horizontally positioned, with element spacing equal to half a wavelength. The number of elements, M = 10, is considered only in this case, focusing on the transmitting array. Each transmitting element emits the same linear frequency modulated signal with a bandwidth of B = 20MHz and a pulse width T. p =20μs, carrier frequency f0 = 1GHz, spacing between transmitting elements d = 0.15m, and number of time-domain sampling points 123. Setting parameters R = 15km and θ = 60°, the time delay Δt' within one pulse width can be obtained. The simulation parameters are shown in Table 1. The parameters of the real and fake targets are shown in Table 2.

[0203] Table 1. System Simulation Parameters

[0204]

[0205] Table 2. True and False Target Parameters

[0206]

[0207] II. Simulation Content:

[0208] (Simulation 1) Under the above simulation parameters, the angle-range slice diagrams of the transmission patterns of traditional phased array radar and STCA-MIMO radar are simulated. The simulation results are as follows: Figure 3 and Figure 4 As shown.

[0209] Depend on Figure 3 and Figure 4 It can be seen that for STCA-MIMO radar, its receive steering vector is only related to the angle, while the transmit steering vector is a two-dimensional function of range R and angle θ. Compared with traditional phased array radar, it has an additional range dimension of freedom. When Δt = 0, the transmit steering vector degenerates into a function that is only related to the angle. At this time, the model degenerates into a traditional phased array radar model.

[0210] (Simulation 2) Under the above simulation parameters, and assuming that real and false targets are distributed at the same distance or angle, the power spectrum diagrams of real and false targets for conventional MIMO radar and STCA-MIMO radar are simulated. The simulation results are as follows: Figure 5 and Figure 6 As shown.

[0211] Depend on Figure 5 and Figure 6 It can be seen that conventional MIMO radar can only distinguish between real targets and false targets 1 at different angles, but cannot distinguish between real targets and false targets 2 at the same angle. In other words, conventional MIMO radar can distinguish between targets in the main lobe and side lobes, but cannot distinguish between targets within the same main lobe. Figure 6 As can be seen, the STCA-MIMO radar can not only distinguish between real and false targets at different angles, but also between real and false targets at the same angle but different distances. In other words, the STCA-MIMO radar can simultaneously distinguish between main lobe targets and side lobe targets, as well as real and false targets within the main lobe. This is because the STCA-MIMO radar introduces additional degrees of freedom, giving it the ability to distinguish between targets at different distances within the main lobe, such as real targets and false targets.

[0212] (Simulation 3) Under the above simulation parameters, the beamformer response of the STCA-MIMO radar designed using the LCMV criterion was simulated. The simulation results are as follows: Figure 7 As shown.

[0213] Depend on Figure 7 It can be seen that the response reaches its maximum value at the location of the real target and forms a notch at the location of the false target, indicating that the STCA-MIMO radar does indeed have the ability to suppress such interference (similar to false target 1 and false target 2).

[0214] (Simulation 4) Under the above simulation parameters, the pulse compression results of conventional MIMO radar and STCA-MIMO radar against real and false targets are simulated. The simulation results are as follows: Figure 8 As shown.

[0215] Depend on Figure 8 It can be seen that conventional MIMO radar can suppress false target 1 but cannot suppress false target 2, while STCA-MIMO radar can suppress both false target 1 and false target 2 simultaneously. This proves the effectiveness of the proposed STCA-MIMO radar main lobe interference suppression method. This simulation verifies the correctness, effectiveness, and reliability of the invention.

[0216] This invention proposes a method for resisting main lobe deception interference in space-time coded array radar. Compared with traditional MIMO radar, it gains additional degrees of freedom in the range dimension and can suppress false targets generated by main lobe deception interference based on the difference in transmission frequency between real and false targets. This invention adopts a novel waveform diversity radar system of space-time coded array, introducing a time delay difference between different array elements. Compared with the frequency stepping design of FDA-MIMO radar, the time delay introduced by the space-time coded array is simpler to implement in engineering. At the same time, at the receiving end, equivalent transmit beamforming can be performed using only a single antenna, increasing the degrees of freedom in the transmission dimension.

[0217] Another embodiment of the present invention provides a storage medium storing a computer program for executing the steps of the method for resisting main lobe deception jamming of space-time coded array radar described in the above embodiments. A further aspect of the present invention provides an electronic device including a memory and a processor. The memory stores a computer program, and the processor, when calling the computer program in the memory, implements the steps of the method for resisting main lobe deception jamming of space-time coded array radar as described in the above embodiments. Specifically, the integrated modules implemented as software functional modules can be stored in a computer-readable storage medium. The software functional modules stored in a storage medium include several instructions to cause an electronic device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0218] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for resisting main lobe deception interference in a space-time coded array radar, characterized in that, include: S1: Transmit orthogonal linear frequency modulated signals using STCA-MIMO radar; S2: Receive echo signals, perform down-conversion processing on the echo signals received by each receiving array element, and obtain the down-converted echo signals of each receiving array element. S3: Perform mixing and matched filtering on the down-converted echo signal of each receiving array element to obtain the matched filtered echo signal, and obtain the transmit steering vector and receive steering vector; S4: Based on the expressions for the transmit steering vector and the receive steering vector, obtain the transmit spatial frequency and receive spatial frequency of the real target and the dummy target; S5: Based on the transmitted spatial frequency and the received spatial frequency, obtain the difference in transmitted spatial frequencies between the real target and the false target; S6: Perform range compensation on the echo signal after matched filtering, and obtain the transmission spatial frequency difference between the real target and the false target after range compensation; S7: Design a transmit-receive two-dimensional beamformer based on the distance-compensated transmit spatial frequency difference, and suppress false targets in the echo signal.

2. The method for resisting main lobe deception interference in a space-time coded array radar according to claim 1, characterized in that, S1 includes: S1.1: Transmit orthogonal linear frequency modulated signals using STCA-MIMO radar, wherein the first... The signal transmitted by each transmitting element after a time delay for ， in, f 0 represents the carrier frequency. This is the time delay between signals transmitted on adjacent transmitting array elements. For the first m Orthogonal encoded signals of each transmitting array element It is a linear frequency modulated signal; S1.2: Under the assumption of narrowband signals, obtain the first... The signal representation when the transmitted signal of each transmitting element reaches the target: ， in, Indicates the first m The time delay of the signal transmitted by each transmitting element This represents the one-way delay of the signal transmitted by the first transmitting element. The spacing between the transmitting elements, At the speed of light, t For time, From the perspective of the goal, This indicates the distance between the radar and the target.

3. The method for resisting main lobe deception interference in a space-time coded array radar according to claim 2, characterized in that, S2 includes: S2.1: Obtain the first n The receiver element receives data from the first receiving element. The echo signal of each transmitting element; S2.2: From The echo signals of the transmitting array elements are superimposed to obtain the first... The echo signals received by each receiving element from all M transmitting elements are: ， in, For wavelength, The frequency modulation slope of the linear frequency modulated signal. Indicates the first m The signal transmitted by each transmitting element; S2.3: Perform down-conversion processing on the echo signals from all M transmitting array elements to obtain the down-converted echo signals: ， in, For complex envelope.

4. The method for resisting main lobe deception interference in a space-time coded array radar according to claim 3, characterized in that, S3 includes: S3.1: Perform a time delay on the echo signal received by each receiving element. The relevant digital mixing is used to obtain the echo signal after digital mixing: ， S3.2: For the first The designed matched filter for the transmitted signal of each transmitting element is as follows: ， Among them, superscript Indicates conjugate operation; S3.3: Obtain the first The echo signal received by the first receiving element passes through the first... m Signal after 3D matched filter : ； S3.4: Obtain the first The target echo received by each receiving element passes through Signal after 3D matched filter : ； S3.5: All The received signals of each receiving element pass through The signal after the 3D matched filter is represented as a Dimensional column vector: ， in, This represents the Kronecker product operation. To receive the guide vector, The equivalent launch steering vector: 。 5. The method for resisting main lobe deception interference in a space-time coded array radar according to claim 4, characterized in that, S4 includes: S4.1: Obtain the transmission spatial frequency of the real target based on the expressions for the transmission steering vector and the reception steering vector of the real target. and received spatial frequency : ， ， in, This indicates the distance between the actual target and the radar; S4.2: Obtain the first The launch space frequency of the decoy target and received spatial frequency : ， ， in, Indicates the first The distance between the decoy target and the radar.

6. The method for resisting main lobe deception interference in a space-time coded array radar according to claim 5, characterized in that, S5 includes: S5.1: When distance ambiguity exists, the true distance of the real target is represented as: ， in, The principal distance to the true target. For the maximum unambiguous distance, The pulse repetition frequency, The distance ambiguity number to the real target. This indicates the operation of rounding down numbers to find their approximate values. S5.2: Obtain the first The equivalent actual distance to each dummy target: ， in, For the first Principal distance of each spurious target For the first The distance blur number of each false target; S5.3: Obtain the true objective and the first A false target The spatial frequency difference of the transmission interval: ， in, The non-negative integer part This is the positive decimal part.

7. The method for resisting main lobe deception interference in a space-time coded array radar according to claim 6, characterized in that, S6 includes: S6.1: Construct a compensation function based on the principal distance of the true target. And construct the distance compensation vector : ， in, Represents a column vector of all 1s. For the emission domain compensation vector; S6.2: Use the distance compensation vector to... The echo signal after the 3D matched filter is then subjected to range compensation to obtain the range-compensated received signal: ， in, Represents the Hadema product; S6.3: Obtain the true objective and the first The transmission spatial frequency of the dummy target after distance compensation: ， ， in, The transmission spatial frequency after distance compensation. This refers to the received spatial frequency after distance compensation. This represents the remaining principal value distance after distance compensation. S6.4: Obtain the spatial frequency difference between the real target and the dummy target after range compensation: 。 8. The method for resisting main lobe deception interference in a space-time coded array radar according to claim 7, characterized in that, S7 includes: S7.1: Obtaining the optimization problem using a linearly constrained minimum variance beamformer: ， in, Represents the weight vector. This is the conjugate transpose operation. The interference plus noise covariance matrix, and The expression is: ， ， in, A virtual guide vector for the real target. , This represents the angular offset of the actual target. S7.2: Obtain the optimal weight vector using the aforementioned optimization problem: ， S7.3: Use the optimal weight vector to suppress the false target signal in the range-compensated received signal to obtain the suppressed signal.

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