A radar pulse coding based repeater range deception jamming suppression method

Abstract

The application provides a radar pulse coding-based repeater range deception jamming suppression method, comprising the following steps: constructing a single-base one-dimensional linear array MIMO radar system; performing signal coding weighting between different array elements and different transmission coherent processing pulses; the coded signal contains a coding phase term coefficient related to target distance and pulse number parameters; the weighted signal is conjugate decoded at a receiving end; by using pre-configured decoding parameters, echo signals containing different steering vectors corresponding to different angles, different distances and different coherent pulse sequences can be obtained during decoding; high-dimensional signal processing is performed on the signals with different steering vectors after decoding; and different target or jamming signal echoes can be distinguished according to the different steering vectors. The method provided by the application can distinguish and separate real target echoes submerged in strong range deception jamming signals.

Description

Technical Field

[0001] This invention relates to the field of pulse radar technology, and in particular to a radar transponder-based range deception jamming suppression method based on pulse coding. Background Technology

[0002] During the radar search phase, the jammer receives and stores the modulated and forwarded radar signal. By using time delays across pulse cycles, it generates false signals with different range gates. Although there are target echoes during the initial search phase, the radar system's tracking function fails when the jammer begins forwarding high-power deception jamming.

[0003] For range deception jamming signals and target signals entering the radar transmitter at the same angle, current conventional anti-jamming technologies are difficult to suppress. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to distinguish between range deception jamming signals and target signals entering the radar transmitter from the same angle. In view of this, this invention provides a radar-based pulse coding-based repeater-type range deception jamming suppression method.

[0005] The technical solution adopted in this invention is a method for knowledge extraction from unstructured text data based on a large language model, comprising:

[0006] Step S1: Construct a monostatic one-dimensional linear array MIMO radar. The transmitting array is a uniform linear array with N elements, and the receiving array is a uniform linear array with M elements. The element spacing between the center point of the transmitting array and the center point of the receiving array is d. Within the detection range of the MIMO radar, there are real targets and false targets, and the false targets are range deception interference.

[0007] Step S2: Determine the phase-coded transmission signal of each element in the transmission array. The weighted encoding of the transmission signal includes the minimum unambiguous radar range and coherent pulse sequence parameters. The transmission signals of any two elements in the transmission array are orthogonal to each other.

[0008] Step S3: Obtain the received signal of each element in the receiving array; perform matched filtering and conjugate decoding on the received signal of each element in the receiving array to obtain the echo signal of the target with different angles, different distances and different coherent pulse sequence steering vectors within the detection range of the MIMO radar;

[0009] Step S4: Perform high-dimensional signal processing on the echo signals of different steering vectors after decoding, where different steering vectors represent different target or interference signal echoes;

[0010] Step S5: Based on the distance or angle information of the signal, the target signal and the interference signal are preserved and suppressed respectively.

[0011] In one embodiment, the radar adopts a monostatic MIMO one-dimensional linear array system, with M-dimensional transmitting elements and N-dimensional receiving elements, and the element spacing d is set to half a wavelength.

[0012] Compared with the prior art, the present invention has at least the following advantages:

[0013] The radar pulse code-based repeater-type range deception jamming suppression method provided by this invention can distinguish and separate real target echoes that are submerged in strong range deception jamming signals. Attached Figure Description

[0014] Figure 1 This is a flowchart of a radar transponder-based range deception jamming suppression method based on pulse coding according to an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of an array structure according to an embodiment of the present invention;

[0016] Figure 3 This is a schematic diagram of pulse phase encoding according to an embodiment of the present invention;

[0017] Figure 4 This is a schematic diagram of the signal separation simulation results of pulse coding according to an embodiment of the present invention;

[0018] Figure 5 This is a schematic diagram illustrating the simulation results of pulse coding separation and comparison according to an embodiment of the present invention. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0020] In the accompanying drawings, the thickness, size, and shape of the objects have been slightly exaggerated for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale.

[0021] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed feature, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0022] As used herein, the terms “basically,” “approximately,” and similar terms are used as terms of approximation rather than terms of degree, and are intended to describe inherent biases in measured or calculated values ​​that will be recognized by those skilled in the art.

[0023] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] The steps described in the specification and the flowcharts in the accompanying drawings of this invention are not necessarily to be strictly followed according to the step numbers; the execution order of the steps can be changed. Furthermore, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be broken down into multiple steps.

[0026] In the first embodiment of the present invention, a radar transponder-based range spoofing jamming suppression method based on pulse coding is provided, such as... Figure 1 As shown, the specific steps include the following:

[0027] Step S1: Construct a monostatic one-dimensional linear array MIMO radar. The transmitting array is a uniform linear array with N elements, and the receiving array is a uniform linear array with M elements. The element spacing between the center point of the transmitting array and the center point of the receiving array is d. Within the detection range of the MIMO radar, there are real targets and false targets, and the false targets are range deception interference.

[0028] Step S2: Determine the phase-coded transmission signal of each element in the transmission array. The weighted encoding of the transmission signal includes the minimum unambiguous radar range and coherent pulse sequence parameters. The transmission signals of any two elements in the transmission array are orthogonal to each other.

[0029] Step S3: Obtain the received signal of each element in the receiving array; perform matched filtering and conjugate decoding on the received signal of each element in the receiving array to obtain the echo signal of the target with different angles, different distances and different coherent pulse sequence steering vectors within the detection range of the MIMO radar;

[0030] Step S4: Perform high-dimensional signal processing on the echo signals of different steering vectors after decoding, where different steering vectors represent different target or interference signal echoes;

[0031] Step S5: Based on the distance or angle information of the signal, the target signal and the interference signal are preserved and suppressed respectively.

[0032] The method provided by the present invention will be described in detail below.

[0033] refer to Figure 2 The radar employs a monostatic MIMO one-dimensional linear array system, with M-dimensional transmitting elements and N-dimensional receiving elements. The element spacing d is set to half a wavelength, and the number of coherent pulses processed is K. The angle θ between the desired far-field target and the array element is shown in the figure above. The signal transmitted from the m-th element can be expressed as:

[0034]

[0035] Where rect[] is the rectangular window function, which represents the window shape function of the pulse signal, T p The pulse width is represented by ε, and the orthogonal waveform corresponding to the m-th channel is represented by ε. m (t), in the ideal case, the orthogonality condition is expressed as follows:

[0036]

[0037] The pulse codes are constructed below based on different pulse numbers. The phase of the pulse code loaded by the k-th pulse of the m-th element is represented as:

[0038] ρ mk =exp[-j2πξ(m-1)(k-1)]. (3)

[0039] Where ξ represents the pulse coding coefficient, here we assume the pulse coding coefficient ξ = ΔfR u / c, Δf << f0, the frequency increment of the coefficient is much smaller than f0, R u R represents the maximum unambiguous range corresponding to the radar pulse period T.u =Tc / 2, where c represents the speed of light. Encoding is applied to each signal pulse in each array element through phase weighting, the process being as follows: Figure 3 As shown.

[0040] After the signal is reflected by the far-field target, orthogonally matched filtered, and down-converted, the k-th pulse signal transmitted by the m-th array element and received by the n-th array element is represented as:

[0041]

[0042] Where μ is the product of the target scattering coefficient and the signal propagation coefficient during signal propagation, ρ mk Let (m-1)dcosθ / c and (n-1)dcosθ / c be the pulse codes for the m-th transmitting element and the k-th pulse, respectively, and let (m-1)dcosθ / c be the phase difference between the corresponding transmitting and receiving elements and the reference element.

[0043] The corresponding signals above are decoded using the conjugate of the same coding coefficients. Therefore, the coding coefficients ρ in equation (4) are... mk The corresponding decoding coefficients are expressed as follows: The received signal is decoded by phase weighting, and the decoded signal is... As shown in the following formula:

[0044]

[0045] The following details the situation where distance spoofing relay interference signals exist across pulse cycles.

[0046] Since the principle of range-deception relay jamming is that the jammer receives pulses and delays their transmission, the pulse sequence number of the jamming signal will lag behind the pulse sequence number of the target echo after the delay. Without loss of generality, we will discuss range-deception relay jamming with a delay spanning one pulse cycle as an example, assuming the delay modulation time is T. τ When the target echo pulse number is k, the jammer forwards the target echo signal pulse number with a one-pulse-period delay across the domain as k-1. Therefore, the jamming signal received from the m-th array element, the n-th array element, and the (k-1)-th pulse can be expressed as:

[0047]

[0048] Where μ j The product of the target scattering coefficient and the signal propagation coefficient of the jammer's forwarded signal is shown. Observing that the above formula is the same as the form of formula (4), except that the target signal (k-1) is 1 greater than the jamming signal (k-2) in the phase coefficient of the pulse code.

[0049] For the m-th array element transmitting, the n-th array element receiving, and the k-th pulse signal, the signal y received by the receiver after the interference signal and the target reflected echo are superimposed is expressed as:

[0050] y = x j +x. (7)

[0051] Since the receiver cannot distinguish between the superimposed interference and the target signal, a unified decoding operation is performed on both types of signals. The decoding phase-weighted process is as follows:

[0052]

[0053] Observing the above formula, it can be seen that after decoding, apart from the signal gain, the distance spoofing signal has an additional encoded phase term Δρ=j2πΔfR compared to the echo signal. u / c(m-1), the remaining transmit and receive angular frequencies and Doppler frequencies are the same for the target signal and the interference signal. Since the coefficient Δρ(m-1) is consistent with the coefficient of the transmit spatial angular frequency f0(m-1)dcosθ / c, they are combined when representing the spatial angular frequency below.

[0054] The following formula is used to determine the spatial angular frequency f of the decoded target echo transmission and reception. T f R They are represented as follows:

[0055]

[0056] The frequency components corresponding to the interference signal are represented as follows:

[0057]

[0058] Because the space angular frequency f of the two types of signals emitted after decoding is... T Therefore, the two signals can be separated based on this characteristic. Separating the superimposed signal received at each fast time, there are K coherent cumulative pulses, so a total of K separations are performed. The transmitted pulse signal vectors received by all M transmitting array elements and all N receiving array elements can be represented as:

[0059] Y MN =X MNj +X MN (11)

[0060] in All are MN×G dimensional column vectors, where G represents the total number of time-domain sampled signal samples. The corresponding decoded received signal is...

[0061] The following is the received and decoded data. The signals are separated. Both the interference signal and the target signal are non-Gaussian signals, while only the noise component in the received echo is a Gaussian signal. Furthermore, the number of separated signals is less than the number of array elements. These conditions satisfy the algorithm requirements, therefore, separation can be performed.

[0062] First, a preprocessing matrix W is constructed. After the received signal is multiplied by the preprocessing matrix, the spectral spaces corresponding to the signal eigenvalues ​​have better orthogonality. Both the interference signal and the target signal are non-Gaussian signals, while only the noise term in the received echo is a Gaussian signal. The process is as follows.

[0063] The covariance matrix corresponding to the signal Where G represents The total number of samples in the time domain is used to perform eigenvalue decomposition on R to obtain R = UΛU H The preprocessing matrix W is obtained as follows:

[0064] W=(Λ-δ 2 I)U T (12)

[0065] Where, δ 2 Indicates noise The power is given by Λ, where Λ is the diagonal matrix of eigenvalues, and U is the matrix formed by the corresponding eigenvectors. The preprocessed received signal p can be expressed as:

[0066]

[0067] After preprocessing, the following higher-order matrix corresponding to the signal vector p is obtained. The process of obtaining the matrix can be expressed as follows:

[0068]

[0069]

[0070] The expression for cum is defined as follows:

[0071]

[0072] For D p Singular value decomposition has

[0073]

[0074] The matrix U obtained from the above formula d It can be used to separate mixed signals. The final matrix composed of the separated interference and signal can be represented as:

[0075]

[0076] The resulting matrix Y, formed by separating the interference and target signals, is used to perform pulse compression on the signals in each row of the matrix using the original LFM waveform, yielding fast time-range information. Due to the characteristics of the separation algorithm, it is impossible to pinpoint the exact row of the matrix where the interference and target signals reside. However, pulse compression can yield target echoes at different distances, which can then be combined with prior radar-detected target information for differentiation.

[0077] Compared with the prior art, this embodiment has at least the following advantages:

[0078] This invention analyzes and proposes a pulse coding-based method for separating and suppressing range spoofing interference signals. This method can distinguish and separate real target echoes that are submerged in strong range spoofing interference signals.

[0079] During the radar search phase, the jammer receives and stores modulated radar signals, generating false signals with different range gates through time delays across pulse cycles. Although target echoes are detected in the initial search phase, the radar system's tracking function fails once the jammer begins relaying high-power deception jamming. This paper proposes a method to distinguish and suppress jamming signals from target signals based on this type of range deception jamming, and verifies its effectiveness through signal modeling, simulation analysis, and method comparison.

[0080] The second embodiment of the present invention is based on the above embodiments and combines... Figure 4 as well as Figure 5 Here is an application example of the present invention.

[0081] The following is an experimental simulation of the above algorithm. The parameters of the radar array elements, transmitted signal, deception signal, and target signal are shown in the table below:

[0082] Table 1 Simulation Parameters

[0083]

[0084] For the separated signal matrix Y, each row of vector data is pulse-compressed using the original LFM waveform. The figure below shows the fast-time echo data before and after pulse compression. It can be seen that after separation, although the echo signals are at the same angle of 0 degrees, due to pulse coding modulation, the signal transmission spatial angular frequency contains a frequency term related to the pulse number k. After decoding the same pulse, this term is canceled out by the coding and decoding. After decoding the pulse signal of the cross-pulse range deception, this term still exists, as can be seen from Equations (9) and (10). Therefore, the target echo and the deception interference signal have different steering vectors. Based on the difference in steering vectors, the target signal and the modulation interference signal of range deception are distinguished, corresponding to different range echoes after pulse compression. The range deception interference signal corresponds to distances of 11km and 14km, respectively, and the target echo signal corresponds to a distance of 12.5km, as follows. Figure 4 As shown, (a), (c), and (e) correspond to the pulse sampling signals of rows 1 to 3 of the Y matrix, respectively, and (b), (d), and (f) are the signal diagrams after pulse compression. It can be seen that although the three signal echoes cannot pinpoint the target or interference signal to a specific row of the Y matrix due to the ambiguity of the separation algorithm, the echo distance is obtained by pulse compression of the three rows of data. By comparing it with the prior target information in the search phase, the target's non-deceptive echo can be obtained. Even when the gain difference between the target and the deceptive signal is large and they are at the same angle, they can still be successfully separated, which is difficult to achieve with traditional methods. A comparison will be made later.

[0085] Figure 5 The signal processing results are obtained by the non-pulse code separation algorithm under the same simulation conditions.

[0086] from Figure 5 It can be seen that after the echo signal without pulse coding is separated, the target signal and the interference deception signal are at the same angle, so the signal steering vectors cannot be distinguished from each other. When they are separated at the same angle, the target signal and the interference signal cannot be separated from each other. Figure 5 The time-domain signal diagrams corresponding to the three rows of echo pulses in the Y matrix are shown above. It can be seen from the above figure that it is impossible to clearly distinguish the correspondence between a certain row of echo data and the specific deception interference or target echo signal. Without the method described in this paper, the purpose of separating anti-interference deception cannot be achieved.

[0087] Through the description of specific embodiments, a more in-depth and specific understanding should be gained of the technical means and effects adopted by the present invention to achieve the intended purpose. However, the accompanying drawings are only provided for reference and illustration and are not intended to limit the present invention.

Claims

1. A radar transponder-based range deception jamming suppression method based on pulse coding, characterized in that, include: Step S1: Construct a monostatic one-dimensional linear array MIMO radar. The transmitting array is a uniform linear array with N elements, and the receiving array is a uniform linear array with M elements. The element spacing between the center point of the transmitting array and the center point of the receiving array is d. Within the detection range of the MIMO radar, there are real targets and false targets, and the false targets are range deception interference. Step S2: Determine the phase-coded transmission signal of each element in the transmission array. The weighted encoding of the transmission signal includes the minimum unambiguous radar range and coherent pulse sequence parameters. The transmission signals of any two elements in the transmission array are orthogonal to each other. Step S3: Obtain the received signal of each element in the receiving array; perform matched filtering and conjugate decoding on the received signal of each element in the receiving array to obtain the echo signal of the target with different angles, different distances and different coherent pulse sequence steering vectors within the detection range of the MIMO radar; Step S4: Perform high-dimensional signal processing on the echo signals of different steering vectors after decoding, where different steering vectors represent different target or interference signal echoes; Step S5: Based on the distance or angle information of the signal, the target signal and the interference signal are preserved and suppressed respectively; The radar employs a monostatic MIMO one-dimensional linear array system. M Dimensional launch array element, N Dimensional receiving array elements, element spacing d Given a half-wavelength, the number of coherent pulses for signal processing is: K， The angle between the far-field desired detection target and the array element is During the launch m The signal of each array element is represented as follows: in This is a rectangular window function, representing the window shape function for a pulse signal. Indicates the pulse width, the first m The orthogonal waveforms corresponding to each channel are represented as follows: The orthogonality condition is expressed as follows: Construct pulse codes based on different pulse numbers, the first... m Each formation element k The pulse-coded phase of each pulse is represented as: in Let the pulse coding coefficients be... , The frequency increment of the coefficient is much smaller than f0, and Ru represents the maximum unambiguous range corresponding to the radar pulse period T. c represents the speed of light.

2. The radar transponder-based range deception jamming suppression method based on pulse coding according to claim 1, characterized in that, The element spacing d is set to half the wavelength.

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