Cross-eye Jamming Research Articles

A Cross-Eye Jamming Scheme Based on Microwave Photonics and Its Hardware-in-Loop Performance Investigation

A Cross-Eye Jamming Scheme Based on Microwave Photonics and Its Hardware-in-Loop Performance Investigation

The impacts of phase noise on a long-baseline cross-eye jammer

Cross-eye jamming is a technique used for deceiving the angle measurement of monopulse radars. Long baseline (i.e., long spacing of jammer antennas) is an attractive option for cross-eye jammers, which can increase the angular error for monopulse radars. Phase error is a key factor restricting the performance of cross-eye jammers. In this paper, one of the sources of the phase error, i.e., local oscillator (LO) phase noise, is analyzed for a long-baseline cross-eye jammer. The effect of LO phase noise on the jamming performance is revealed for the first time. Additionally, the tolerance requirements for the LO phase noise of long-baseline cross-eye jammers are determined through theoretical analyses. Finally, the theoretical analyses are verified by Monte Carlo simulations. The research results can provide theoretical insights for system design and component selection for cross-eye jammers.

A Cross-eye Jamming Mitigation Approach for Polarized Monopulse Radars

A Cross-eye Jamming Mitigation Approach for Polarized Monopulse Radars

크로스 아이 재밍을 위한 멀티밴드 다중채널 송수신기의 정밀 가변 위상 및 진폭 매칭 구조 설계

크로스 아이 재밍을 위한 멀티밴드 다중채널 송수신기의 정밀 가변 위상 및 진폭 매칭 구조 설계

Research on Optical Spectrum Processing for Photonic-Assisted Broadband RF Cross- Eye Jamming System

Cross-eye jamming technology has been used in electronic warfare, which attempts to protect a military platform from monopulse tracking radars. The cross-eye jamming technology has the ability of inducing angular errors to the monopulse tracking radars by transmitting two jamming signals with equal amplitudes and opposite phases. At present, high operation frequency and broadband cross-eye jamming system has been rarely demonstrated. Therefore, the present cross-eye jamming systems are hard to jam frequency-agile radar or multi-band radar, whose carrier frequency covers a large spectral range. In this paper, a photonic-assisted broadband radio frequency (RF) cross-eye jamming system is proposed and experimentally demonstrated. To achieve effective jamming effect, the intercepted radar signal is modulated to optical carriers and the phase shift is realized by optical spectrum processing. The relationship between system parameter tolerances and jamming effects are also simulated. Furthermore, the RF transfer function of X-band, Ku-band and K-band has been obtained in the experiments. The experimental results show that the amplitude and phase mismatch are below 2.15 degrees and 0.4 dB, respectively. Calculated cross-eye gain is 39dB.

Probabilistic Analysis of the Amplitude-Phase Error Tolerance for Cross-Eye Jamming

Cross-eye jamming is a technique to counter monopulse radar. The impact of the amplitude-phase error on the jamming performance is one of the key problems for cross-eye jamming. The tolerance of amplitude-phase error for cross-eye jamming has been analyzed by deterministic analysis. However, the amplitude-phase errors of a practical jammer are commonly stochastic variables due to the variation of working conditions. In this article, the probabilistic analysis of the amplitude-phase error tolerance for cross-eye jamming is studied. By demonstrating that the contours of cross-eye gain can be approximate to a set of ellipses, the probability distributions of cross-eye gain and angle factor are derived, based on the assumption that the amplitude-phase errors of cross-eye jammer are Gaussian distributed. The article presents the instructions to determine the required standard deviation of the amplitude-phase error to produce a specific confidence level of cross-eye jamming performance metric.

Analysis of outboard cross‐eye jamming using an unmanned platform

To address the problem and reduce the risk wherein a ship-based cross-eye jammer could set a protected ship as a target, an unmanned platform equipped with a jammer is proposed to be used. However, the jamming situation violates the original cross-eye jamming conditions and introduces some new elements. In this regard, the impact of outboard cross-eye jamming in the presence of ship echoes is derived in detail. The analysis shows that the outboard cross-eye jamming combines the characteristics of outboard active and traditional cross-eye jamming gains. It can reduce the standard cross-eye jamming requirement of the jamming-to-signal ratio (JSR) and improve the jamming effect. The phase difference of a cross-eye jammer can be controlled at 0° or 180° to obtain a larger angular positioning deviation based on the JSR requirement, thus providing a theoretical basis for applications of unmanned outboard cross-eye jamming.

Implementation and Testing of a Retrodirective Cross-Eye Jammer

One of the few electronic attack techniques that can deceive radars in angle is cross-eye jamming, which mimics the naturally-occurring phenomenon glint. The extreme tolerance requirements of cross-eye jamming mean that a retrodirective implementation is required, but published measurements of cross-eye jamming either ignore the retrodirective implementation or only simulate it. The implementation of a retrodirective cross-eye jammer and its testing against a monopulse radar are described. A procedure for calibrating the jammer is outlined and is shown to be effective by achieving large angular errors. The measured results agree well with the extended analysis of cross-eye jamming and confirm that the implemented jammer is retrodirective. Specifically, the ability of a cross-eye jammer to generate an indicated angle that never becomes zero, thereby potentially breaking a tracking lock, is confirmed.

Experimental Approach to Estimate Cross-Eye Gain for a Nonretrodirective Cross-Eye Jamming System

An experimental approach to estimate cross-eye gain for a nonretrodirective cross-eye jamming (NRCJ) system is presented. Cross-eye gain is used as an index to evaluate the cross-eye jamming system. The previous experimental method for obtaining the cross-eye gain using a network analyzer is accurate but requires a complex configuration. In this letter, a method of estimating the cross-eye gain for the NRCJ system by the signal power difference using a spectrum analyzer is proposed. To verify the proposed method, a prototype of the NRCJ system was fabricated. The experimental results showed that the proposed method could estimate the cross-eye gain with a phase-difference error of approximately 2° compared to the simulation.

Performance Analysis of Multi-Group Three-Tuple Cross-Eye Jamming

Monopulse radar is widely used in military. Jamming monopulse radar has always been a research hotspot in electronic warfare (EW). Cross-eye jamming has always been considered as the most effective measures to jam with monopulse radar. In this paper, we propose a multi-group three-tuple cross-eye jamming structure where each group contains three antenna elements with a definite phase and an amplitude relationship. Then, based on the principle of monopulse angle measurement, the error angle is deduced theoretically. Simulations show that such a multi-group three-tuple cross-eye jamming structure performs better than the multi-element cross-eye jamming structure previously proposed, and the analysis of the centroid shows that the centroid of the structure proposed in this paper is more widely distributed in space.

Performance Analysis of Multiple Antennas Synthetic False Target Jamming

The radar jamming technology has been studied in this paper mainly, which uses the antenna synthetic wave to generate phase distortion at the signal reception to carry out angle measuring jamming, such as traditional cross-eye jamming. However, cross-eye jamming has strict parameter tolerance. To improve the tolerance range of the phase parameters, a multiple antennas synthetic false target electromagnetic jamming technique is proposed in this paper, which has a wider phase parameter tolerance and jamming range. The jamming method can be regarded as an improved cross eye jamming method. We can conclude that this method can generate a “false target” in space and far away from the carrier which has jamming system, which mislead the radar to point to “false target” rather than to real targets. A jamming system with three jamming antennas was considered as the research object. The position of “false target” can be controlled casually by adjusting the feed amplitude and phase of the three antennas simultaneously. The jamming mathematical model of synthetic false target with three antenna emitters is constructed under the sum and difference channel transceiver mechanism of radar in this paper. The error angle and synthetic gain of the three jamming antennas were derived. The phase parameter tolerance of the proposed method was obtained- and compared with cross-eye jamming. A rigorous mathematical derivation is proposed in this paper, and the superiority of the multiple antennas synthetic false target jamming method is verified.

Numerical Integration-Based Performance Analysis of Cross-Eye Jamming Algorithm

In this paper, performance analysis of the cross-eye jamming effect under mechanical defects is dealt with. By using a numerical analysis-based approach, the performance analysis method proposed in this paper is closer to the not approximated empirical mean square difference (MSD) than the first-order Taylor approximation-based performance analysis method and the second-order Taylor approximation-based performance analysis method proposed in previous studies. In other words, the effects of amplitude ratio perturbation and phase difference perturbation on performance degradation are quantitatively analyzed. Note that the numerical integration is adopted to derive an analytic expression of the MSD.

Performance Degradation in Cross-Eye Jamming Due to Amplitude/Phase Instability between Jammer Antennas.

Cross-eye gain in cross-eye jamming systems is highly dependent on amplitude ratio and the phase difference between jammer antennas. It is well known that cross-eye jamming is most effective for the amplitude ratio of unity and phase difference of 180 degrees. It is assumed that the instabilities in the amplitude ratio and phase difference can be modeled as zero-mean Gaussian random variables. In this paper, we not only quantitatively analyze the effect of amplitude ratio instability and phase difference instability on performance degradation in terms of reduction in cross-eye gain but also proceed with analytical performance analysis based on the first order and second-order Taylor expansion.

Tolerance analysis of multiple-element linear retrodirective cross-eye jamming

Tolerance sensitivity limits the practical application of the cross-eye jammer. Previous literature has demonstrated that retrodirective cross-eye jamming with multiple antenna elements possesses the advantage of loose tolerance requirements compared to traditional cross-eye jamming. However, the previous analysis was limited, because there are still some factors affecting the parameter tolerance of the multiple-element retrodirective cross-eye jamming (MRCJ) system and they have not been investigated completely, such as the loop difference, the baseline ratio and the jammer-to-signal ratio. This paper performs a comprehensive tolerance analysis of the MRCJ system with a nonuniform-spacing linear array. Simulation results demonstrate the tolerance effects of the above influence factors and give reasonable advice for easing tolerance sensitivity.

Method of Four-Element Retrodirective Cross-Eye Jamming Based on DoA

The cross-eye method is commonly used to interfere monopulse radars. To overcome the strict tolerance and the range limitation of the traditional retrodirective cross-eye method and the multi-loop method, a novel four-element retrodirective cross-eye based on Direction of Arrival (DoA) is proposed. The mathematical model of the four-element retrodirective cross-eye jamming is derived based on the method of expansibility analysis, and the general formulas of indication angle are obtained. Based on the DoA information, the antenna layout of jamming loops is optimized, and the influence of the modulation parameters on cross-eye jamming effect are analyzed. The orthogonal four-element retrodirective cross-eye is compared with the traditional cross eye jamming, the results show that the the proposed method is superior to the traditional and the orthogonal four-element retrodirective cross-eye in terms of the jamming effect and the modulation parameter tolerance.

Analysis of the Monopulse Radar Tracking Errors using Orthogonally Deployed Antenna Sets for Cross-eye Jamming

Analysis of the Monopulse Radar Tracking Errors using Orthogonally Deployed Antenna Sets for Cross-eye Jamming

Statistical Skin-Return Results for Retrodirective Cross-Eye Jamming

The effect of the radar skin return from the platform on which a cross-eye jammer is mounted is significant in many practical cross-eye jamming scenarios. However, all published analyses of skin-return affected cross-eye jamming have significant limitations. These limitations are addressed by deriving equations for the distribution of the cross-eye gain in the presence of skin return. The values of these results are demonstrated by using them to gain insight into how skin return affects cross-eye jamming.

Continuous and Stable Cross-Eye Jamming via a Circular Retrodirective Array

Cross-eye jamming is an angular deception jamming technique against monopulse radar. Multiple-element retrodirective cross-eye jamming (MRCJ) as an improved method, uses a retrodirective antenna array with multiple antenna elements in a cross-eye jammer and can obtain better jamming performance. However, the practical MRCJ system employing a linear antenna array becomes ineffective when the threat radar appears in the antenna array’s end-fire direction. To meet multiple threats from different directions and provide continuous jamming, MRCJ employing a circular antenna array (C-MRCJ) is proposed after defining the modulation direction of system parameters. Optimal configuration of C-MRCJ providing stable jamming performance is discussed. The number of the jammer loops is analyzed under considerable jamming performance and moderate hardware cost.

A novel algorithm to counter cross-eye jamming based on a multi-target model

Cross-eye jamming is an electronic attack technique that induces an angular error in the monopulse radar by artificially creating a false target and deceiving the radar into detecting and tracking it. Presently, there is no effective anti-jamming method to counteract cross-eye jamming. In our study, through detailed analysis of the jamming mechanism, a multi-target model for a cross-eye jamming scenario is established within a random finite set framework. A novel anti-jamming method based on multi-target tracking using probability hypothesis density filters is subsequently developed by combining the characteristic differences between target and jamming with the releasing process of jamming. The characteristic differences between target and jamming and the releasing process of jamming are used to optimize particle partitioning. Particle identity labels that represent the properties of target and jamming are introduced into the detection and tracking processes. The release of cross-eye jamming is detected by estimating the number of targets in the beam, and the distinction between true targets and false jamming is realized through correlation and transmission between labels and estimated states. Thus, accurate tracking of the true targets is achieved under severe jamming conditions. Simulation results showed that the proposed method achieves a minimum delay in detection of cross-eye jamming and an accurate estimation of the target state.

Research on Multi-loop Cross-eye Jamming Optimization Based on Wavefront Phase Distortion

The strict implementation conditions of cross-eye jamming can be effective improved by multi-loop cross-eye jamming, so it has become a stirring research topic. In this paper, the characteristics of wave-front phase distortion in multi-loop cross-eye jamming system are investigated by using two indexes, the degree of center distortion(DCD) and the effective distortion region(EDR). Firstly, the synthetic field model of multi-element jamming signal is derived, and the constraint model is established by taking DCD and EDR as objective functions. Secondly, the parameters such as amplitude ratio, phase difference and the number of loops are optimized by MOEA/D algorithm. Finally, the jamming effect of radar tracking angle is verified by simulation. The results show that, compared with the single loop jamming system, multi-loop cross-eye jamming system can effectively improve DCD and EDR. It is also found that when the number of loops exceeds4, the phase distortion of the jamming signal decreases obviously, which makes the jamming system more likely to act as a radar indicator.