Tolerance Analysis of Cross-Eye Jamming Systems

IEEE Transactions on Antennas and Propagation, 2009

An extended and rigorous analysis of retrodirective cross-eye jamming in a radar system scenario is presented. This analysis removes the approximations that limit the validity of other analyses of cross-eye jamming. These results imply that under certain conditions, a monopulse radar system can be more easily deceived than suggested by conventional cross-eye analyses. Furthermore, the cross-eye jammer antenna patterns do not affect the induced monopulse error.

International Conference on Aerospace Sciences and Aviation Technology, 2001

This paper presents the mathematical analysis of a proposed jamming technique used against IAC monopulse radar. The idea of this technique is to repeat the radar signal with change in its amplitude and phase (deception jamming signal) to produce an angular error in the target tracker. This error changes for different values of amplitude ratio and phase difference w.r.t the target signal. In the generated deceptive jamming signals, the change in the amplitude ratio makes large effect than the change in the phase difference on the real part of the complex measured error angle. The real value of the complex measured angle due to jamming with constant phase difference and different amplitude ratio has large variation at amplitude ratio less than three. This value converges to the value of the angle of the false target for higher amplitude ratio. There is no jamming effect at amplitude ratios less than one and for some values of phase difference. At these values, the measured angle equals to the angle of the real target. At least two jamming signals are required to have the complex error jamming angle to overcome the ECCM techniques that might be used by the target.

2012

Missile borne Monopulse receivers invariably track the target in three domains, namely frequency, range and angle. For effective jamming of these receivers, it is essential that breaking of the track should be achieved in at least two domains. In frequency domain, so long as the monopulse receiver locks onto the radar echo frequency, the radar tracks the target. When there is a disturbance introduced either in form of deliberate noise or repeat jamming, the receiver loses the lock to the target and is misguided. In this paper, the monopulse receiver with third order PLL (Phase Locked Loop) is designed and the performance of the receiver is analyzed when sinusoidal CW (Continuous Wave) radar echo signal along with sinusoidal jammer signal is applied to the receiver. In addition, when FM (Frequency Modulation) CW jammer signal along with the radar echo signal is injected into the receiver, the value of modulation index for which break-lock occurs for different values of modulating signal voltage is estimated and an empirical relation is also obtained. The mathematical model for FM CW radar receiver is developed and implemented using Visual System Simulator. The model includes the generation of radar echo and jammer signal at the receiver input to achieve effective jamming. The effectiveness of noise jamming is also studied by injecting phase noise and White Gaussian noise signal into the receiver and break-lock condition of the receiver is also reported. It is shown that break-lock in the receiver occurs when the FM modulation index (K f) exceeds 4x10 6 without exception with the carrier signal operating at40 MHz and when the modulating signal amplitude is 5 mV.

International Journal of Electronics and Electrical Engineering, 2014

Monopulse radar receivers are the most advanced tracking receivers which often employ phase locked loop (PLL) for coherent detection of the received echo signal to become jam resistance and clutter rejection. In this paper, the loop error in the monopulse receiver is characterized analytically taking several higher order harmonics of input signal phase into account. The effects of these harmonics in breaking the frequency lock in the receiver are studied. The phasor diagram is used as an index to determine input signal phase for the given voltage controlled oscillator (VCO) phase and loop phase error at different values of frequency separation between radar echo signal and interference signal. This allows in computing additional phase error and jammer to radar echo signal amplitude (J/S) ratio required for jamming the receiver. The result shows that for the given phase error, the receiver requires large J/S ratio for break-lock when several higher order harmonics are taken into account. It is also shown that the error results due to higher order harmonics is positive and linear. Thus, the additional J/S ratio required for break-lock can be predicted from the error when fundamental harmonics is considered alone. This reduces the complex computation of J/S ratio required for break-lock when higher order harmonics are considered in the loop analysis. The analysis of the loop taking higher order harmonics into account is carried out for typical loop damping ratio of 0.707 and 1.0.

International Conference on Aerospace Sciences and Aviation Technology

This paper studies the performance of modern guided systems in presence of a proposed deception jamming technique. The proposed jammer uses the intercepted signal of the guided system to deceive the instantaneous amplitude comparison (IAC) monopulse radar, which is used in the most modern guided system. The performance of the modern guided systems in the presence of jamming for a typical case of radar guided missile is discussed for the following guidance methods: proportional navigation, pure pursuit, and constant bearing. It is found that, the guided system that uses pure pursuit guidance method is the most affected by the proposed jamming technique (largest miss tracking distance). Constant bearing guidance method is the lowest method affected by the proposed jamming technique (lowest miss tracking distance). Proportional navigation, that is the most used guidance method, is moderate affected by the proposed jamming technique. This effect is enough to confuse the guided system and miss track the target.

IEEE Antennas and Wireless Propagation Letters, 2017

Motivated by the need to cope with different jamming scenarios in modern electronic warfare, an enhanced processing architecture is proposed for phased array radar by reversing the conventional order of adaptive beamforming and monopulse beamforming. Specifically, each row or column is utilized as the identical subarray for adaption and multiple degrees of freedom are exploited. The full-aperture monopulse beamforming is, then, performed along column and row. Without any prior knowledge, the mainlobe and/or sidelobe jammings can be canceled simultaneously, whereas the angle estimation accuracy is well preserved. Simulation results illustrate the efficiency of this technique with a rectangular array. Additionally, evaluation shows the subarraybased scheme maintains the high performance of both jamming cancelation and angle estimation at a low cost.

International Journal of Electrical and Computer Engineering (IJECE), 2019

In this paper, we determine an optimal range for angle tracking radars (ATRs) based on evaluating the standard deviation of all kinds of errors in a tracking system. In the past, this optimal range has often been computed by the simulation of the total error components; however, we are going to introduce a closed form for this computation which allows us to obtain the optimal range directly. Thus, for this purpose, we firstly solve an optimization problem to achieve the closed form of the optimal range (Ropt.) and then, we compute it by doing a simple simulation. The results show that both theoretical and simulation-based computations are similar to each other. 1. INTRODUCTION There are different kinds of radar systems for different applications in industries, airports, military organs such as navy and so on. A type of radars is the tracking radars which are applied in fire control and etc [1]. Generally, two classes of tracking radars can be considered as angle tracking and range tracking radars. Our aim in this study attends to the first class. Figure 1 shows a real sample of tracking radar which has been placed on a ground platform for the fire control usages. Tracking radar for finding angle can use several tracking modes (scanning techniques) including sequential lobing, conical scan and monopulse (e.g. in terms of amplitude) [1]. These three techniques are different in terms of the error status. So, the mode used in each angle tracking radar must be considered in computing the error and then the optimal range of radar. Figure 2 shows a schematic which explains the mechanism of angle tracking radars. From step 1 to step 6, a target is seen in PPI display which tracked during these steps. Figure 3 and Figure 4 show the block diagram of two types of angle tracking radars based on monopulse and conical scan techniques, respectively [2], [3]. In [1]-[3], it is explained that in terms of angle error, two techniques of sequential lobing and conical scan are similar to each other. In the next parts, we specify the differences between the impacts of monopulse and conical scan/sequential lobing (non-monopulse) techniques. Computing the optimal range of each angle tracking radar is an optimization problem which depicts one of the main parameters of the radar. In [1], this problem has been represented, but it is only solved by simulation and numerical computation. As a completing approach for [1], we wish to solve this problem theoretically. In addition, we obtain the simulation result to compare to the proposed approach. In the appendix of this paper, we give the readers a sample MATLAB code in order to the simulation-based computing of the optimal range.

IEEE Transactions on Aerospace and Electronic Systems, 2001

A radar digital beamforming (DBF) architecture and processing algorithm is described for nulling the signal from a mainlobe electronic jammer and multiple sidelobe electronic jammers while maintaining monopulse angle estimation accuracy on the target. The architecture consists of a sidelobe jamming (SLJ) canceling adaptive array (AA) followed by a mainlobe jamming (MLJ) canceler. A mainlobe maintenance (MLM) technique or constrained adaptation during the sidelobe cancellation process is imposed so that the results of the SLJ cancellation process do not distort the subsequent mainlobe cancellation process. The SLJ signals and the MLJ signals are thus canceled sequentially in separate processes. This technique was developed for improving radar processing in determining the angular location of a target, and specifically for improving the monopulse technique by maintaining the accuracy of the target echo monopulse ratio in the presence of electronic jamming by adaptive suppression of the jamming signals before forming the monopulse sum and difference beams.

International Conference on Radar Systems (Radar 2017), 2017

A 3-D staring radar operates by using a wide beam transmitter to illuminate the entire surveillance region and generates multiple receive beams using a 2-D static array that can be digitised at element level. The sensor achieves permanent search in all directions and harnesses the spatial, temporal and spectral domains to improve detection and discrimination of low observable, highly manoeuvrable targets in congested air space against strong non-stationary clutter. While the susceptibility of traditional scanning radars to jammers has been well researched, very little work has been carried out to assess the performance of 3-D staring radars in the presence of an interference source. In this paper, the response of a staring array radar to a jammer is modelled. Results are presented showing that by exploiting the persistent dwell time of the staring array, it is possible to achieve effective jammer suppression using null steering or similar techniques.

Procedia Computer Science, 2015

Monopulse technique is widely used in modern tracking radars and missile seekers for precise angle (frequency) tracking. In this paper, the break-lock behavior of phase locked loop (PLL) in monopulse radar receiver in presence of linear frequency modulated (LFM) repeater jamming signal is presented. The radar echo and LFM signals are injected into the PLL simultaneously with an assumption that initially, the PLL locks onto the echo signal frequency. The frequency deviation required for breaking the frequency lock as a function of jamming signal power and modulation rate is reported. The results show that break-lock is achieved at frequency deviation of 0.35 MHz for a typical jammer power of-14 dBm and 200 kHz modulation rate when the radar echo power at the PLL input is-14 dBm. The break-lock is also studied for different modulation rate (200, 300, 400 kHz and so) and echo signal power (-14,-10 dBm) at the input of the PLL. For the computer simulation, the radar echo and centre frequency of LFM signals are assumed at an intermediate frequency (IF) of 50 MHz such that the LFM signal closely replicate the actual radar echo signal. The PLL containing charge pump phase detector and passive loop filter is designed with a typical bandwidth of 200 kHz. The simulation is carried out using visual system simulator AWR software and potential conclusions are demonstrated.