Electronic Countermeasure Systems Research Articles

Microstructure‐Tuned Amorphous Co2FeGe Nanoflakes for Enhanced Microwave Absorption Via Mechanical Alloying

Herein, a simple strategy for fabricating amorphous Co2FeGe nanoflakes by tuning the milling time with mechanical alloying method to enhance the microwave absorption capabilities is presented. These alloys exhibit soft magnetic properties characterized by high saturation magnetization and low coercivity. The enhancement of polarization and resonance effects, leading to improved magnetic and dielectric loss, is attributed to the refinement of crystalline size and the substantial aspect ratio of flaky particles. The minimum reflection loss reaches −48.6 dB at 4.92 GHz with an effective absorption bandwidth of 2.88 GHz in the C‐band. Due to its high Curie temperature, Co2FeGe exhibits considerable potential for maintaining highly efficient microwave absorption capabilities under high‐temperature conditions, thereby providing a novel perspective and technical means for the development of new high‐temperature‐resistant, high‐performance microwave‐absorbing materials. This is expected to play a significant role in future high‐temperature electronic countermeasure systems.

Photonics-based wideband multi-format tunable radar jamming signal generator

A photonics-based radar jamming signal generator is proposed in this paper. By adjusting a polarization controller, interrupted-sampling repeater jamming (ISRJ), comb spectrum modulation jamming (CSMJ), ISRJ and CSMJ composite jamming can be respectively generated after photoelectric conversion. We have experimentally verified the generation of ISRJ signals with duty cycles of 50% and 25%, the generation of CSMJ signals with comb spectrum frequency intervals of 5 MHz and 10 MHz, and the generation of their composite jamming signals in the Ku band. Additionally, the ISRJ and CSMJ composite jamming effect of radar signals in the Ka band has been tested. After matched filtering processing, multiple false targets are produced and the total number of jamming targets can be up to 25, demonstrating significant jamming effects. The proposed structure can generate multi-format jamming signals without using digital radio frequency memory, which is suitable for producing high-frequency and large-bandwidth jamming signals. It can be applied in electronic countermeasure systems.

Protection Against Simulating Interference Based on Coherent Storage and Pulsed Probing Signal with a Random Initial Phase

The confrontation between radar stations and radio electronic countermeasure systems leads to constant advancements on both sides as electronics continue to develop. This multifaceted confrontation determines the success of each side primarily based on the comprehensiveness of analysis and the correctness of the adopted system decisions. Occasionally, decisions are made in pursuit of quality, resulting in success in one aspect but failure in another. One such example is the transition to building radar stations based on true coherence principles. This work highlights the issue of protecting radar stations with true coherence from simulative interference. A method is presented for protecting against “near” simulative interference, which is the most dangerous and is generated between the radar stations and an aerial vehicle equipped with a radio electronic countermeasure systems. The method is based on combining an impulse probing signal with a random initial phase and coherent inter-period accumulation of the received signal.

Two-Dimensional Transceiver Beamforming for Mainlobe Jamming Suppression with FDA-MIMO Radar

With the rapid development of electronic warfare technology, the airborne electronic counter measures (ECM) system can generate mainlobe jamming using range gate pull-off (RGPO) strategy, which brings serious performance degradation of target tracking for the tracking and guidance radar. In this study, a two-dimensional transceiver beamforming approach is proposed to suppress the mainlobe jamming with frequency diverse array using multiple-input multiple-output (FDA-MIMO) radar. The mainlobe jamming signal differs from the real target echo in the joint transmit and receive domain due to the range dependence of FDA beampattern. The amplitude of RGPO signal is greater than the amplitude of real target echo. Thus, the transceiver beampattern can be designed to null out the jamming while maintaining the real target. The jamming suppression performance is studied in consideration of practical range constraint of RGPO. Simulation results are provided to verify the effectiveness of the proposed approach.

Bandwidth superposition of linearly chirped microwave waveforms based on a Fourier domain mode-locked optoelectronic oscillator

Optoelectronic oscillators (OEOs) are promising for radar, communication and electronic countermeasure systems. Among them, frequency-scanning OEOs with wide instantaneous bandwidth are needed for many advanced applications. In this work, we demonstrate a novel system to generate bandwidth-doubled linearly chirped microwave waveforms (LCMWs) based on bandwidth superposition using a Fourier domain mode-locked OEO (FDML OEO). In the proposed system, bandwidth-doubling is achieved by re-modulating the generated LCMW of the FDML OEO onto a frequency-scanning optical carrier signal with the help of an external Mach-Zehnder modulator. LCMWs with wide frequency scanning instantaneous bandwidth of 10 GHz are experimentally obtained. Meanwhile, these LCMWs are tunable in an ultra-wide frequency range from 1 to 39 GHz. Moreover, they are with high frequency sweep linearity of 0.5%. Our work presents a simple method to generate tunable wide-band LCMWs for potential microwave sources.

Photonic-Assisted Microwave Frequency and Phase Shifter for Deception Jamming

A new microwave photonic signal processing structure that has the ability to realise frequency and phase shifting operation is presented. The proposed structure uses Serrodyne phase modulation in a dual-polarisation binary phase shift keying (DP-BPSK) dual-drive Mach Zehnder modulator to shift the frequency of an input microwave signal. This has the advantage over the conventional frequency mixers that the unwanted frequency components adjacent to the frequency translated microwave signal can be largely suppressed. It is suitable for use in deception jamming in electronic countermeasures systems. The phase shifting operation is realised by controlling the bias voltages of the DP-BPSK modulator. The dual-function microwave photonic signal processor has a simple structure and a wide bandwidth. The structure enables commercial modulator bias controllers to be used to provide long-term stable performance. Experimental results are presented that demonstrate a wide operating frequency range of 3 to 16 GHz, an over 35 dB suppression on the spurious signals and 0° to 360° phase shift on the frequency translated microwave signal. Using bias controllers to maintain a large spurious suppression ratio of around 35 dB is also demonstrated.

Constructing the Electronic Countermeasures System Architecture Based on Case-Based Reasoning and Bayesian Inference

In order to promote the quality of electronic countermeasures system architecture, this paper present a methodology for constructing the electronic countermeasures system architecture based on case-based reasoning and Bayesian inference. The methodology described history cases by CPN model, established the largest similarity case and feasibility space by combining the CPN color set and k-means algorithm, and then proposed the optimizing orderings of variables of Bayesian by the LFS (Legal Firing Sequence) of CPN model and maximum information entropy, learned the Bayesian networks structure by K2 algorithm using the result of orderings of variables. At last, this paper concluded the electronic countermeasures system architecture tactics and discussed the way of reasoning for constructing the electronic countermeasures system architecture.

Intelligent ECCM technology via cognition and agility for the airborne radar

The electronic counter countermeasures (ECCM) technology is crucial to the modern airborne radar. In this study, opposed to the intelligent electronic countermeasure system, an intelligent anti-jamming technology is developed, which adjusts the working parameters and ECCM steps in real time and optimises the radar performance in various jamming scenarios. The framework of the proposed intelligent anti-jamming technology includes the cognitive jamming detection and suppression, adaptive frequency agility, and waveform diversity. The application of the proposed technology in the airborne radar is analysed via numerical simulations.

A Rapid Accurate Recognition System for Radar Emitter Signals

Radar signal recognition is an indispensable part of an electronic countermeasure system. In order to solve the problem that the current techniques have, which is a low recognition rate and a slow recognition speed for radar signals, a rapid accurate recognition system is proposed, especially for when multiple signals arrive at the receiver. The proposed system can recognize eight types of radar signals while separating signals: binary phase shift keying (BPSK), linear frequency modulation (LFM), Costas, Frank code, and P1–P4 codes. Regression variational mode decomposition (RVMD) is explored to separate the received signals, which saves time for parameter optimization of variational mode decomposition (VMD). Furthermore, signal separation and a noise removal technique based on VMD and the first component recognition technique based on a deep belief network (DBN) are proposed. In addition, in order to overcome the loss of the secondary component caused by signal separation, a fusion network is explored to increase the recognition rate of the secondary component in a short time. The simulation results show that the recognition system achieves an overall recognition rate of 99.5% and 94% at a signal-to-noise ratio (SNR) of 0 dB when receiving single signals and double signals, while spending 0.8 s and 2.23 s, respectively. The proposed system can also be used to recognize medical and mechanical signals.

Nonlinear theory considering harmonic interaction using Eulerian hydrodynamic analysis

Traveling wave tube amplifiers are one of the most widely used vacuum electronic devices which are employed in various applications, in the areas of such as radar, wireless communication and electronic countermeasures system. Among traveling wave tubes, space-borne helix traveling wave tubes which are of high power, high efficiency, high reliability, long life and radiation hardened, are extensively used in satellite transmitter, data communication system and global positioning system. With the rapid development of the multiphase digital modulation schemes, communication systems are placing greater demands on the output power, electronic efficiency and nonlinear distortion characteristics of space-borne helix traveling wave tubes. However, the nonlinear beam-wave interaction will lead to the generation of harmonics, and thus reduces the output power and electronic efficiency. The harmonics can also act to create beats with the fundamental wave, and thus generate these beat frequencies which are commonly known as intermodulation products. As a result, the bit-error-rate will be increased and the system performance will be compromised. Therefore, the generation of harmonics is of significant current interest in space-borne helix traveling wave tubes. Understanding this effect provides a strong motivation for nonlinear analysis of a helix traveling wave tube. In this paper, a continuous electron phase distribution is obtained by treating the discrete electron beam as a charge fluid based on the Lagrangian theory. Then, to obtain a nonlinear Eulerian theory considering harmonic interaction, the electron phases in Lagrangian theory have been expanded into a series of harmonic components. Considering the 0th component and 1st component of the electron phases only and integrating over the initial phase distribution with the help of the relation of Bessel function, the nonlinear Eulerian theory considering harmonic interaction is established. The nonlinear Eulerian theory considering harmonic interaction is compared to a Lagrangian theory on a set of traveling wave tube parameters which are based on a single section of L-and C-bands traveling wave tubes. It is found that the nonlinear Eulerian theory considering harmonic interaction agrees accords well with the Lagrangian theory before the saturation effect occurs. But, it begins to make a difference near saturation point where the electron overtaking happens. The maximum error in gain between the nonlinear Eulerian theory considering harmonic interaction and the Lagrangian theory is less than 4% at 1 dB gain compression point. So the present nonlinear Eulerian theory considering harmonic interaction can effectively describe harmonic generation at 1 dB gain compression point. The simulation results validate the correctness and effectiveness of our nonlinear Eulerian theory considering harmonic interaction. In futuristic future efforts, it is hoped that the present nonlinear Eulerian theory considering harmonic interaction may provide insights into the behavioral mechanisms of nonlinear effects in space-borne helix traveling wave tubes.

Networking of Tracking Radars of Two Different SAM Weapons to Protect the Missile in Intensive Jamming Environment

<p class="p1">Many countries including India use the Russian made SAM-3 (Pechora) surface-to-air missile (SAM) weapon systems to protect their strategic and tactical infrastructure. The mathematical computations done in this paper, conclusively prove<span class="s1">s </span>that SA-125 low-blow tracking radar of Pechora is vulnerable to jamming. A project was undertaken to overcome the jamming vulnerability of Pechora aiming to design and develop an electronic counter counter measure system. This system networked the Pechora tracking radar with a western tracking radar, Flycatcher, developed by HSA Holland. The latter radar works in a MMW band. When jamming (x band) is employed by enemy aircraft the Low blow radar failed to provide target coordinates. But the flycatcher tracking radar which is tracking in Ka band provided the tracking coordinates (after parallax correction) to the command guidance computer. This way the missile guidance is protected until missile warhead in missile blasts near the target. Extensive trials carried out with a number of aircraft sorties proved the success of this developed system against jamming.</p>

Adaptive detection with conic rejection to suppress deceptive jamming for frequency diverse MIMO radar

With traditional radar systems, it is not easy to classify and suppress the intended false targets, especially in case of the mainlobe deceptive jamming. In this paper, the deceptive jamming suppression issue is formulated as a problem of detecting the presence of target signal while rejecting potential deceptive jamming under the multiple-input multiple-output (MIMO) radar with frequency diverse array (FDA) as the transmit array. The problem at hand is settled by resorting to the generalized likelihood ratio test (GLRT); at the design stage we define the sets where the false target and true target lie in. Since FDA-MIMO radar provides controllable degrees of freedom in both range and angle domains, the sets are range–angle related. This implies that both range and angle properties can be used to suppress the false targets. Based on the detector, a two-pulse scheme is proposed to guarantee high rejection probability of deceptive jamming. At the analysis stage, the performance of the detector is assessed in comparison with the conventional MIMO scenario and other detectors. The performance assessment shows that the proposed solutions are effective in the presence of electronic countermeasure (ECM) systems, especially when facing mainlobe deceptive jamming.

ABORT-Like Detection Strategies to Combat Possible Deceptive ECM Signals in a Network of Radars

We address adaptive detection of coherent signals backscattered by possible point-like targets in presence of thermal noise, clutter, noise-like interferers and, possibly, coherent interferers, i.e., deceptive electronic countermeasure (ECM). To this end, we assume a network of radars: for a given cell under test only a subset of the radars receives ECM signals. Training data containing thermal noise, clutter, and noise-like interferers are available. The problem at hand is solved resorting to the generalized likelihood ratio test (GLRT) and to ad hoc solutions: at the design stage we assume that data collected by the radars can be noise only (namely, thermal noise, clutter, and possible noise-like interferers) plus possible coherent interferers or noise plus coherent useful signal. The performance assessment shows that the proposed solutions are effective in presence of ECM systems.

Predistortion Technology Used for TWTA

According to the predistortion technique of travelling wave tube amplifiers (TWTAs), by analyzing TWTA model proposed by Saleh, the gain transmission function curve and phase expansion function curve of the predistortion circuit are deduced. The linear range of TWTA could be enlarged by using predistortion technique, and invariable gain together with zero phase excursions are reached at the working region of the linearized TWTA. As a kind of microwave and millimeter wave amplifiers, TWTAs find a wide utilization in communication, radar and electronic countermeasure applications. To obtain high output power, TWTAs are usually working at their saturation region where severe nonlinear distortion appears. The nonlinearity manifests gain compression and phase excursion. For digital communications application, the nonlinear distortion increase bit error rate, and this limits system efficiency. For electronic countermeasure applications, the nonlinear distortion limits the output power obtainable at the carrier frequency, and this limits the obtainable efficiency of the system. So insights into measures to improve nonlinearity of TWTAs will benefit wireless communications systems and electronic countermeasure systems. Predistortion technique is one of the best choices [1,2,.

A RELIABILITY MEASURE FOR ESM SYSTEM DEINTERLEAVERS

An Electronic Support Measures (ESM) system consists principally of a passive radar receiver and a deinterleaver. It measures the monopulse parameters of intercepted radars, sorts them into individual radars, identifies those radars, and passes their identities to an Electronic Counter Measures (ECM) system for further action. When the pulse arrival rate is too high for an ESM system, it will skip some pulses and consequently the reliability of radar identification will be decreased. From queueing theory, this paper develops an expression that relates the reliability, quantified as a figure of merit called the factor of successful processing (F,), to the pulse arrival rate and the service times of the ESM system. An on-line method to measure F., is also given, which shows that the measurements are in close agreement with the theoretical values.

Detection Algorithms to Discriminate Between Radar Targets and ECM Signals

We address adaptive detection of coherent signals backscattered by possible point-like targets or originated from electronic countermeasure (ECM) systems in presence of thermal noise, clutter, and possible noise-like interferers. In order to come up with a class of decision schemes capable of discriminating between targets and ECM signals, we resort to generalized likelihood ratio test (GLRT) implementations of a generalized Neyman-Pearson rule (i.e., for multiple hypotheses). The adaptive detectors rely on secondary data, free of signal components, but sharing the statistical characterization of the noise in the cell under test. The performance assessment focuses on an adaptive beamformer orthogonal rejection test (ABORT)-like detector; analytical expressions for the probability of false alarm, the probability of detection of the target, and the probability of blanking the ECM (coherent) signal are given. More remarkably, it guarantees the constant false alarm rate (CFAR) property. The performance assessment shows that it can outperform the adaptive sidelobe blanker (ASB) in presence of ECM systems.

Radar Detection and Classification of Jamming Signals Belonging to a Cone Class

This paper considers the problem of detecting and classifying a radar target signal and a jamming signal produced by a deception electronic counter measure (ECM) system based on a digital radio frequency memory (DRFM) device. The disturbance is modeled as a complex correlated Gaussian process. The jamming is modeled as a signal belonging to a cone whose axis is the true target signal. Two different approaches are analyzed, based on the adaptive coherent estimator (ACE) and on the generalized likelihood ratio test (GLRT), yielding both to a two-block device. The performance of the two detection/classification algorithms are evaluated, analytically, when possible, and by Monte Carlo simulation.

Effect of phase and range gate pull-off delay quantisation on jammer signal

The analysis of jamming signals emitted by electronic countermeasure (ECM) systems after phase quantisation, performed by radio frequency digital memory devices, and after introduction of increasing time delay, is approached. The analysis shows the exact expression of the spectrum of a phase-quantised jamming signal when the quantisation levels are equally spaced. The spectrum of the signal presents a main term that is simply an attenuated version of the signal received by the ECM system, and spurious terms whose amplitude and position depend on the number of quantisation levels. The effect of time delay quantisation introduced by range gate pull-off devices is analytically evaluated, in combination to the phase quantisation. Results show that this second distortion can be generally neglected with respect to the spurious terms because of the phase quantisation, particularly when the number of phase quantisation bits is low.

Ask the user: A practical approach to test program set development

The development of a military weapon system is a long and arduous process. How to maintain that system after it is fielded is often a quick afterthought. The automatic test equipment (ATE) and associated test program sets (TPS) are selected and developed based solely on the physical operating specifications and test parameters of the system. The people who actually use the ATE to repair the system and those who maintain the TPS software usually have little or no input until the ATE and TPS are delivered to them. This paper provides a case study of the development and acceptance of an ATE and TPS for the AN/ALQ-172 electronic countermeasures (ECM) system. It does not dwell on the specific technology and mathematical analyses designed into the TPS, but instead focuses on the end goal - using the TPS to repair the system. The paper discusses the initial development of the TPS without user input, then discusses some of the problems discovered when software maintenance engineers and system repair technicians became involved. The case study concludes with a review of the final TPS acceptance testing and an overview of the benefits and costs of involving the user throughout the development process.

Countermeasures of command and control (C2) capabilities in a hostile environment

For a military airborne platform to survive in a hostile battlefield environment, the rapid detection and geo-location of an enemy (or terrorist) gunner is highly desirable. One approach is to develop an electronic countermeasure system against the gunner's command and communication (C2) capabilities, specifically the usage of modern wireless phones. Such a countermeasure system conducts a quick detection and geo-location of the targeted (hostile) mobile wireless subscriber, allows the airborne platform to make appropriate decisions: 1) to divert and avoid potential military conflicts; 2) to cue artillery supports and prepare for attack; or 3) to relay the coordinates of the potential threat to his own command and control units. In this paper, we discuss the technical approach of the countermeasure system, especially in two design areas: 1) detection and tracking of enemy C2 signals; and 2) geo-location of a targeted communication link.