Radar Seeker Research Articles

Clustering and Cooperative Guidance of Multiple Decoys for Defending a Naval Platform against Salvo Threats

The threat to naval platforms from missile systems is increasing due to recent advancements in radar seeker technology, which have significantly enhanced the accuracy and effectiveness of missile targeting. In scenarios where a naval platform with limited maneuverability faces salvo attacks, the importance of an effective defense strategy becomes crucial to ensuring the protection of the platform. In this study, we present a multi-agent reinforcement learning-based decoy deployment approach that employs six decoys to increase the survival likelihood of a naval platform against salvo missile strikes. Our approach entails separating the decoys into two clusters, each consisting of three decoys. Subsequently, every cluster is allocated to a related missile threat. This is accomplished by training the decoys with the multi-agent deep reinforcement learning algorithm. To compare the proposed approach across different algorithms, we use two distinct algorithms to train the decoys; multi-agent deep deterministic policy gradient (MADDPG) and multi-agent twin-delayed deep deterministic policy gradient (MATD3). Following training, the decoys learn to form groups and establish effective formation configurations within each group to ensure optimal coordination. We assess the proposed decoy deployment strategy using parameters including decoy deployment angle and maximum decoy speed. Our findings indicate that decoys positioned on the same side outperform those positioned on different sides relative to the target platform. In general, MATD3 performs slightly better than MADDPG. Decoys trained with MATD3 succeed in more successful formation configurations than those trained with the MADDPG method, which accounts for this enhancement.

An Identification Method of Corner Reflector Array Based on Mismatched Filter through Changing the Frequency Modulation Slope

The corner reflector is an effective means of interference for radar seekers due to its high jamming intensity, wide frequency band, and combat effectiveness ratio. Properly arranging multiple corner reflectors in an array can form dilution jamming that resembles ships, substantially enhancing the interference effect. This results in a significant decline in the precision attack efficiency of radar seekers. Hence, it is critical to accurately identify corner reflector array. The common recognition methods involve extracting features on the high-resolution range profile (HRRP) and polarization domain. However, the former is constrained by the number of corner reflectors, while the latter is affected by the accuracy of polarization measurement, both of which have limited performance on the identification of corner reflector array. In terms of the evident variations in physical structures, there must be differences in their scattering characteristics. To highlight the differences, this paper proposes a new method based on the concept of mismatched filtering, which involves changing the frequency modulation slope of the chirp signal in the filter. Then, the variance of width and intervals within a specific scope are extracted as features to characterize these differences, and an identification process is designed in combination with the support vector machine. The simulation experiments demonstrate that the proposed method exhibits stable discriminative performance and can effectively combat dilution jamming. Its accuracy rate exceeds 0.86 when the signal-to-noise ratio is greater than 0 dB. Compared to the HRRP methods, the recognition accuracy of the proposed algorithm improves 15% in relation to variations in the quantity of corner reflectors.

Compound weighted fusion evaluation and optimization of intelligent tracking algorithm in radar seeker

This paper designs a hierarchical weighted fusion evaluation/optimization scheme for the radar seeker neural network (NN) tracking algorithm. The first weighted fusion of closed-loop performance index is carried out to exclude the hardware influence on algorithm evaluation. Then, according to different tracking scenarios, the tracking index is divided into different periods; a single period score is given by a linear-nonlinear hybrid scoring mechanism. Furthermore, in a single index, the internal scores of different time periods are weighted and fused for the second time to obtain the index overall score. Finally, the third weighted fusion of the multi-index scores obtains the comprehensive score of the algorithm. We design the parameter evaluation case sets and repeat the aforementioned compound weighting; hence the case with the highest comprehensive score is obtained. Finally, the algorithm is optimized by the highest-score case. The experiment using fuzzy NN radar seeker verifies the effectiveness of the method.

Hierarchical fusion evaluation and optimization of radar intelligent tracking algorithm via hybrid weight design mechanism

In this paper, a hybrid weight design and optimization mechanism is proposed to ensure a better application effect in the multi-level weighted evaluation/optimization process of intelligent neural network (NN) guidance algorithm. According to different target tracking scenarios, the tracking index are divided into different periods, a single period score is given according to a linear-nonlinear hybrid scoring mechanism. Furthermore, in a single index, the internal scores of different time periods are weighted and fused for the second time to obtain the index overall score. Finally, the third weighted fusion of the multi-index scores is used to obtain the comprehensive score of the algorithm. Design the algorithm parameter evaluation case sets, repeat the above compound weighting, obtain the case with the highest comprehensive score. Finally, the algorithm is optimized by the highest score case. In the hybrid weight design mechanism, the objective grey correlation first defines the weight range, then the subjective expert decision method with local extreme expert elimination and standard deviation global test for double optimization finally ensures the weight reliability of the hierarchical evaluation optimization. The evaluation optimization experiment using fuzzy NN radar seeker verifies the effectiveness of the method.

Надувные радиолокационные отражатели: заметность на море

Object and purpose of research. Radar signatures of floating off-board decoys used by foreign navies for eluding anti-ship missiles of at sea are estimated. Materials and methods. Analysis of existing floating radar decoys are based on reviews of leading foreign experts. Signatures of these decoys at sea were calculated using a four-beam model of electromagnetic wave scattering on the underlying surface developed at KSRC. Main results. Quantitative assessments of floating decoy detection ranges by typical anti-ship missile radar seekers are made. Conclusion. The investigations showed that flying radar balloons are more effective in seduction of anti-ship missiles.

Terminal Adaptive Guidance for Autonomous Hypersonic Strike Weapons via Reinforcement Metalearning

An adaptive guidance system suitable for the terminal phase trajectory of a hypersonic strike weapon is optimized using reinforcement meta learning. The guidance system maps observations directly to commanded bank angle, angle of attack, and sideslip angle rates. Importantly, the observations are directly measurable from radar seeker outputs with minimal processing. The optimization framework implements a shaping reward that minimizes the line-of-sight rotation rate, with a terminal reward given if the agent satisfies path constraints and meets terminal accuracy and speed criteria. This paper shows that the guidance system can adapt to off-nominal flight conditions, including perturbation of aerodynamic coefficient parameters, actuator failure scenarios, sensor scale factor errors, and actuator lag, while satisfying heating rate, dynamic pressure, and load path constraints, as well as a minimum impact speed constraint. This paper demonstrates precision strike capability against a maneuvering ground target and the ability to divert to a new target, the latter being important to maximize strike effectiveness for a group of hypersonic strike weapons. Moreover, this paper demonstrates a threat evasion strategy against interceptors with limited midcourse correction capability, where the hypersonic strike weapon implements multiple diverts to alternate targets, with the last divert to the actual target.

In-Flight Radome Slope Estimation for Homing Guidance Using Bearing-Only Measurement via Gaussian Process Regression

The radome refraction problem gives rise to guidance performance deterioration for homing missiles. Aiming to eliminate the effect of radome refraction on the radar seeker, a novel method is proposed for correcting the radome-induced measurement error by using the estimated guidance information. A dynamic model for the estimation system is formulated and the guidance information is estimated online via a multiple-model filtering framework. A Gaussian process regression scheme is introduced to reconstruct the mapping model with respect to the radome error and look angle. Furthermore, an analytical expression for radome slope estimation is derived by calculating the derivative of the surrogate function, represented with Gaussian process models. The contaminated measurement is corrected based on the estimated guidance information and radome slope. Extensive simulation results illustrate that the proposed method is able to estimate the radome slope accurately and improve the guidance accuracy effectively.

An angle error extraction algorithm based on JADE for three-channel radar seeker system with the existence of deception jamming

Mainlobe jamming always causes the degradation of signal detection ability and angle measurement precision of radar seekers. Generally, the target echo and jamming can be separated from each other through blind source separation (BSS)-based methods. However, the angle error information of target cannot be obtained just from the separated sources because of loss of amplitude information. Specially, the angle error information is of great significance for three-channel radar seeker system. Thus, in this paper, based on Joint Approximate Diagonalization of Eigenmatrices (JADE) method, we propose an angle error extraction algorithm for three-channel radar seeker system with the existence of strong deception jamming. Firstly, the model of both target echo and jamming is derived. Secondly, the target echo and jamming are separated from each other through JADE. Then, by the combination of separated target signal with Least Squares algorithm, we reconstruct the target signals of three channels, in which we get the exact specific value of sum-differential channel. Furthermore, the effectiveness of the proposed method is verified by simulations.

Optimal distributed cooperative jamming resource allocation for multi‐missile threat scenario

Jamming resources allocation (JRA) is an essential task in clustered combat environments. Especially in cases with multiple threats, efficient JRA is imperative for protecting key assets. In this study, multiple distributed outboard jammers protecting multiple targets against a multi-missile threat are considered, where the function of JRA includes jamming object selection and jammer power allocation. To address this problem, first, a scheme to evaluate the jamming effectiveness of the radar seeker under cooperative jamming from multiple jammers is proposed. Considering power allocation, a mixed-integer programing model for the optimisation of JRA is further established. A two-track simultaneous update binary particle swarm algorithm (TS-BPSO) is then devised to obtain the solutions of the JRA. Finally, the effectiveness of the proposed method for multiple jammers in the multiple missiles scenario is evaluated through simulations. The simulation results suggest that the distributed cooperative jamming resource allocation is affected by the incoming orientation of the missile and the relative position of the jammers and the targets. The findings of the study enable evaluating the use of jammer formations and provide insights into developing effective jamming strategies.

An Approach to Target Reselection for Anti-Ship Missile Against Centroid Jamming with Accurate Tracking Information

By equaling the detection of centroid jamming to the “outlier” detection in the process of tracking with Kalman filter, an approach to target reselection for anti-ship missile against centroid jamming with accurate tracking information is proposed in this paper considering the mutation of the law of motion at the tracking point under centroid jamming. For this approach, an accurate target tracking model is built on the basis of extended Kalman filter (EKF). Using the information collected by radar seeker including distance, velocity and angle, it could achieve the accurate tracking of the target and determine the motion state of the target accurately. On this basis, the orthogonality of innovation in the process of Kalman filtering is utilized to detect any mutation of the motion state of the target, so that the existence of centroid jamming is detected when there is any mutation of the law of motion at the tracking point in the process of chaff centroid jamming. This offers a new solution for remote beyond-visual-range (BVR) anti-ship missile against centroid jamming.

Research on Test Method of Smart Anti-Towed Radar Active Decoy in Complex Electromagnetic Environment

As an effective jamming method, towed radar active decoy, poses a great threat to monopulse radar seekers, and has attracted more and more attention from various countries. This article analyzes the interference mechanism and main parameters of towed radar active decoys, and provides a theoretical basis for the use of towed decoys. In view of its technical characteristics, combined with technical and tactical countermeasure strategies and technical approaches, research the test range to carry out countermeasures against towed radar active decoys, and provide theoretical basis and reference value for the use of towed radar active decoy countermeasures in the range.

Review on Frequency Agile Radar Seeker

Review on Frequency Agile Radar Seeker

Mono-pulse radar angle estimation algorithm under low signal-to-noise ratio

In the case of low signal-to-noise ratio (SNR), in order to improve the angle measurement accuracy of the mono-pulse radar seeker, a target angle estimation algorithm is proposed. The algorithm takes the target angle as a state variable under the Bayesian framework, expands it to the state vector, performs state modeling and observation modeling on it, and builds a particle-based eye angle estimator, which improves the target angle estimation performance. The effectiveness of the algorithm is verified by the simulation data of the medium pulse repetition frequency radar seeker.

A Dynamic Range Ambiguity Resolution Algorithm for Radar Seeker Based on Vote Accumulation

A Dynamic Range Ambiguity Resolution Algorithm for Radar Seeker Based on Vote Accumulation

Удосконалений спосіб напівактивного самонаведення зенітних керованих ракет з вимірюванням дальності ракета-ціль

У статті розглядаються питання удосконалення способу напівактивного самонаведення зенітних керованих ракет з радіолокаційними головками самонаведення на повітряні цілі. Запропонований спосіб ґрунтується на використанні додаткової інформації про просторове положення цілі та ракети під час самонаведення на повітряну ціль. Як додаткова інформація розглядається відстань між зенітною керованою ракетою та повітряною ціллю у процесі напівактивного самонаведення. Реалізація запропонованого способу передбачає застосування у процесі наведення зенітної керованої ракети комбінації монохроматичних та частотномодульованих сигналів підсвічування. На користь запропонованого способу напівактивного самонаведення свідчать наведені у статті результати оцінки середньоквадратичних помилок вимірювання дальності ракета – повітряна ціль.

Cooperative Loitering Munition Swarm Online Patrolling Route Planning with Nonlinear Seeker Measurement

With the development of autonomous systems, the operational use of loitering munition is shifting from the following of a preplanned fixed route without communication to smart decision-making and collaborative cooperation with sharing information. In this paper, we study the autonomous decision-making and cooperative control strategy of online patrolling for a swarm of loitering munitions using communication to coordinate their route based on maximizing the information they gathered in the operation region. Taking the non-Gaussian nonlinear property of airborne radar seeker into account, we utilized a particle filter-based method to evaluate or to predict the information quality of each action candidate. We also implemented a coordinate descent scheme to enable a distributed and scalable swarm decision-making. Simulation results show that the proposed method provides a better estimation than baselines without the need for external or centralized decision agent.

Determination of Maintenance Time of Radar Seeker Based on ABC Method

According to the health state grade classification standard of seeker and the corresponding performance state description, the health state grade corresponding to the predicted value of performance index parameters of transmitter and antenna servo mechanism is evaluated. As a result, the health status grade of the seeker system is obtained. In order to determine the maintenance time of the seeker more accurately, the comprehensive performance index of the seeker in the stage of “deterioration” is divided by the application of ABC analysis rule. Finally, the best maintenance time of seeker is determined by calculation.

Radar seeker performance evaluation based on information fusion method

Radar seeker is responsible for transmitting the dynamic position information of the target back to the weapon control center in the guidance phase. It is of great engineering significance to evaluate the anti-jamming ability of radar seeker in the anti-jamming environment Aimed at obtaining more reasonable evaluation result, an evaluation method based on information fusion is proposed against the background of angle measurement performance in this paper. Radar seeker performance test have many stages with different characteristics. Information fusion has advantages in radar performance evaluation which takes advantage of measured data obtained in different stages rather than process them respectively. Furthermore, we studied two specific issues in the information-fusion stage. The first problem is about consistency testing between different information using K-L information distance measurement, which is the premise of information fusion. The second problem is about the information weights calculation by PLT criterion, which can take sample size into account. Information fusion can make full use of the multi-source test information to obtain more reliable evaluation conclusion. Experimental results prove the effectiveness of the proposed method.

Research on Ship Target Radar Scatttering Characteric Measurement in Sea Battlefield

Study on electromagnetic scattering related to ship target in the sea battlefield environment is always an important topic in radar seeker detection.。Dynamic measurement of radar cross section (RCS) of surface ship in outfield is an important means to obtain change in surface ship navigating and measurement environment and so on, the fluctuation of RCS is random and irregular. The statistic analysis for measurement RCS data in outfield of a certain ship is very important. In this paper, based on the airborne radar belong to Science and Technology on Electromagnetic Scattering Lab, the method of ship target measurement, It obtains the statistical distribution rule of ship’s RCS fluctuation. Compared the measured data with the numerical results, the similarity measure result shows a good agree. It shows that the measurement method is valid.

Application of AHP and D‐S evidential theory in radar seeker anti‐interference performance evaluation

Application of AHP and D‐S evidential theory in radar seeker anti‐interference performance evaluation