High-precision cross-eye interference system based on light delay

Abstract

The invention discloses a high-precision cross-eye interference system based on optical delay, which belongs to the technical field of radars, and comprises the following steps: a receiving end of a receiving antenna receives an emission signal of a monopulse radar; the transmitting end of the receiving antenna is connected with the input end of the low-noise amplifier, the output end of the low-noise amplifier is connected with the input end of the controllable attenuator, and the output end of the controllable attenuator is connected with the input end of the power divider; the first output end of the power divider is connected with the receiving end of the first transmitting antenna; the second output end of the power divider is connected with the input end of the E / O electro-optical conversion module, the output end of the E / O electro-optical conversion module is connected with the input end of the controllable optical delay module, the output end of the controllable optical delay module is connected with the input end of the O / E photoelectric conversion module, and the output end of the O / E photoelectric conversion module is connected with the receiving end of the second transmitting antenna. The transmitting end of the first transmitting antenna and the transmitting end of the second transmitting antenna transmit two paths of signals which are equal in amplitude and opposite in phase, cross-eye interference is combined with optical fibers, and the transmission precision of interference signals is stably and accurately adjusted.

Description

Technical Field

[0001] This invention belongs to the field of radar technology, specifically relating to a high-precision cross-eye jamming system based on optical delay. Background Technology

[0002] In modern warfare, radar, as a crucial detection device, plays a key role in the military field due to its powerful target detection and localization capabilities. Monopulse radar, with its high-precision angle measurement technology and strong anti-jamming capabilities, is widely used in critical aspects such as weapon guidance and target tracking, becoming one of the core pieces of equipment ensuring the accuracy and effectiveness of military operations.

[0003] With the continuous advancement of military technology, the battlefield environment has become increasingly complex, leading to more intense radar jamming and counter-jamming efforts. Traditional jamming methods are gradually becoming inadequate to meet operational demands in the face of ever-evolving radar technology. Monopulse radar possesses strong resistance to single-point source jamming, effectively identifying and eliminating simple interference signals while maintaining stable target tracking. This has prompted military researchers to continuously explore more effective jamming techniques to penetrate monopulse radar defenses and gain battlefield advantage.

[0004] Against this backdrop, cross-eye jamming technology emerged. As an effective jamming method against monopulse radar, cross-eye jamming simulates angular scintillation by deploying multiple jamming sources in space and precisely controlling the amplitude and phase relationship of each source's signal. This causes wavefront distortion in the radar's received echo signal, resulting in significant deviations in angle measurement and preventing accurate target locking. Compared to other jamming techniques, cross-eye jamming has unique advantages. It operates within the main lobe range of monopulse radar, exhibiting significant jamming effects and high deceptiveness, causing substantial angular errors in the radar and effectively protecting the jammed target.

[0005] Since its inception, cross-eye jamming technology has continuously evolved. From initial theoretical research to practical applications, researchers have constantly optimized its jamming mechanism and implementation methods. Early on, due to technological limitations, cross-eye jamming faced numerous challenges in areas such as phase control, leading to unstable jamming effects. With the emergence of key technologies such as Digital Radio Frequency Memory (DRFM), the parameter control of cross-eye jamming has become more precise and stable, greatly enhancing its application value in actual combat. Currently, cross-eye jamming technology has been applied in various military scenarios, becoming an important means of countering monopulse radar in the field of electronic warfare. However, with the continuous development of radar technology, cross-eye jamming also faces new challenges, such as further enhancing radar anti-jamming capabilities and accurately identifying jamming sources. This has prompted the technology to continuously seek new breakthroughs and development.

[0006] Existing cross-eye robust angle deception methods based on triplet antennas employ a triplet-structured jamming antenna array, combined with adaptive genetic factor optimization, to constrain both the deception waveform and direction of arrival (DOA). At the jamming signal transmitter, the triplet structure enhances focusing performance and reduces deception disturbances from the linear array's symmetrical peaks. At the signal processing end, AGA optimization of complex weighting coefficients achieves stable deception and expands the angle deception coverage. However, in complex electromagnetic environments, signal transmission is susceptible to interference, affecting the stability and accuracy of the deception angle. Employing waveform matching and beam pointing constraints, combined with adaptive genetic algorithm optimization, increases the system's implementation complexity. While improvements are made in angle deception coverage, long-distance jamming is difficult due to signal transmission attenuation limitations.

[0007] Existing dynamic cross-eye jamming schemes based on dynamically controlling the power and phase of the jamming sources utilize a reverse antenna structure to compensate for the phase difference introduced by the path difference. During jamming, the transmit power and phase of the two jamming sources are dynamically adjusted in single or multiple cycles, ensuring that the radar is always subjected to strong interference at certain times within each cycle, leading to tracking non-convergence and instability. This reduces the requirement for precise control of the jamming amplitude and phase, achieving effective jamming of monopulse radar. However, in practice, precise control is difficult due to factors such as platform motion, sampling, and clock asynchrony. Traditional transmission methods are susceptible to electromagnetic interference, leading to signal attenuation and distortion, affecting the jamming effect. The jamming device of this method consists of multiple parts, resulting in a relatively complex structure that may affect the system's integration and stability.

[0008] Furthermore, in the study of Doppler frequency differences in multi-loop reverse cross-eye jamming, the Doppler frequency differences between different jamming loops caused by the movement of the jamming platform and their impact on the jamming effect were investigated. A mathematical model was established, the expression for the Doppler frequency difference was derived, and a compensation method was proposed. The drawback is the need for high-precision real-time measurement of the jammer's speed, angle of rotation, and distance, and rapid calculation of the compensated phase difference, making system implementation difficult. Platform movement causes Doppler frequency differences between different loops in multi-loop reverse cross-eye jamming, which may lead to cross-eye jamming being identified by radar, weakening the jamming effect, or even turning the jammer into a beacon.

[0009] The aforementioned existing methods all require ensuring the stability and accuracy of the deception angle to guarantee the jamming effect. Currently, there is an urgent need to address the issues of poor phase synchronization accuracy, signal transmission stability, and deployment flexibility in existing radar cross-eye jamming technologies. Summary of the Invention

[0010] The purpose of this invention is to overcome the problems of poor phase synchronization accuracy, signal transmission stability and deployment flexibility of existing radar cross-eye jamming technology, and to propose a high-precision cross-eye jamming system based on optical delay.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a high-precision cross-eye interference system based on optical delay, comprising a receiving antenna, a first transmitting antenna, a second transmitting antenna, a low-noise amplifier, a controllable attenuator, a power divider, an E / O electro-optical conversion module, a controllable optical delay module, and an O / E optoelectronic conversion module; The receiving antenna receives the transmitted signal from the monopulse radar; the transmitting end of the receiving antenna is connected to the input of a low-noise amplifier, the output of the low-noise amplifier is connected to the input of a controllable attenuator, and the output of the controllable attenuator is connected to the input of a power divider. The first output terminal of the power divider is connected to the receiving terminal of the first transmitting antenna; the second output terminal of the power divider is connected to the input terminal of the E / O electro-optic conversion module, the output terminal of the E / O electro-optic conversion module is connected to the input terminal of the controllable optical delay module, the output terminal of the controllable optical delay module is connected to the input terminal of the O / E opto-optic conversion module, and the output terminal of the O / E opto-optic conversion module is connected to the receiving terminal of the second transmitting antenna. The transmitting terminals of the first and second transmitting antennas transmit two signals with equal amplitude and opposite phase.

[0012] Furthermore, the power divider splits the received signal into two output signals. One output signal goes directly to the receiving end of the first transmitting antenna with a delay of 0, while the other output signal goes through the electro-optical conversion module, the controllable optical delay module, and the photoelectric conversion module, with a delay of 180°, to the receiving end of the second transmitting antenna.

[0013] Furthermore, the bandwidth of the power divider is 1GHz-40GHz.

[0014] Furthermore, the bandwidth of both the E / O optoelectronic conversion module and the O / E optoelectronic conversion module is 1GHz-40GHz.

[0015] Furthermore, the bandwidth of the low-noise amplifier is 1GHz-40GHz.

[0016] Furthermore, the bandwidth with controllable attenuation is 1GHz-40GHz.

[0017] Furthermore, the combined gain of the low-noise amplifier and the controllable attenuator is adjustable from 1dB to 120dB.

[0018] Furthermore, the controllable optical delay module accepts input signals from 1GHz to 40GHz. The maximum delay of the controllable optical delay module is 1500ps, and the maximum delay accuracy is 0.05ps. The delay time of the controllable optical delay module is obtained using the following formula:

[0019] in, Indicates the delay time. Indicates the frequency of the signal to be delayed. This indicates the phase corresponding to the delay.

[0020] Secondly, the present invention provides an operation method for a high-precision cross-eye interference system based on optical delay, comprising the following steps: After receiving the signal from the monopulse radar, the receiving antenna reduces the noise figure through a low-noise amplifier. The amplitude of the signal is controlled by a controllable attenuator, and the amplitude-controlled signal is divided into two output signals by a power divider. One output signal arrives at the receiving end of the first transmitting antenna with a delay of 0, while the other output signal arrives at the receiving end of the second transmitting antenna after a delay of 180° through an E / O electro-optical conversion module, a controllable optical delay module, and an O / E photoelectric conversion module. The first and second transmitting antennas then transmit two signals with equal amplitude and opposite phase.

[0021] Thirdly, the present invention provides a method for interfering with the angle measurement of a single-pulse radar, employing a high-precision cross-eye interference system based on optical delay, comprising the following steps: After receiving the angle measurement signal transmitted by the monopulse radar, the system processes the angle measurement signal and transmits two signals with equal amplitude and opposite phase. After receiving the two transmitted signals with equal amplitude and opposite phase, the monopulse radar uses the sum and difference signals to compare the angle measurement method to generate an angle measurement error, thus interfering with the angle measurement of the monopulse radar.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects: This invention proposes a high-precision cross-eye interference system based on optical delay. It combines cross-eye interference with fiber optic technology, leveraging the stable transmission characteristics of fiber optics to precisely adjust the transmission accuracy of the interference signal, reducing errors and improving system reliability and stability. Furthermore, many current solutions, in pursuit of performance enhancement, often result in high system complexity. Utilizing fiber optic delay lines to precisely adjust the phase of the interference signal is simpler and more accurate than traditional phase control methods, simplifying some complex algorithms and control processes. The received signal is amplified, amplitude-modulated, and split, resulting in stable and flexible processing. The optical delay module achieves high-precision delay control, accurately adjusting the phase. Equal-amplitude, anti-phase signals are emitted to interfere with radar angle measurement, reducing its tracking and positioning capabilities. The system is compact, reliable, and an efficient means of countering monopulse radar. Attached Figure Description

[0023] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. In the drawings: Figure 1 This is a schematic diagram of a high-precision cross-eye interference system based on optical delay.

[0024] Figure 2 This is a flowchart illustrating the process from radar signal transmission to cross-eye interference and then to radar signal reception.

[0025] Figure 3 This is a schematic diagram of the interference signals and echoes intercepted by the radar receiver.

[0026] Figure 4 This is a vector diagram of cross-eye interference and difference signals under ideal conditions.

[0027] Figure 5 This is a vector diagram of suboptimal cross-eye interference and poor signal. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] Example 1 See Figure 1 A high-precision cross-eye interference system based on optical delay includes a receiving antenna, a first transmitting antenna, a second transmitting antenna, a low-noise amplifier, a controllable attenuator, a power divider, an E / O electro-optical conversion module, a controllable optical delay module, and an O / E optoelectronic conversion module. The receiving antenna receives the transmitted signal from the monopulse radar; the transmitting end of the receiving antenna is connected to the input of a low-noise amplifier, the output of the low-noise amplifier is connected to the input of a controllable attenuator, and the output of the controllable attenuator is connected to the input of a power divider. The first output terminal of the power divider is connected to the receiving terminal of the first transmitting antenna; the second output terminal of the power divider is connected to the input terminal of the E / O electro-optic conversion module, the output terminal of the E / O electro-optic conversion module is connected to the input terminal of the controllable optical delay module, the output terminal of the controllable optical delay module is connected to the input terminal of the O / E opto-optic conversion module, and the output terminal of the O / E opto-optic conversion module is connected to the receiving terminal of the second transmitting antenna. The transmitting terminals of the first and second transmitting antennas transmit two signals with equal amplitude and opposite phase.

[0032] In this embodiment, after the receiving antenna receives the signal transmitted by the monopulse radar, it is amplified by a low-noise amplifier, the signal strength is adjusted by a controllable attenuator, and then split by a power divider, ensuring the stability and flexibility of signal processing. A combination of an E / O electro-optical conversion module, a controllable optical delay module, and an O / E opto-optical conversion module is used, leveraging optical delay technology to achieve high-precision signal delay control, enabling precise adjustment of the phase relationship between the two signals. The first and second transmitting antennas transmit two signals of equal amplitude and opposite phase, effectively interfering with the angle measurement system of the monopulse radar, making it difficult for it to accurately determine the target angle and significantly reducing the radar's tracking and positioning capabilities. The entire system is compact and reliable, and through the ingenious combination of light and electricity, it has unique advantages in improving the accuracy and effectiveness of interference, providing an efficient means to counter monopulse radar.

[0033] Example 2 A method for operating a high-precision cross-eye interference system based on optical delay, using the high-precision cross-eye interference system based on optical delay in Example 1, includes the following steps: After receiving the signal from the monopulse radar, the receiving antenna reduces the noise figure through a low-noise amplifier. The amplitude of the signal is controlled by a controllable attenuator, and the amplitude-controlled signal is divided into two output signals by a power divider. One output signal arrives at the receiving end of the first transmitting antenna with a delay of 0, while the other output signal arrives at the receiving end of the second transmitting antenna after a delay of 180° through an E / O electro-optical conversion module, a controllable optical delay module, and an O / E photoelectric conversion module. The first and second transmitting antennas then transmit two signals with equal amplitude and opposite phase.

[0034] In this embodiment, the received signal is first reduced by a low-noise amplifier and modulated by a controllable attenuator to ensure appropriate signal quality and strength. Then, it is split by a power divider, one path goes directly to the target signal, and the other path is delayed by 180° optically before finally transmitting an equal-amplitude, inverse signal. This can effectively interfere with the angle measurement of monopulse radar, providing accuracy and flexibility.

[0035] Example 3 See Figure 2 A method for interfering with monopulse radar angle measurement, employing a high-precision cross-eye jamming system based on optical delay as described in Example 1, includes the following steps: After receiving the angle measurement signal transmitted by the monopulse radar, the system processes the angle measurement signal and transmits two signals with equal amplitude and opposite phase. After receiving the two transmitted signals with equal amplitude and opposite phase, the monopulse radar uses the sum and difference signals to compare the angle measurement method to generate an angle measurement error, thus interfering with the angle measurement of the monopulse radar.

[0036] This embodiment utilizes a high-precision cross-eye jamming system based on optical delay, which can accurately process the angle measurement signal of a monopulse radar and transmit equal-amplitude, inverse-phase signals. This causes errors when the radar uses sum and difference signals to measure angles, effectively disrupting its angle measurement function. The jamming method is efficient and precise, enhancing the ability to counter monopulse radar.

[0037] Example 4 A high-precision cross-eye interference system based on optical delay. Figure 1 This is a schematic diagram of the working principle of this embodiment. After the receiving antenna receives the signal, it is suppressed by a low-noise amplifier to suppress the influence of noise on the subsequent system. The signal amplitude is controlled by a controllable attenuator, and the power divider splits the signal into two paths. One path is directly transmitted through a wire, and the other path is transmitted through an electro-optical conversion module, a controllable optical delay module, and a photoelectric conversion module to delay the signal on the optical path, so as to achieve more precise control of the phase. Finally, two signals with the same amplitude but opposite phase are transmitted.

[0038] Figure 2This is a flowchart showing the process from radar signal transmission to cross-eye interference and then to radar signal reception. Figure 1 The part shown is the structure of the cross eye, corresponding to Figure 2 The process involves four stages: the cross-eye receiving antenna receives the signal, the cross-eye processes the signal, the cross-eye transmitting antenna emits the jamming signal, and the monopulse radar receives the jammed signal. The entire process is as follows: the monopulse radar first transmits a signal to prepare for angle measurement. After an object equipped with a cross-eye jamming device detects the signal, it processes the signal and finally emits two signals of equal amplitude but opposite phase. When the radar receives these signals, the angle measurement method, which compares the sum and difference signals, introduces a very large error, thus interfering with the angle measurement accuracy of the monopulse radar.

[0039] like Figure 3 The diagram shows the interference signal and echo intercepted by the radar receiver when cross-eye interference is present. The radar's angle measurement processing is as follows when cross-eye interference is absent: Monopulse radar determines the direction of a target by comparing signals from two or more receiving channels. Specifically, monopulse radar uses a sum channel (Σ) and a difference channel (Δ) to calculate the target's azimuth and elevation. The sum channel is the sum of the signals from all receiving channels, and the difference channel is the difference between the signals from the receiving channels.

[0040] Assume that the signal received by the monopulse radar consists only of the target echo and contains no interference signals. The received signal can be expressed as:

[0041]

[0042] Where Ar is the target signal amplitude, F(θ) is the antenna pattern function, θ0 is the angle between the direction of maximum gain of a single beam and the direction of the radar signal of equal strength, and θ3 is the angle between the target echo and the direction of the radar signal of equal strength.

[0043] The sum and difference signals can be represented as:

[0044]

[0045] The error signal Se(t) reflects the deviation between the target direction and the current antenna pointing. By adjusting the antenna pointing, the error signal approaches zero, thus achieving accurate target tracking. For a monopulse radar, the error signal Se(t) can be expressed as:

[0046] In the absence of cross-eye interference, a monopulse radar will calculate and signal E Σ Sum and difference signals E Then, the error signal Se(t) is calculated, and the antenna direction is adjusted according to the error signal Se(t) to make the error signal approach zero. When the error signal is zero, the antenna direction is consistent with the target direction, thereby achieving accurate target tracking.

[0047] When cross-eye interference is present (J1 and J2 are present), the received signal can be expressed as:

[0048]

[0049] Where A1 and A2 are the amplitudes of the interference signal, A r Let F(θ) be the target signal amplitude, F(θ) be the antenna pattern function, θ1 and θ2 be the angles of the interference signal relative to the radar pointing direction, and θ3 be the angle between the target echo and the direction of the radar signal of equal strength (radar pointing direction). From this, the sum beam and difference beam can be obtained:

[0050]

[0051] The error signal Se(t) for a single-pulse radar can be expressed as:

[0052] Assume that the antenna pattern function F(θ) can be linearly approximated in the vicinity of θ0 as follows:

[0053] If we substitute the above approximation into the error signal formula, we can obtain:

[0054] When the error function Se(t) = 0, the radar pointing angle deviation θ' can be expressed as:

[0055] This formula describes the relationship between the pointing angle deviation θ' of a monopulse radar and several parameters under cross-eye jamming conditions. By adjusting these parameters, the effect of cross-eye jamming can be optimized, causing the radar to point away from the true target position, thereby achieving effective jamming.

[0056] Where α is the angle between the target echo and the angle bisectors of the two interfering sources. The larger α is, the larger the pointing angle deviation θ'. a is the amplitude ratio of the target echo to the interfering signal. The larger a is, the smaller the pointing angle deviation θ'. b is the amplitude ratio of the two interfering signals. The closer b is to 1, the larger the pointing angle deviation θ'. φ1 is the phase difference between the two interfering signals. The closer φ1 is to 180°, the larger the pointing angle deviation θ'. θ is the angle formed by the arrival of the two interfering signals at the radar receiver. The larger θ is, the larger the pointing angle deviation θ' is.

[0057] In radar cross-eye angle deception, the cross-eye requires a high degree of accuracy in both phase and angle; otherwise, the jamming effect will be significantly affected. Figure 4 The diagram shows the cross-eye interference and difference signal vector diagram under ideal conditions.

[0058] Ideally, the two signals S1 and S2 received by a monopulse radar should be of equal amplitude and opposite phase. Such equal amplitude and opposite phase signals would cause errors in the sum-difference beam angle measurement system of the monopulse radar, because the sum signal would cancel out, while the difference signal would increase, preventing the radar from accurately measuring the target angle and achieving the purpose of interference. However, due to the difficulty in perfectly matching the radiation pattern of the cross-eye jamming antenna and the wave transmission performance of the jamming radome, coupled with delay and amplitude differences in the processing circuitry of the jamming equipment, the control precision of the phase shifter, and the multipath effects during field calibration of the equipment installed on aircraft or ships, cross-eye jamming cannot achieve ideal equal amplitude and opposite phase. This will lead to an increased difference in the amplitudes A and B of the signals received by the monopulse radar antenna, and the phase difference between the signals received by the two antennas will be less than 180°. Under these conditions, the sum-difference signal vectors are obtained as follows: Figure 5 As shown.

[0059] from Figure 5 As can be seen, the vectors of the sum and difference signals are no longer perpendicular to each other. The effect of the angle deception caused by cross-eye interference is reduced, greatly increasing the likelihood of interference immunity. Therefore, precise amplitude and phase control is essential.

[0060] When the phase difference between the two interfering signals deviates by 180° (e.g., Φ1-Φ2=180°±), When Φ), (assuming A1=A2=A):

[0061]

[0062] At this point, the radar's error signal Se(t) deviates from the ideal value, and the jamming and deception effect weakens.

[0063] Effective interference gain (G) of cross-eye interference 干扰 The angle error is defined as the ratio of the radar angle error to the value under no interference conditions, and it is related to the phase error. The relationship of Φ is:

[0064] Where b is the amplitude ratio of the two signals, and Φ1 is the actual phase difference.

[0065] When the phase difference deviates from 180° (Φ1=180°+) Φ):

[0066] If b=1, when The interference gain is maximum when Φ=0° (ideal 180° phase difference), resulting in significant radar angle error. As Φ increases, the interference gain will decrease rapidly (e.g. When Φ=10°, the gain decreases by approximately 50%. When Φ≥30°, the jamming effect is basically ineffective, and the radar may be able to identify the real target.

[0067] The main schematic diagram of this embodiment is as follows: Figure 1 As shown, this embodiment mainly includes three antennas (one receiver and two transmitters), a low-noise amplifier, a controllable attenuator, a power divider, an E / O electro-optic conversion module, a controllable optical delay module, and an O / E optoelectronic conversion module. After receiving the signal from the monopulse radar, the signal is amplified by the low-noise amplifier to reduce the noise figure and suppress its impact on subsequent systems. The signal amplitude is then controlled by the controllable attenuator, and the power divider splits the signal into two equal paths. These paths then pass through the E / O electro-optic conversion module, the controllable optical delay module, and the O / E optoelectronic conversion module. One path has a zero delay, while the other path's phase is controlled by the electro-optic conversion module, the controllable optical delay module, and the optoelectronic conversion module to delay the signal by 180° before finally reaching the two transmitting antennas. This achieves the transmission of two equal-amplitude, out-of-phase signals.

[0068] The following are the details for each module: Power dividers: The core principle of a power divider is based on electromagnetic wave propagation, transmission line theory, and network analysis, distributing the power of the input signal to each output terminal according to a specific ratio. Power dividers can be divided into passive and active power dividers based on their operating principle and design. Passive power dividers do not require additional power supply support and are mainly based on transmission line theory or resistor networks. Active power dividers have built-in amplifiers or active components, which can compensate for power loss while distributing the signal, but require additional power supply support. This embodiment uses a power divider with a bandwidth of 1GHz-40GHz.

[0069] Optoelectronic conversion module: An optoelectronic conversion module is a key device that converts optical signals and electrical signals to each other, and is widely used in optical communication, sensors, optical measurement, and other fields. Depending on their operating direction, optoelectronic conversion modules can be divided into two categories: optoelectronic detection (optical-to-electrical, O / E) and electro-optical emission (electrical-to-optical, E / O). The core task of electro-to-optic conversion is to modulate an electrical signal into a light wave, and then transmit it through optical fiber. An electro-optic conversion module mainly consists of a driver circuit, a light source, a modulator, and an optocoupler. The principle of optical-to-electrical conversion is to convert the received optical signal into an electrical signal through a photodetector. In this embodiment, an optoelectronic conversion module with a bandwidth of 1GHz-40GHz is used.

[0070] Low-Noise Amplifier: This embodiment uses a low-noise amplifier with a bandwidth of 1GHz-40GHz. A low-noise amplifier (LNA) is an electronic amplifier that amplifies weak signals while minimizing noise. It is widely used in receiving devices such as wireless communication, radar, optical communication, and radio frequency systems. Its performance is crucial to the signal quality and sensitivity of the system. The LNA amplifies the received weak signal to a level that subsequent processing circuits can recognize, and minimizes the noise introduced during amplification to ensure the highest possible signal-to-noise ratio (SNR). The core structure of an LNA includes an input matching network, a gain stage, and an output matching network. The gain stage is typically a multi-stage amplifier, with core components often being field-effect transistors (FETs) or high-electron-mobility transistors (HETs). The amplifier amplifies the signal voltage or current; the gain G is usually expressed as the power gain. (1) Higher gain results in higher signal amplitude, but a balance needs to be struck between noise and linearity. Each amplifier stage introduces a certain amount of noise, typically measured by the noise figure (NF). (2) Signal-to-noise ratio (SNR) is an important indicator of signal quality. The goal of LNA design is to minimize the noise figure of the first-stage amplifier, as it has the greatest impact on the overall system noise figure.

[0071] Attenuator: This embodiment uses a controllable attenuator with a bandwidth of 1GHz-40GHz. A controllable attenuator is a device that can adjust the signal attenuation as needed. It is widely used in radio frequency, microwave communication, electro-optical systems, and other applications to adjust signal strength to meet different system requirements. Controllable attenuators reduce signal strength by adjusting the signal power or amplitude. Specifically, they can be divided into resistor network attenuators, PIN diode attenuators, mechanical attenuators, digitally controllable attenuators, and optical attenuators. In this embodiment, the combination of a low-noise amplifier and a controllable attenuator ultimately achieves an adjustable gain of 1dB-120dB.

[0072] Optical delay unit: An optical delay unit is a device or technology used to delay the propagation of optical signals. In optical communication and optical systems, optical delay units can adjust the propagation time of optical signals to achieve signal synchronization, signal processing, or optimization of optical paths. Optical delay units achieve delay by increasing the distance light travels within them; a delay of up to 1500ps with an accuracy of 0.05ps can be achieved via a PC. This optical delay unit supports signal input delays from 1GHz to 40GHz; the same delay will result in different phase differences for signals of different frequencies. Indicates the frequency of the signal to be delayed. Indicates the required delay time. This indicates the phase corresponding to the delay. Therefore, (3) For example, when the input frequency is 5GHz and a phase delay is desired... From the above formula, we can obtain t = 100ps, meaning that setting the delay time to 100ps on the PC will achieve the desired effect. If the delay time remains constant, adjusting the frequency of the input signal will also change the phase. For example, changing a 5GHz signal to 40GHz while keeping the delay time at 100ps will cause a phase shift. The delay is a lag of four complete cycles. Based on the relationship between the corresponding delay time, frequency, and delay phase, the required optical delay time for a 180° delay phase can be obtained for radar signals in each band, along with the relationship between the signal phase shift accuracy that the optical module can control under each band condition, as shown in Table 1 below: Table 1

[0073] Table 2 Advantages

[0074] As shown in Table 2, the phase accuracy of the optical delay module (0.05 ps) is significantly better than that of traditional electrical phase shifters (such as digital phase shifters with a 5° step size), especially in high-frequency bands (such as 40 GHz), where it still maintains sub-degree accuracy. Traditional electrical phase shifters, however, suffer from decreased accuracy with increasing frequency due to device nonlinearity and temperature drift. In cross-eye interference, the optical delay module supports the full bandwidth of 1-40 GHz, while electrical phase shifters (such as ferrite and MEMS) typically only cover specific frequency bands. The optical delay module has a picosecond response speed, far faster than electrical phase shifters (microsecond level), making it suitable for high-speed dynamic scenarios. Regarding interference resistance, optical signals are transmitted in optical fibers and are unaffected by electromagnetic interference, while electrical phase shifters are susceptible to environmental noise. Therefore, the optical delay module can produce high-precision, controllable phase shifts, thus more effectively improving the performance against cross-eye interference.

[0075] Combining the formula for the effective interference gain of radar cross-eye jamming with the relevant data in Table 2, the interference effects of optical delay modules and electronic phase shifters can be compared. Optical delay modules have 10 to 100 times higher accuracy, 10 times higher interference gain, larger bandwidth, support for high-frequency radar countermeasures, stronger anti-electromagnetic interference capabilities, and faster response speeds compared to digital phase shifters. If we assume the radar operates in the X-band (10 GHz), the interference effects under different phase errors can be compared: For this embodiment ( Φ=0.72°), b=1, substituting these values ​​into the effective interference gain formula yields G. 干扰 ≈159, indicating that high interference gain is still maintained. And the traditional phase shifter ( Substituting Φ=5°, we get G. 干扰 ≈22.9, at which point the interference effect decreases significantly. The effects of phase deviation and amplitude deviation on interference gain are shown in Table 3.

[0076] Table 3. Impact of Phase Deviation and Amplitude Deviation on Interference Gain

[0077] The key function of the optical delay line in this embodiment is to precisely adjust the phase of the interference signal. Due to factors such as the relative motion between the interference source and the radar, and changes in platform attitude, the phase of the interference signal is prone to fluctuation. The optical delay line can compensate for the phase difference by precisely controlling the delay time of the optical signal based on the phase changes monitored in real time, ensuring that the phase difference between the two interference signals arriving at the radar is stable at around 180°, thereby enhancing the interference effect and avoiding interference failure due to phase mismatch.

[0078] In different cross-eye interference scenarios, the propagation path of the interfering signal and the interference requirements vary greatly. Optical delay lines need to be highly adaptable, able to flexibly adjust the delay amount according to the signal propagation characteristics and interference requirements of specific scenarios.

[0079] Inserting optical delay lines at appropriate locations in the signal transmission link of a jammer allows for precise adjustment of signal propagation time. For signals with long propagation paths, appropriate delay via optical delay lines ensures that the path difference between the two jamming signals reaching the radar antenna meets jamming requirements, maintaining a stable phase difference of approximately 180° and enhancing the jamming effect. (High phase shift accuracy) This embodiment generates a waveform with a relatively large bandwidth. A large bandwidth results in higher radar accuracy, making the cross-eye interference effect of monopulse radar more significant and achieving better angle deception. (Large bandwidth, high precision) Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0080] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the defined protection scope of the present invention.

Claims

1. A high-precision cross-eye interference system based on optical delay, characterized in that, It includes a receiving antenna, a first transmitting antenna, a second transmitting antenna, a low-noise amplifier, a controllable attenuator, a power divider, an E / O electro-optical conversion module, a controllable optical delay module, and an O / E optoelectronic conversion module; The receiving antenna receives the transmitted signal from the monopulse radar; the transmitting end of the receiving antenna is connected to the input end of a low-noise amplifier, the output end of the low-noise amplifier is connected to the input end of a controllable attenuator, and the output end of the controllable attenuator is connected to the input end of a power divider. The first output terminal of the power divider is connected to the receiving terminal of the first transmitting antenna; the second output terminal of the power divider is connected to the input terminal of the E / O electro-optic conversion module, the output terminal of the E / O electro-optic conversion module is connected to the input terminal of the controllable optical delay module, the output terminal of the controllable optical delay module is connected to the input terminal of the O / E opto-optic conversion module, and the output terminal of the O / E opto-optic conversion module is connected to the receiving terminal of the second transmitting antenna. The transmitting terminals of the first and second transmitting antennas transmit two signals with equal amplitude and opposite phase.

2. The high-precision cross-eye interference system based on optical delay according to claim 1, characterized in that, The power divider splits the received signal into two output signals. One output signal goes directly to the receiving end of the first transmitting antenna with a delay of 0. The other output signal goes through an electro-optical conversion module, a controllable optical delay module, and a photoelectric conversion module, with a delay of 180°, to the receiving end of the second transmitting antenna.

3. The high-precision cross-eye interference system based on optical delay according to claim 1, characterized in that, The bandwidth of the power divider is 1GHz-40GHz.

4. A high-precision cross-eye interference system based on optical delay according to claim 1, characterized in that, The bandwidth of both the E / O optoelectronic conversion module and the O / E optoelectronic conversion module is 1GHz-40GHz.

5. A high-precision cross-eye interference system based on optical delay according to claim 1, characterized in that, The bandwidth of the low-noise amplifier is 1GHz-40GHz.

6. A high-precision cross-eye interference system based on optical delay according to claim 1, characterized in that, The bandwidth of the controllable attenuation is 1GHz-40GHz.

7. A high-precision cross-eye interference system based on optical delay according to claim 1, characterized in that, The combined gain of the low-noise amplifier and the controllable attenuator is adjustable from 1dB to 120dB.

8. A high-precision cross-eye interference system based on optical delay according to claim 1, characterized in that, The controllable optical delay module accepts input signals from 1GHz to 40GHz. The maximum delay of the controllable optical delay module is 1500ps, and the maximum delay accuracy is 0.05ps. The delay time of the controllable optical delay module is obtained using the following formula: in, Indicates the delay time. Indicates the frequency of the signal to be delayed. This indicates the phase corresponding to the delay.

9. A method for operating a high-precision cross-eye interference system based on optical delay, characterized in that, The high-precision cross-eye interference system based on optical delay as described in any one of claims 1-8 includes the following steps: After receiving the signal from the monopulse radar, the receiving antenna reduces the noise figure through a low-noise amplifier. The amplitude of the signal is controlled by a controllable attenuator, and the amplitude-controlled signal is divided into two output signals by a power divider. One output signal arrives at the receiving end of the first transmitting antenna with a delay of 0, while the other output signal arrives at the receiving end of the second transmitting antenna after a delay of 180° through an E / O electro-optical conversion module, a controllable optical delay module, and an O / E photoelectric conversion module. The first and second transmitting antennas then transmit two signals with equal amplitude and opposite phase.

10. A method for interfering with monopulse radar angle measurement, characterized in that, The high-precision cross-eye interference system based on optical delay as described in any one of claims 1-8 includes the following steps: After receiving the angle measurement signal transmitted by the monopulse radar, the system processes the angle measurement signal and transmits two signals with equal amplitude and opposite phase. After receiving the two transmitted signals with equal amplitude and opposite phase, the monopulse radar uses the sum and difference signals to compare the angle measurement method to generate an angle measurement error, thus interfering with the angle measurement of the monopulse radar.

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