Trends in Electronic Warfare

Since cognition has become an important topic in Electronic Warfare (EW) systems, Electronic Support Measures (ESM) are used to monitor, intercept and analyse radar signals. Low Probability of Intercept (LPI) radars is preferred to be able to detect targets without being detected by ES systems. Because of their properties as low power, variable frequency, wide bandwidth, LPI Radar waveforms are difficult to intercept with ESM systems. In addition to intercepting, the determination of the waveform types used by the LPI Radars is also very important for applying counter-measures against these radars. In this study, a solution for the LPI Radar waveform recognition is proposed. The solution is based on the training of Support Vector Machine (SVM) after applying Principal Component Analysis (PCA) to the data obtained by Time-Frequency Images (TFI). TFIs are generated using Choi-Williams Distribution. High energy regions on these images are cropped automatically and then resized to obtain uniform data set. To obtain the best result in SVM, the SVM Hyper-Parameters are also optimized. Results are obtained by using one-against-all and one-against-one methods. Better classification performance than those given in the literature have been obtained especially for lower Signal to Noise Ratio (SNR) values. The cross-validated results obtained are compared with the best results in the literature.

An improved method of reducing the input impedance of a four-arm sinuous antenna is demonstrated for a wide gain bandwidth. The proposed antenna has a dual-linear polarized response for electronic support measures (ESM) systems and is designed with a planar substrate. The structure for reducing the input impedance is developed based on the transmission and coupled line theory and is shown to be in excellent agreement with theoretical predictions. The proposed antenna achieves an impedance bandwidth in the range of 0.45–6 GHz with a reference impedance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100 ~\Omega $ </tex-math></inline-formula> . Simulations for comparison according to the difference in input impedance of designed antennas with feeding structures are also presented. Finally, the performance of the fabricated antenna with wideband balun is verified by measuring co- and cross-polarization radiation patterns. As a result, the proposed antenna achieves a wide gain bandwidth (>2.5 dBi) and a cross-polarization isolation (>−13 dB) of more than 12:1 in the frequency range over 0.6 GHz, which can be used in ESM systems.

While designing special-purpose radio communication systems, it is important to take into account the work of potential adversaries or intruders who have electronic warfare and electronic countermeasure, whose task is to disrupt radio communications or intercept transmitted messages. Today, a number of methods are known to counteract electronic warfare, the main of them are aimed to avoid destructive influences of radio warfare. In this area, the issue of creating “uncompromising” radio transmitting devices is promising. The term “incompromising” means that a radio transmitting device is capable of transmitting a covert signal in such a way that the enemy's electronic warfare equipment could not fixate the broadcast. The secrecy of the signal is ensured by a set of technical and organizational measures. When studying secrecy issues, the greatest attention is paid to energy secrecy, since this component mainly depends on design decisions at the design stage. The article deals with the problem of obtaining an estimate of the influence of AWGN on the probability of correct signal transmission. The influence of noise and interference is considered as an important element of electronic warfare and countering enemy electronic warfare. The purpose of the article is to study the effect of noise on the degree of energy secrecy of signals. The influence of AWGN and phase noise for BPSK, QPSK, QAM-16 and chirp signals has been evaluated. Based on the results, some regularities are described that make it possible to evaluate the effect of AWGN and phase noise on the noise immunity of these signals. Studies of the chirp signal on the degree of energy secrecy under the influence of noise have been carried out. As a result of the study, conclusions were drawn about the influence of external noise on the degree of energy secrecy of signals, the chirp signal was recognized as potentially suitable for use in special communication systems.

Planning for the deployment of air defence (AD) assets in areas of operation to achieve maximum protection coverage against enemy air threats is an important problem in military science. A three-stage approach to address the problem is proposed: a static methodology to deploy AD resources to maximize the coverage and performance of radar systems under various terrain conditions is studied, followed by the second stage that considers the dynamics of enemy air attacks and Electronic Warfare (EW) conflict that ensues between the attacker and defender modeled using game theory. In the final stage the conflict scenarios modelled using game theory are represented as AD wargames and experimented on a battlefield simulation test-bed called Air Warfare Simulation System (AWSS) to assess the AD effectiveness in operations. The first stage uses a coverage-based optimization, and the second stage is modelled using game theory. The strategies of the attacker (enemy aircraft) and defender (sensors-radars grid and weapons-missiles grid) in the EW operations as Electronic Counter Measures and Electronic Counter-Counter Measures in a game-theoretic setting are illustrated using several scenarios.

A POMDP approach for scheduling the usage of airborne electronic countermeasures in air operations

This paper investigates integrated waveform design for radar systems to simultaneously achieve a low probability of intercept (LPI) by an adversary electronic support measure (ESM) system while maintaining communications with other radar nodes. A reconfigurable intelligent surface (RIS) is exploited and jointly designed to enhance the achievable performance of the whole system. LPI detection based on the ESM’s feature analysis on the radar waveform is achieved under the constraints of a desired signal-to-interference-and-noise ratio for the radar detection and a desired signal-to-noise ratio-based quality of service for the communication channels. To deal with the resulting non-convex optimization problem, a suboptimal composite algorithm with polynomial complexity is proposed. The initial feasible solution of the algorithm is efficiently obtained through an asymptotic optimization problem. Finally, the complexity of the proposed algorithm is analyzed. Simulation results including comparisons with baselines highlight the effectiveness of the proposed scheme.

Although development of electronic warfare (EW) receivers has begun to address the need to detect millimeter wave radars, very little ESM (electronic support measures) performance data have been provided to the system engineering community. This has partially been a result of the sensitivity of some millimeter wave applications. This paper provides a sample of direction-finding (DF) measurements derived from tests carried out on an advanced development model (ADM) millimeter wave (28-40 GHz) ESM receiver using an outdoor test range. DF accuracies of 5-6/spl deg/ r.m.s. are demonstrated as being readily attainable at Ka-band using conventional amplitude comparison monopulse techniques combined with high probability-of-intercept and large instantaneous dynamic range.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The paper refers to the management of electronic warfare systems and the latest approaches in this field. Also, some important main historical milestones and new development trends in the field of EW (Electronic Warfare) are being discussed. Finally, after identifying the relationship between ECM (electronic counter measures) and ES (electronic support) and the gaps in the current research of electronic warfare systems, it has been shown how is this domain influenced in the current context of multiple turbulences and crises

Electronic support measures (ESM) systems use different methods for direction finding (DF). Performance of a DF antenna array is an essential measure of the overall ESM system. A common DF method of phase interferometry using a circular interferometer is discussed. Typically a circular interferometer employs a polarizer to match the desired incident polarizations to the polarization of the antenna array. This paper describes a simulation method for evaluation of polarizer impact on direction finding performance of a circular interferometer. Simulation of DF antenna performance of a circular interferometer with and without a polarizer, using method-of-moments antenna simulation and spreadsheet based post-processing. The benefits of simulation include being a cost effective way of performance prediction for a new design or for the influence of installation structures on an existing system. Sample DF accuracy results are discussed and compared to previously published specifications. This work is based on analysis conducted on the ESM system for the surface combatant force guided missile frigates (FFG ) upgrade project.

Wideband directional couplers are among the microwave components extensively used in electronic warfare, electronic countermeasures, and instrumentation. In this paper, a simple straight line coupling function is used to design a high-pass directional coupler. The ripple performance of a coupler using the linear coupling function is shown to be superior to couplers designed using the cosine type coupling function as reported in (5). In addition, the straight line coupling function is easier to visualize and implement in the design of directional couplers. Other coupling functions such as the Cos type (6) coupling variation provide further reductions in ripple level, but with added mathematical and process complexities.

A 1.3 GHz dual stage i.c. for logarithmic successive detection (s.d.) amplifiers is described. A complete amplifier using three i.c.' s achieves a signal compression accuracy of ± 1dB over an input dynamic range of 65dB at a frequency of 450MHz. This device is aimed at electronic support measures (e.s.m.) systems and is also applicable to high performance signal regenerators such as those used in fibre optic data links.

The field of circular (or cylindrical) arrays has received far less attention than that devoted to linear and planar arrays. At first sight this seems surprising since one of their principal advantages is the ability to deflect beams electronically through 360° with little change of either beamwidth or sidelobe level. Circular arrays have been applied, to a limited extent, in both communication systems and navigational aids since the late 1930s. There has, however, been surprisingly little change in their scale of application since that date, though there are now signs of a significant increase of interest in such arrays for applications to DF (Direction Finding) and ESM (Electronic Support Measures) systems. The analysis and general understanding of the properties of circular arrays has progressed steadily for many years and the most significant developments were probably made by several groups of workers in the 1960s when the concept of phase mode excitation was developed. The lack of applications in the past is prob ably due to the fact that the basic problems of exciting circular arrays with the correct values of amplitude and phase are, in general, more complex than for linear arrays. Furthermore, electronic scanning of directional patterns for circular arrays may be difficult to implement and can require both the amplitude and phase of each element of the array to be changed.

Five basic actions are involved in the sequence of events taken to protect a `platform' (airplane, ship, or tank): pre-engagement collection of intelligence, also known as electronic warfare support measures; self-concealment; threat detection; processing of threat information; and response. The area of electrooptic warfare is used to illustrate these actions.

Detection of the changes in Multi-Functional Radar (MFR) work modes is a critical situation assessment task for Electronic Support Measure (ESM) systems. There are two major challenges that must be addressed: (i) The received radar pulse stream may contain multiple work mode segments of unknown number and duration, which makes the Change Point Detection (CPD) difficult. (ii) Modern MFRs can produce a variety of parameter-level (fine-grained) work modes with complex and flexible patterns, which are challenging to detect through traditional statistical methods and basic learning models. To address the challenges, a deep learning framework is proposed for fine-grained work mode CPD in this paper. First, the fine-grained MFR work mode model is established. Then, a multi-head attention-based bi-directional long short-term memory network is introduced to abstract high-order relationships between successive pulses. Finally, temporal features are adopted to predict the probability of each pulse being a change point. The framework further improves the label configuration and the loss function of training to mitigate the label sparsity problem effectively. The simulation results showed that compared with existing methods, the proposed framework effectively improves the CPD performance at parameter-level. Moreover, the F1-score was increased by 4.15% under hybrid non-ideal conditions.

In radar electronic warfare (EW) reconnaissance, radio frequency (RF) is an important parameter for describing the received pulse, and it is usually used in sorting and identifying radar signals. In order to achieve different detection purposes, different modulations are used in intra-pulse and interpulse radar signals. It is an important frequency modulation mode in radar signals for interpulse frequency modulation, which describes the characteristics of dynamic changes of radar pulse signals. However, it is difficult to describe these characteristics effectively by only using Pulse Description Word(PDW). In this letter, a novel feature, based on symbolization and entropy, is proposed to characterize interpulse frequency modulation characteristics of radar signals. Simulation results show that the proposed feature not only have an excellent performance of describing interpulse RF modulation radar signals, but is also insensitive to the environment with a certain rate of pulses missing and spurious pulses. Besides, in terms of time complexity, it also has a satisfactory performance.