A nonlinear time delay-based STCA-MIMO radar anti-jamming method

Abstract

The application discloses a STCA-MIMO radar anti-interference method based on nonlinear time delay, which comprises the following steps: calculating target echo signals based on nonlinear time delay of transmitting array elements; carrying out digital mixing and matching filtering on the target echo signals to obtain preprocessed signals; determining a first transmitting steering vector and a first receiving steering vector according to the preprocessed signals; calculating a covariance matrix of STCA-MIMO radar system receiving data; calculating an adaptive weight vector by using a robust direct data domain beam forming technology based on the covariance matrix and an actual receiving-transmitting joint steering vector of a target; calculating a first receiving-transmitting joint steering vector of the STCA-MIMO radar system; and carrying out beam forming by using the first receiving-transmitting joint steering vector and the adaptive weight vector. The application can effectively suppress interference signals in the main lobe of the STCA-MIMO radar, and solves the problem of the decline of interference suppression performance in the prior art when the interference is located near the distance grating lobe of the main lobe of the real target.

Description

Technical Field

[0001] This invention belongs to the field of radar signal processing technology, specifically relating to an STCA-MIMO radar anti-jamming method based on nonlinear time delay. Background Technology

[0002] STCA (Space-time Coding Array), as an emerging waveform diversity radar system, introduces a small time delay between transmitting array elements, thereby gaining additional degrees of freedom at the transmitting end and achieving full airspace coverage. MIMO (Multiple-Input Multiple-Output) antenna systems in radar systems transmit orthogonal signals between transmitting array elements, and then perform matched filtering at the receiving end to separate the transmitted signals. Compared with traditional phased array radars, MIMO radars offer higher degrees of freedom, stronger anti-jamming performance, and better anti-interception performance. Therefore, combining MIMO radar systems with space-time coding arrays has excellent application prospects. Since the transmission frequency of STCA-MIMO radar has a two-dimensional dependence on range and angle, deceptive interference can be suppressed through adaptive beamforming algorithms.

[0003] However, the existing STCA-MIMO radar system uses a linearly increasing time delay between transmitting array elements, and its non-adaptive beam pattern will have periodic grating lobes in the range dimension. When the interference in the main lobe is located near the periodic grating lobe of the real target, the adaptive beamforming algorithm will suppress the real target signal while suppressing the interference, resulting in a decrease in interference suppression performance. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides an STCA-MIMO radar anti-jamming method based on nonlinear time delay. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] This invention provides an anti-jamming method for STCA-MIMO radar based on nonlinear time delay, applied to STCA-MIMO radar systems, comprising:

[0006] Calculate the target echo signal under the STCA-MIMO radar system based on the nonlinear time delay of the transmitted array elements;

[0007] The target echo signal is digitally mixed and matched filtered to obtain a preprocessed signal;

[0008] The first transmit steering vector and the first receive steering vector of the STCA-MIMO radar system are determined based on the preprocessed signal.

[0009] Calculate the covariance matrix of the received data from the STCA-MIMO radar system;

[0010] Based on the covariance matrix and the target's actual receive-transmit joint steering vector, an adaptive weight vector is calculated using robust direct data domain beamforming technology.

[0011] Calculate the first transmit-receive joint steering vector based on the first transmit steering vector and the first receive steering vector of the STCA-MIMO radar system;

[0012] Beamforming is performed using the first receive-transmit joint steering vector and the adaptive weighting vector.

[0013] In one embodiment of the present invention, the target echo signal under the STCA-MIMO radar system is calculated according to the following formula:

[0014]

[0015] In the formula, t represents time, θ represents the target angle, f0 represents the signal carrier frequency, and s n Let represent the transmitted signal of the nth transmitting element, R represent the distance to the target, λ represent the wavelength of the transmitted signal, c represent the speed of light in vacuum, and Δt represent the transmitted signal. n Let represent the nonlinear time delay of the nth transmitting element, μ represent the frequency modulation coefficient of the transmitted signal, d represent the spacing between the transmitting elements and the receiving elements, and y represent the nonlinear time delay of the nth transmitting element. m (t,θ) represents the target echo signal received by the m-th receiving element in the STCA-MIMO radar system, where n = 1, 2, ..., N, m = 1, 2, ..., M, and N and M represent the number of transmitting and receiving elements, respectively. The transmitted signals of each transmitting element are orthogonal to each other.

[0016] In one embodiment of the present invention, the nonlinear delay of the transmitting array element includes logarithmic delay, square delay, and sinc delay.

[0017] In one embodiment of the present invention, the step of performing digital mixing and matched filtering on the target echo signal to obtain a preprocessed signal includes:

[0018] The target echo signal received by the m-th receiving element is digitally mixed according to the following formula:

[0019]

[0020] In the formula, The target echo signal after digital mixing;

[0021] The target echo signal after digital mixing is subjected to matched filtering to obtain the preprocessed signal transmitted by the nth transmitting element and received by the mth receiving element:

[0022]

[0023] In the formula, ξ represents the complex amplitude of the preprocessed signal.

[0024] In one embodiment of the present invention, the step of determining the transmit steering vector and receive steering vector of the STCA-MIMO radar system based on the preprocessed signal includes:

[0025] Arrange the preprocessed signals received by the M receiving array elements to obtain the preprocessed signal y at the receiving end:

[0026]

[0027] Wherein, the preprocessed signal y at the receiving end satisfies the following with the transmit steering vector a(R,θ) and receive steering vector b(θ) of the STCA-MIMO radar system: Indicates the Kronecker product;

[0028] Based on the preprocessed signal y from the receiving end, the transmit steering vector a(R,θ) and receive steering vector b(θ) of the STCA-MIMO radar system are calculated according to the following formulas:

[0029]

[0030]

[0031] In one embodiment of the present invention, the covariance matrix R of the STCA-MIMO radar system received data is calculated according to the following formula. x :

[0032]

[0033] In the formula, K represents the number of sampling snapshots, and y k This represents the k-th snapshot data obtained by sampling the received data, (·) H This indicates the conjugate transpose.

[0034] In one embodiment of the present invention, the adaptive weight vector is calculated according to the following formula:

[0035]

[0036] In the formula, st represents the constraint condition, v represents the target's actual receive-transmit joint steering vector, R0 represents the target's actual distance, θ0 represents the target's actual angle, and σ represents the uncertain set of the target's actual receive-transmit joint steering vector v.

[0037] In one embodiment of the present invention, the first receive-transmit joint steering vector u(R,θ) is calculated according to the following formula:

[0038]

[0039] In the formula, u(R,θ) represents the first receive-transmit joint steering vector of the STCA-MIMO radar system at position (R,θ), a(R,θ) represents the transmit steering vector of the STCA-MIMO radar system at position (R,θ), and b(θ) represents the receive steering vector of the STCA-MIMO radar system at angle θ. This represents the Kronecker product operation.

[0040] In one embodiment of the present invention, beamforming is performed using the first receive-transmit joint steering vector and the adaptive weighting vector according to the following formula:

[0041] P(R,θ)=|w H u(R,θ)|

[0042] In the formula, |·| represents the modulus operation, and P(R,θ) represents the signal level of the STCA-MIMO radar system at position (R,θ) after beamforming.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] This invention provides an anti-jamming method for STCA-MIMO radar based on nonlinear time delay, which can effectively suppress interference signals in the main lobe of STCA-MIMO radar, and at the same time solves the problem of decreased interference suppression performance in the prior art when the interference is located near the range grating lobe of the real target's main lobe.

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0046] Figure 1 This is a flowchart of an STCA-MIMO radar anti-jamming method based on nonlinear time delay provided in an embodiment of the present invention;

[0047] Figure 2a This is an adaptive beam pattern under linear time delay provided in an embodiment of the present invention;

[0048] Figure 2b This is an adaptive beam pattern under linear time delay provided in an embodiment of the present invention;

[0049] Figure 2c This is the adaptive beam pattern under squared time delay provided in the embodiments of the present invention;

[0050] Figure 2d This is the adaptive beam pattern under sinc delay provided in the embodiments of the present invention;

[0051] Figure 3a This is a schematic diagram of the influence curves of the distance between the interfering target and the grating lobe on the interference performance under different time delays provided by the embodiments of the present invention;

[0052] Figure 3b This is a schematic diagram showing the effect of the signal-to-noise ratio of the true target input on interference suppression performance under different time delays, as provided in the embodiments of the present invention. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0054] In existing STCA-MIMO radar adaptive beamforming anti-jamming methods, the time delay between transmitting array elements is linearly increased, which causes periodic grating lobes to appear in the range dimension of the STCA-MIMO radar's transmit pattern. When the interference in the main lobe is located near the periodic grating lobe of the real target, the adaptive beamforming algorithm will suppress the real target signal while suppressing the interference, thus causing a decrease in interference suppression performance.

[0055] To address the aforementioned problems, this invention provides an STCA-MIMO radar anti-jamming method based on nonlinear time delay.

[0056] Figure 1 This is a flowchart of an STCA-MIMO radar anti-jamming method based on nonlinear time delay provided in an embodiment of the present invention. Figure 1 As shown, this embodiment of the invention provides an STCA-MIMO radar anti-jamming method based on nonlinear time delay, applied to an STCA-MIMO radar system, including:

[0057] S1. Calculate the target echo signal under the STCA-MIMO radar system based on the nonlinear time delay of the transmitting array elements;

[0058] S2. Perform digital mixing and matched filtering on the target echo signal to obtain the preprocessed signal;

[0059] S3. Determine the first transmit steering vector and the first receive steering vector of the STCA-MIMO radar system based on the preprocessed signal;

[0060] S4. Calculate the covariance matrix of the received data from the STCA-MIMO radar system;

[0061] S5. Based on the covariance matrix and the target's actual receive-transmit joint steering vector, an adaptive weight vector is calculated using robust direct data domain beamforming technology.

[0062] S6. Calculate the first transmit-receive joint steering vector based on the first transmit steering vector and the first receive steering vector of the STCA-MIMO radar system;

[0063] S7. Beamforming is performed using the first receiver-transmitter joint steering vector and the adaptive weighting vector.

[0064] Specifically, this invention uses an N-transmitter, M-receiver co-located monostatic STCA-MIMO radar system, where the transmitting array comprises N transmitting elements and the receiving array comprises M receiving elements. Both the transmitting and receiving arrays are uniformly spaced linear arrays with an element spacing of half a wavelength. Furthermore, the transmitted signal of each transmitting element is a linear frequency modulated signal. Therefore, the transmitted signal of the nth transmitting element at the transmitting end can be expressed as:

[0065]

[0066] Among them, l n Let g(t) represent the coding coefficient of the nth transmitting element, and g(t) = exp(jπμt). 2 ) represents a linear frequency modulated signal, and μ represents the frequency modulation coefficient. Optionally, the transmitted signals of each transmitting element in the STCA-MIMO radar system are mutually orthogonal, therefore:

[0067]

[0068] For example, the nonlinear delay of the transmitting array element may include logarithmic delay, square delay, and sinc delay, and the logarithmic delay, square delay, and sinc delay of the nth transmitting array element are respectively expressed as:

[0069] Δt n =ln(n)Δt(3)

[0070]

[0071]

[0072] Where Δt is a preset reference delay, typically taken as... B represents the bandwidth of the transmitted signal.

[0073] In this embodiment, the target echo signal under the STCA-MIMO radar system is calculated according to the following formula:

[0074]

[0075] In the formula, t represents time, θ represents the target angle, f0 represents the signal carrier frequency, and s n Let represent the transmitted signal of the nth transmitting element, R represent the distance to the target, λ represent the wavelength of the transmitted signal, c represent the speed of light in vacuum, and Δt represent the transmitted signal. n Let represent the nonlinear time delay of the nth transmitting element, μ represent the frequency modulation coefficient of the transmitted signal, d represent the spacing between the transmitting elements and the receiving elements, and y represent the nonlinear time delay of the nth transmitting element. m (t,θ) represents the target echo signal received by the m-th receiving element in the STCA-MIMO radar system, where n = 1, 2, ..., N, m = 1, 2, ..., M, and N and M represent the number of transmitting and receiving elements, respectively. The transmitted signals of each transmitting element are orthogonal to each other.

[0076] In the STCA-MIMO radar system, the transmitted signals of the transmitting elements are superimposed in space after carrier frequency modulation as follows:

[0077]

[0078] Considering Δt n The quadratic term is usually taken to be very small, so the quadratic term in equation (6) above is generally ignored, and can be transformed into:

[0079]

[0080] Assuming a target (R,θ) in space under far-field conditions, the resultant signal of the transmitted signal at the target can be obtained from formula (7):

[0081]

[0082] The transmitted signal, after being reflected by the target, returns to the m-th receiving element at the receiver. Its signal form can be expressed as:

[0083]

[0084] In step S2 above, the step of performing digital mixing and matched filtering on the target echo signal to obtain the preprocessed signal includes:

[0085] S201. Perform digital mixing on the target echo signal received by the m-th receiving element according to the following formula:

[0086]

[0087] In the formula, The target echo signal after digital mixing;

[0088] S202. Perform matched filtering on the target echo signal after digital mixing to obtain the preprocessed signal transmitted by the nth transmitting element and received by the mth receiving element:

[0089]

[0090] In the formula, ξ represents the complex amplitude of the preprocessed signal.

[0091] Specifically, the target echo signal of the m-th receiving array element is digitally mixed to remove the carrier frequency term, resulting in the mixed target echo signal as follows:

[0092]

[0093] Furthermore, in order to separate the transmitted signal at the receiving end, the mixed target echo signal is further subjected to a time delay Δt-related mixing operation and N-dimensional matched filtering, where the nth mixing coefficient and the matched filter are exp(2πμ(n-1)tΔt) and , respectively. The final preprocessed signal obtained by the nth transmitting element and the mth receiving element is as follows:

[0094]

[0095] Where ξ represents the complex amplitude of the preprocessed signal. Since the transmitted signals of each array element in this embodiment are orthogonal to each other under the MIMO system, the second term in equation (11) is 0, resulting in the final expression for the preprocessed signal:

[0096]

[0097] In step S3 above, the step of determining the first transmit steering vector and the first receive steering vector of the STCA-MIMO radar system based on the preprocessed signal includes:

[0098] S301. Arrange the preprocessed signals received by the M receiving array elements to obtain the preprocessed signal y at the receiving end:

[0099]

[0100] The preprocessed signal y at the receiver satisfies the following conditions with the transmit steering vector a(R,θ) and receive steering vector b(θ) of the STCA-MIMO radar system: Indicates the Kronecker product;

[0101] S302. Based on the preprocessed signal y from the receiver, calculate the transmit steering vector a(R,θ) and receive steering vector b(θ) of the STCA-MIMO radar system according to the following formula:

[0102]

[0103]

[0104] In this embodiment, the total target echo signal obtained by arranging the signals from the M receiving channels is represented as follows:

[0105]

[0106] Where ξ represents the complex amplitude of the preprocessed signal, Let represent the Kronecker product, ⊙ represent the Huffman product, b(θ) be the receive steering vector of the STCA-MIMO radar system, and a(R,θ) be the transmit steering vector of the STCA-MIMO radar system. These can be expressed as follows:

[0107]

[0108]

[0109] For different nonlinear time delays, the transmit steering vector of the STCA-MIMO radar system is different, for example:

[0110] For logarithmic time delay, the transmit steering vector of the STCA-MIMO radar system is expressed as:

[0111]

[0112] For the square time delay, the transmit steering vector of the STCA-MIMO radar system is expressed as:

[0113]

[0114] For the sinc time delay, the transmit steering vector of the STCA-MIMO radar system is expressed as:

[0115]

[0116] In step S6 above, the covariance matrix R of the STCA-MIMO radar system received data is calculated according to the following formula. x :

[0117]

[0118] In the formula, K represents the number of sampling snapshots, and y k This represents the k-th snapshot data obtained by sampling the received data, (·). H This indicates the conjugate transpose.

[0119] According to formula (18), the STCA-MIMO radar system has two degrees of freedom in range and angle at the transmitter. Therefore, it can detect and identify targets or interference through two-dimensional matched filtering. However, since the range information of deceptive interference is modulated by the jammer, the mathematical statistical characteristics of the interference signal in different range resolution units generally do not satisfy the IID condition. Therefore, its covariance matrix cannot be calculated through adjacent range loops. For fast-sampling data with different pulse counts, since the false target must satisfy the IID condition in slow time, the covariance can be estimated using fast-sampling data with different pulse counts. The target data covariance is:

[0120]

[0121] Optionally, this embodiment utilizes robust direct data domain beamforming technology to calculate adaptive weight vectors.

[0122] The robust beamforming expression is as follows:

[0123]

[0124] In the formula, st represents the constraint condition, v represents the target's actual receive-transmit joint steering vector, R0 represents the target's actual distance, θ0 represents the target's actual angle, and σ represents the uncertain set of the target's actual receive-transmit joint steering vector v, satisfying ||σ||≤ε.

[0125] In step S6 above, the first receiver-transmitter joint steering vector u(R,θ) is calculated according to the following formula:

[0126]

[0127] In the formula, u(R,θ) represents the first receive-transmit joint steering vector of the STCA-MIMO radar system at position (R,θ), a(R,θ) represents the transmit steering vector of the STCA-MIMO radar system at position (R,θ), and b(θ) represents the receive steering vector of the STCA-MIMO radar system at angle θ. This represents the Kronecker product operation.

[0128] Specifically, after calculating the first receiver-transmitter joint steering vector at any location of the STCA-MIMO radar in space and time, the adaptive weight vector w obtained by solving according to formula (21) is used for beamforming to suppress the interference target.

[0129] Finally, combining formulas (20) and (21), the signal level at position (R, θ) in the STCA-MIMO radar beam pattern after adaptive beamforming can be expressed as:

[0130] P(R,θ)=|w H u(R,θ)|

[0131] In the formula, |·| represents the modulus operation, and P(R,θ) represents the signal level of the STCA-MIMO radar system at position (R,θ) after beamforming.

[0132] The following simulation experiment further illustrates the STCA-MIMO radar anti-jamming method based on nonlinear time delay.

[0133] Specifically, the simulation uses a co-located uniformly spaced linear array with the same number of transmitting and receiving elements. The range dimension period of the STCA-MIMO radar system under linear time delay is 30 km. Other simulation parameters are shown in Table 1 below.

[0134] Table 1

[0135]

[0136]

[0137] Figure 2a This is an adaptive beam pattern under linear time delay provided in an embodiment of the present invention. Figure 2b This is an adaptive beam pattern under linear time delay provided in an embodiment of the present invention. Figure 2c This is the adaptive beam pattern under squared time delay provided in an embodiment of the present invention. Figure 2d This is an adaptive beam pattern under sinc delay provided in an embodiment of the present invention. For example... Figures 2b-2d As shown, simulations of adaptive beam patterns under different time delays demonstrate that for STCA-MIMO radar systems employing different nonlinear time delays, the adaptive beamforming method can suppress interfering targets near the grating lobe of the main lobe of the target. Figure 2a As shown, although the STCA radar with linear time delay can also suppress the interference target signal, it will also suppress the target signal at the main lobe, thereby reducing the radar's interference suppression performance.

[0138] Figure 3a This is a schematic diagram illustrating the impact of the distance between the interfering target and the grating lobe on the interference performance under different time delays, as provided in an embodiment of the present invention. Figure 3b This is a schematic diagram showing the effect of the signal-to-noise ratio of the true target input on interference suppression performance under different time delays, as provided in the embodiments of the present invention. Figure 3aWith a fixed target signal signal-to-noise ratio of 5dB, when using linear time delay, the output signal-to-noise ratio increases as the interfering target moves further away from the grating lobe of the main lobe. This indicates that when using linear time shift, if the interfering target is close to the grating lobe of the main lobe, the adaptive interference suppression method will also suppress the target, leading to a decrease in interference suppression performance. However, with the STCA-MIMO radar using nonlinear time delay, the range periodicity of the array beam pattern is disrupted, so the adaptive anti-interference method can effectively suppress the interfering signal regardless of where the interfering target is located within the radar's effective range within the main lobe. Figure 3b The fixed dummy target is located 100m from the main lobe grating lobe. Comparing the output signal-to-noise ratio with the same input signal-to-noise ratio, it can be seen that STCA-MIMO has better anti-interference performance when using nonlinear time delay.

[0139] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0140] The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples" indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0141] Although this application has been described herein in conjunction with various embodiments, other variations of the disclosed embodiments can be understood and implemented by those skilled in the art in carrying out the claimed application by reviewing the accompanying drawings, the disclosure, and the appended claims.

[0142] 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 anti-jamming radar based on nonlinear time delay, characterized in that, Applications in STCA-MIMO radar systems include: Calculate the target echo signal under the STCA-MIMO radar system based on the nonlinear time delay of the transmitted array elements; The target echo signal is digitally mixed and matched filtered to obtain a preprocessed signal; The steps of determining the first transmit steering vector and the first receive steering vector of the STCA-MIMO radar system based on the preprocessed signal include: Will The preprocessed signals received by each receiving array element are arranged to obtain the preprocessed signal at the receiving end. for: in, Indicates by the first The launch element is launched, the first... The preprocessed signal received by each receiving array element, the preprocessed signal at the receiving end. With the transmit steering vector of the STCA-MIMO radar system and receiving guide vector satisfy: , Indicates the Kronecker product; According to the preprocessed signal of the receiving end The transmit steering vector of the STCA-MIMO radar system is calculated according to the following formula. and receiving guide vector : ； In the formula, Indicates the wavelength of the transmitted signal. Represents the speed of light in a vacuum. The frequency modulation coefficient represents the frequency of the transmitted signal. This indicates the spacing between the transmitting elements and the receiving elements. Indicates the first The nonlinear time delay of each transmitting element, From the perspective of the target, , , , These represent the number of transmitting array elements and receiving array elements, respectively, and the transmitted signals of each transmitting array element are mutually orthogonal; Calculate the covariance matrix of the received data from the STCA-MIMO radar system; Based on the covariance matrix and the target's actual receive-transmit joint steering vector, an adaptive weight vector is calculated using robust direct data domain beamforming technology; the adaptive weight vector is calculated according to the following formula: In the formula, Indicates constraints. This represents the target's actual receive-transmit joint steering vector. Indicates the actual distance to the target. This represents the actual angle from which the target is viewed. This represents the target's actual receive-transmit joint steering vector. An uncertain set, in which, ; This represents the covariance matrix of the received data from the STCA-MIMO radar system. Represents the adaptive weight vector; Based on the first transmit steering vector and the first receive steering vector of the STCA-MIMO radar system, calculate the first receive-transmit joint steering vector; calculate the first receive-transmit joint steering vector according to the following formula. : ； In the formula, This indicates the location of the STCA-MIMO radar system. The first receiver-transmitter joint steering vector at the location, This indicates the location of the STCA-MIMO radar system. The launch steering vector at that location, This indicates that the STCA-MIMO radar system is at an angle The receiving guide vector at the location, This represents the Kronecker product operation; Beamforming is performed using the first receive-transmit joint steering vector and the adaptive weighting vector; beamforming is then performed using the first receive-transmit joint steering vector and the adaptive weighting vector according to the following formula: In the formula, This represents the modulo operation. This indicates the location of the STCA-MIMO radar system after beamforming. The signal level at that location.

2. The STCA-MIMO radar anti-jamming method based on nonlinear time delay according to claim 1, characterized in that, The target echo signal under the STCA-MIMO radar system is calculated using the following formula: In the formula, Indicates time, Indicates the signal carrier frequency. Indicates the first The transmitted signal of each transmitting element Indicates the distance to the target. Indicates the first The nonlinear time delay of each transmitting element, For the first STCA-MIMO radar system The target echo signal received by each receiving array element.

3. The STCA-MIMO radar anti-jamming method based on nonlinear time delay according to claim 2, characterized in that, The nonlinear time delay of the transmitting array element includes logarithmic time delay, square time delay, and sinc time delay.

4. The STCA-MIMO radar anti-jamming method based on nonlinear time delay according to claim 2, characterized in that, The steps of performing digital mixing and matched filtering on the target echo signal to obtain a preprocessed signal include: The first is calculated according to the following formula. The target echo signal received by each receiving array element is digitally mixed: In the formula, The target echo signal after digital mixing; The target echo signal after digital mixing is subjected to matched filtering to obtain the signal obtained by the first... The launch element is launched, the first... The preprocessed signal received by each receiving array element is: In the formula, This represents the complex amplitude of the preprocessed signal.

5. The STCA-MIMO radar anti-jamming method based on nonlinear time delay according to claim 1, characterized in that, Calculate the covariance matrix of the received data from the STCA-MIMO radar system using the following formula. : In the formula, Indicates the number of snapshots. This indicates the first sample obtained from the received data. A snapshot data, This indicates the conjugate transpose.

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