Multi-channel anti-reconnaissance waveform design method

Abstract

The invention discloses a multichannel anti-reconnaissance waveform design method, which relates to the technical field of electronic countermeasure, and comprises the following steps: constructing a beam forming relationship between a transmitting signal and an expected radar signal waveform according to the expected radar signal waveform and the expected noise signal waveform; constructing a beam forming relationship between the transmitted signal and the expected noise signal waveform; uniformly expressing the beam forming relationship as a matrix form, and combining to obtain the beam forming relationship between the emission signal and the expected radar signal waveform and the expected noise signal waveform; according to the directional diagram constraint, the expected radar signal and the expected noise signal do not interfere with each other, and an optimization problem is constructed; solving the optimization problem to obtain a weight of an expected radar signal and a weight of an expected noise signal; and multiplying the weight of the expected radar signal by the expected radar signal, and multiplying the weight of the noise signal by the expected noise signal to obtain an emission signal of the array element. The anti-reconnaissance capability can be improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic countermeasures technology, specifically relating to a multi-channel anti-reconnaissance waveform design method. Background Technology

[0002] With the rapid development of electronic information technology and signal processing, electronic countermeasures capabilities, such as signal interception, have been greatly enhanced. As offensive and defensive confrontations intensify, and for self-security, vigorous research into anti-radar technology is being conducted. Complete electronic attack systems have been formed, posing greater challenges to radar detection, especially given the strong interception capabilities of enemy reconnaissance receivers. These receivers can intercept and sort radar signals, extract relevant parameters from the sorted signals, obtain crucial information about our radar, and take targeted attack measures. Under these circumstances, the research on waveforms with good anti-reconnaissance performance has become an urgent need in contemporary electronic warfare.

[0003] In their paper "Low Interception Waveform Sequence Design Based on Iterative Quadratic Optimization Algorithm" (Journal of Electronics and Information Technology, 2024, 46(05): 2048-2056), Liu Qiang et al. from the National University of Defense Technology proposed a constant envelope waveform design method based on iterative quadratic optimization for STFT broadband reconnaissance receivers. This method reduces the power interception probability by minimizing the peak energy of subbands in the time and frequency domains and uses Pareto weights to balance low interception performance and autocorrelation performance. In their paper "Segmented LFM Modulation Random Waveform Counter-Reconnaissance Design" (Radar Science and Technology, 2015, 13(06): 577-586+591), Sun Zhiyong et al. from the PLA Electronic Engineering Academy proposed a segmented LFM modulation random waveform design method. This method segments the pulse and performs inter-segment LFM phase modulation in a random noise background, making the entire pulse exhibit noise-like characteristics in both the time and frequency domains, making it difficult for the reconnaissance receiver to identify. The radar itself uses known inter-segment modulation parameters to achieve normal target detection through frequency domain inter-segment matching or time domain decimation matching. However, none of the above methods fully utilize the spatial dimension freedom brought by multi-channel array antennas. They only start from the time-frequency characteristics of a single waveform, and the counter-reconnaissance methods are relatively simple.

[0004] Therefore, there is an urgent need to provide a multi-channel anti-reconnaissance waveform design method to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a multi-channel anti-reconnaissance waveform design method. The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a multi-channel anti-reconnaissance waveform design method, comprising: Based on the desired radar signal waveform and the desired noise signal waveform, a beamforming relationship is constructed between the transmitted signal and the desired radar signal waveform, as well as between the transmitted signal and the desired noise signal waveform; The beamforming relationship between the transmitted signal and the desired radar signal waveform, as well as the beamforming relationship between the transmitted signal and the desired noise signal waveform, are uniformly expressed in matrix form and merged to obtain the beamforming relationship between the transmitted signal and the desired radar signal waveform and the desired noise signal waveform. Based on the radiation pattern constraints, an optimization problem is constructed to ensure that the desired radar signal and the desired noise signal do not interfere with each other. The optimization problem is solved to obtain the weights of the desired radar signal and the weights of the desired noise signal; Multiply the weights of the desired radar signal by the desired radar signal, and multiply the weights of the noise signal by the desired noise signal to obtain the transmitted signal of the array element, so that the transmitted signal forms a main lobe in the radar direction and a notch in the direction of the enemy's reconnaissance receiver.

[0006] The beneficial effects of this invention are: This invention provides a multi-channel anti-reconnaissance waveform design method. By constraining the transmitted signal energy under certain conditions and satisfying directional constraints, it avoids wasting ineffective energy and ensures efficient utilization of transmitted energy by the radar transmitting array system under limited power conditions. The method designs desired radar signal weights and desired noise signal weights to directionally distribute energy to a specified direction. In the time-frequency domain, the main lobe synthesizes a narrowband linear frequency modulated signal, and the notch synthesizes a broadband noise signal, concentrating energy on the space-time-frequency unit of interest. In this way, while ensuring the radar main lobe detection capability, it reduces energy radiation in the direction of enemy interception, lowers the probability of being detected and intercepted by the enemy, and improves anti-reconnaissance capability.

[0007] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0008] Figure 1 This is a flowchart of a multi-channel anti-reconnaissance waveform design method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram comparing the multi-channel anti-reconnaissance waveform transmission pattern with the phased array transmission pattern provided in an embodiment of the present invention; Figure 3 This is a schematic diagram comparing the main lobe energy of the multi-channel anti-reconnaissance waveform with the main lobe energy of the phased array provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the synthesized signal and the desired signal within the main lobe of the multi-channel anti-reconnaissance waveform provided in an embodiment of the present invention; Figure 5This is a schematic diagram of a multi-channel counter-reconnaissance waveform signal synthesized by an enemy reconnaissance receiver according to an embodiment of the present invention. Detailed Implementation

[0009] 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.

[0010] Please see Figure 1 , Figure 1 This is a flowchart of a multi-channel anti-reconnaissance waveform design method provided by an embodiment of the present invention. The multi-channel anti-reconnaissance waveform design method provided by the present invention includes: S101. Based on the desired radar signal waveform and the desired noise signal waveform, construct the beamforming relationship between the transmitted signal and the desired radar signal waveform, and construct the beamforming relationship between the transmitted signal and the desired noise signal waveform.

[0011] Specifically, in this embodiment, multi-channel anti-reconnaissance waveform design is performed under a uniformly arranged transmitting array element, with the transmitting array element spacing being [missing information]. Assuming the transmitted signal loaded on each transmitting element is This refers to the transmitted signal that is ultimately to be acquired. Based on the desired radar signal waveform, the beamforming relationship between the transmitted signal and the desired radar signal waveform is constructed, which is expressed as: ; in, Indicates the wavelength of the carrier frequency signal. The set of angles within the main lobe of the radar direction. This represents the desired radar signal waveform. Indicates the number of elements in the transmitting array. Indicates the index of the transmitting array element. Indicates the spacing between the transmitting array elements. The first angle in the set of angles within the main lobe of the radar direction. From one angle, Represents a time variable. This indicates the transmit signal loaded on the transmit array element.

[0012] Furthermore, based on the desired noise signal waveform, the beamforming relationship between the transmitted signal and the desired noise signal waveform is constructed, which is expressed as: ; in, Indicates the wavelength of the carrier frequency signal. Indicates the first A set of intercepted direction angles, Indicates the desired noise signal waveform. Indicates the first A specific angle within a set of intercepted direction angles. Indicates the index of the set of intercepted direction angles. This represents the total number of sets of intercepted direction angles. This indicates the transmit signal loaded on the transmit array element.

[0013] S102. The beamforming relationship between the transmitted signal and the desired radar signal waveform, and the beamforming relationship between the transmitted signal and the desired noise signal waveform are uniformly expressed in matrix form and merged to obtain the beamforming relationship between the transmitted signal and the desired radar signal waveform and the desired noise signal waveform.

[0014] Specifically, in this embodiment, the beamforming relationship between the matrix-form transmitted signal and the desired radar signal waveform is expressed as follows: ; ; ; in, express 3D signal matrix, express Dimension's desired radar signal, Indicates transpose. This indicates the conjugate transpose. Represents the imaginary unit. Indicates the transmitting array in The directional guide vector.

[0015] Furthermore, the beamforming relationship between the transmitted signal in matrix form and the desired noise signal waveform is expressed as: ; ; ; in, express 3D signal matrix, express The expected noise signal of dimension, This indicates the conjugate transpose. Indicates transpose. Represents the imaginary unit. Indicates the transmitting array in The directional guide vector.

[0016] Furthermore, in this embodiment, the beamforming relationship between the transmitted signal, the desired radar signal waveform, and the desired noise signal waveform is expressed as follows: ; ; ; in, This represents the set of desired radar signals and desired noise signals. middle The number of ones equals The number of elements in the set. This represents a specific angle within the set of the first intercepted direction angles. This represents the set of the first intercepted direction angles. Indicates the first A specific angle within a set of intercepted direction angles. Indicates the first A set of intercepted direction angles, This represents a guidance matrix composed of multiple directional guidance vectors stacked together.

[0017] S103. Based on the radiation pattern constraints, construct an optimization problem to ensure that the desired radar signal and the desired noise signal do not interfere with each other.

[0018] Specifically, in this embodiment, by designing the transmitted signal matrix, the desired radar signal and desired noise signal can be generated in the desired radar direction and the direction of the opposing reconnaissance receiver, respectively, while minimizing the mutual interference between them. To this end, weights for the desired radar signal and desired noise signal are designed respectively, wherein the weight of the desired radar signal is denoted as... The desired noise signal weights are denoted as The optimization problem is constructed by using the following constraints to avoid mutual interference: the desired radar signal weights forming a main lobe in the desired radar direction, the desired radar signal weights forming a notch in the direction of the enemy reconnaissance receiver, the desired noise signal weights forming a notch in the direction of the main lobe, and the desired noise signal weights forming a main lobe in the direction of the enemy reconnaissance receiver.

[0019] Furthermore, the optimization problem can be expressed as: ; ; in, This represents the desired radar signal weights. Represents the desired noise signal weights. express Dimension's desired radar signal, express The expected noise signal of dimension, Indicates transpose. This indicates the conjugate transpose. The set of angles within the main lobe of the radar direction. The first angle in the set of angles within the main lobe of the radar direction. From one angle, Indicates the first A set of intercepted direction angles, Indicates the first A specific angle within a set of intercepted direction angles. Indicates the first A specific angle within a set of intercepted direction angles. Indicates the first A set of intercepted direction angles, Indicates the array steering vector. This represents the total number of sets of intercepted direction angles. This indicates the expected depth of the energy notch in the direction of the enemy's reconnaissance receiver. This represents the squared Frobenius norm.

[0020] S104. Solve the optimization problem to obtain the weights of the desired radar signal and the desired noise signal.

[0021] Specifically, in this embodiment, in order to ensure that the noise signal does not interfere with the radar signal throughout the entire main lobe area of ​​the radar, it is necessary to [implement measures] the entire main lobe region of the radar. The radiation pattern within the main lobe is restricted, meaning the noise radiation pattern is 0 within the main lobe region, indicating that the signal within the main lobe is free of noise.

[0022] Furthermore, the desired weights of the radar signals Represented as: ;

[0023] in, This represents a guidance matrix composed of multiple directional guidance vectors stacked together. This indicates the conjugate transpose. Indicates transpose. This represents the constrained response vector of the desired radar signal; Weights of the desired noise signal Represented as: ; in, This represents the constraint response vector of the desired noise signal.

[0024] S105. Multiply the weight of the desired radar signal with the desired radar signal, and multiply the weight of the noise signal with the desired noise signal to obtain the transmitted signal of the array element, so that the transmitted signal forms a main lobe in the radar direction and a notch in the direction of the enemy's reconnaissance receiver.

[0025] Specifically, in this embodiment, the transmission signal of the array element Represented as: ; in, This indicates the radar signal portion. This indicates the noise component.

[0026] In summary, the multi-channel anti-reconnaissance waveform design method provided by this invention has the following beneficial effects: First, this invention utilizes a transmitting array to introduce... The system uses 3D spatial degrees of freedom to accurately characterize the spatial differences in different directions through arrayed steering vectors, enabling main lobe detection and notch counter-reconnaissance. The Frobenius norm is used as the total transmitted energy metric. By minimizing the objective function, the system avoids wasting ineffective energy while satisfying directional constraints. By designing different weights, the energy is allocated to specified directions. In the time-frequency domain, the main lobe synthesizes a narrowband linear frequency modulated signal, and the notch synthesizes a broadband noise signal.

[0027] Secondly, while ensuring the radar's main lobe direction detection capability, this invention reduces energy radiation in the direction of enemy interception, thereby lowering the probability of being intercepted by the enemy and improving counter-reconnaissance capabilities.

[0028] In an optional embodiment of the present invention, the effectiveness of the multi-channel anti-reconnaissance waveform design method provided in the above embodiment is verified by simulation experiments, specifically as follows: I. Simulation Conditions The simulation experiment in this embodiment was conducted in the MATLAB R2024a software environment.

[0029] II. Simulation Content and Result Analysis Consider a multi-channel linear array radar that uses both transmit and receive signals. Each channel contains several array elements. Assume that while the radar is detecting targets in a distant area, a malicious reconnaissance receiver is conducting sidelobe reconnaissance of the radar's transmitted signal at a sidelobe location. After preliminary airspace search, the range of the malicious reconnaissance receiver's location is known, but its exact location cannot be obtained. In this scenario, a multi-channel anti-reconnaissance waveform is used to improve the radar's anti-reconnaissance performance in multiple ways. The anti-reconnaissance performance of this method is verified through simulation experiments. Specific simulation parameters are shown in Table 1.

[0030] Table 1 Simulation parameters for multi-channel counter-reconnaissance waveform design

[0031] Please see Figure 2 , Figure 2This is a schematic diagram comparing the multi-channel counter-reconnaissance waveform transmission pattern with the phased array transmission pattern provided in this embodiment of the invention. In this embodiment, a detection signal with high energy is synthesized on the main lobe, forming a -42dB notch in the direction of the opponent's reconnaissance receiver, reducing the energy radiation in the direction of interception by the opponent, lowering the probability of being intercepted by the opponent, and improving the counter-reconnaissance capability.

[0032] Please see Figure 3 , Figure 3 This is a schematic diagram comparing the main lobe energy of the multi-channel anti-reconnaissance waveform with that of the phased array provided in this embodiment of the invention. When the main lobe points to 0°, and the enemy reconnaissance receiver is within the range of 10° to 13°, the main lobe energy loss is only 0.35dB, ensuring the detection capability of the multi-channel anti-reconnaissance waveform.

[0033] Please see Figure 4 , Figure 4 This is a schematic diagram of the synthesized signal and the desired signal within the main lobe of the multi-channel anti-reconnaissance waveform provided in an embodiment of the present invention. It can be seen that the desired signal of the main lobe is a linear frequency modulated (LFM) signal, and the synthesized signal of the main lobe is also a LFM signal.

[0034] Please see Figure 5 , Figure 5 This is a schematic diagram of a multi-channel anti-reconnaissance waveform synthesized in the direction of the enemy reconnaissance receiver provided in an embodiment of the present invention. A noise signal is formed in the direction of the enemy reconnaissance receiver, making it impossible for the enemy reconnaissance receiver to sort and identify our detection signal. Ultimately, the anti-reconnaissance performance of the radar is improved from both the aspects of transmission energy and waveform.

[0035] 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 multi-channel anti-reconnaissance waveform design method, characterized in that, include: Based on the desired radar signal waveform and the desired noise signal waveform, a beamforming relationship is constructed between the transmitted signal and the desired radar signal waveform, and a beamforming relationship is also constructed between the transmitted signal and the desired noise signal waveform. The beamforming relationship between the transmitted signal and the desired radar signal waveform, and the beamforming relationship between the transmitted signal and the desired noise signal waveform are uniformly expressed in matrix form and combined to obtain the beamforming relationship between the transmitted signal and the desired radar signal waveform and the desired noise signal waveform. Based on the radiation pattern constraints, an optimization problem is constructed to ensure that the desired radar signal and the desired noise signal do not interfere with each other. The optimization problem is solved to obtain the weights of the desired radar signal and the weights of the desired noise signal; The weights of the desired radar signal are multiplied together, and the weights of the noise signal are multiplied together with the desired noise signal to obtain the transmitted signal of the array element, such that the transmitted signal forms a main lobe in the radar direction and a notch in the direction of the enemy's reconnaissance receiver.

2. The multi-channel anti-reconnaissance waveform design method according to claim 1, characterized in that, Based on the desired radar signal waveform, the beamforming relationship between the transmitted signal and the desired radar signal waveform is expressed as follows: ； in, Indicates the wavelength of the carrier frequency signal. The set of angles within the main lobe of the radar direction. This represents the desired radar signal waveform. Indicates the number of elements in the transmitting array. Indicates the index of the transmitting array element. Indicates the spacing between the transmitting array elements. The first angle in the set of angles within the main lobe of the radar direction. From one angle, Represents a time variable. This indicates the transmit signal loaded on the transmit array element.

3. The multi-channel anti-reconnaissance waveform design method according to claim 2, characterized in that, Based on the desired noise signal waveform, the beamforming relationship between the transmitted signal and the desired noise signal waveform is expressed as follows: ； in, Indicates the wavelength of the carrier frequency signal. Indicates the first A set of intercepted direction angles, Indicates the desired noise signal waveform. Indicates the first A specific angle within a set of intercepted direction angles. Indicates the index of the set of intercepted direction angles. This represents the total number of sets of intercepted direction angles.

4. The multi-channel anti-reconnaissance waveform design method according to claim 3, characterized in that, The beamforming relationship between the transmitted signal and the desired radar signal waveform in matrix form is expressed as follows: ； ； ； in, express 3D signal matrix, express Dimension's desired radar signal, Indicates transpose. This indicates the conjugate transpose. Represents the imaginary unit. Indicates the transmitting array in The directional guide vector.

5. The multi-channel anti-reconnaissance waveform design method according to claim 4, characterized in that, The beamforming relationship between the transmitted signal and the desired noise signal waveform in matrix form is expressed as follows: ； ； ； in, express 3D signal matrix, express The expected noise signal of dimension, Indicates the transmitting array in The directional guide vector.

6. The multi-channel anti-reconnaissance waveform design method according to claim 5, characterized in that, The beamforming relationship between the transmitted signal, the desired radar signal waveform, and the desired noise signal waveform is expressed as follows: ； ； ； in, This represents the set of desired radar signals and desired noise signals. This represents a specific angle within the set of the first intercepted direction angles. This represents the set of the first intercepted direction angles. Indicates the first A specific angle within a set of intercepted direction angles. Indicates the first A set of intercepted direction angles, This represents a guidance matrix composed of multiple directional guidance vectors stacked together.

7. The multi-channel anti-reconnaissance waveform design method according to claim 1, characterized in that, An optimization problem is constructed using the following pattern constraints: the desired radar signal weights forming a main lobe in the desired radar direction, the desired radar signal weights forming a notch in the direction of the enemy reconnaissance receiver, the desired noise signal weights forming a notch in the direction of the main lobe, and the desired noise signal weights forming a main lobe in the direction of the enemy reconnaissance receiver.

8. The multi-channel anti-reconnaissance waveform design method according to claim 7, characterized in that, The optimization problem is expressed as: ； ； in, This represents the desired radar signal weights. Represents the desired noise signal weights. express Dimension's desired radar signal, express The expected noise signal of dimension, Indicates transpose. This indicates the conjugate transpose. The set of angles within the main lobe of the radar direction. The first angle in the set of angles within the main lobe of the radar direction. From one angle, Indicates the first A set of intercepted direction angles, Indicates the first A specific angle within a set of intercepted direction angles. Indicates the first A specific angle within a set of intercepted direction angles. Indicates the first A set of intercepted direction angles, Indicates the array steering vector. This represents the total number of sets of intercepted direction angles. This indicates the expected depth of the energy notch in the direction of the enemy's reconnaissance receiver. This represents the square of the Frobenius norm.

9. The multi-channel anti-reconnaissance waveform design method according to claim 8, characterized in that, The weight of the desired radar signal Represented as: ； in, This represents a guidance matrix composed of multiple directional guidance vectors stacked together. This represents the constrained response vector of the desired radar signal; The weights of the desired noise signal Represented as: ； in, This represents the constraint response vector of the desired noise signal.

10. The multi-channel anti-reconnaissance waveform design method according to claim 9, characterized in that, The transmission signal of the array element Represented as: ； in, This indicates the radar signal portion. This indicates the noise component.

Images