Modeling and analyzing interference signal in a complex electromagnetic environment

Electronic jamming is the key technology of electronic warfare, for which models and simulation are studied on noise jamming deception jamming and chaff jamming. In the noise jamming, the simulation analysis of radio frequency noise jamming is conducted and the theoretical models of other forms of noise jamming are built. The simulation analysis of RGPO is carried out in the deception jamming. In addition, theoretical modeling and simulation analysis of chaff jamming are carried out with the Monte Carlo method. Simulation results show that the models are correct and can be used to simulate the statistical characteristics of chaff jamming.

Synthetic aperture radar (SAR) has been involved in military applications such as high resolution imaging, battle field surveillance, and moving target detection. Recently noise and deception jamming signal are introduced to counter SAR sensor, thus these jamming techniques can be used to protect ground targets or objects of high interest. In this paper, a comparative study of the performance of the deceptive and the noise jamming on a SAR focused image, with and without jamming, is performed. Two evaluations craterous, structural similarity index measure (SSIM), and correlation coefficient (CC) are used to measure the previous jamming techniques effect on a real SAR focused image (object of high interest). The computer based simulation results, reveal that for the same CC, the power required by the deceptive jamming is reduced by three order of magnitude compared with the power required by conventional noise jamming, mean while for the same SSIM the required power is reduced by nearly two order of magnitude.

Multichannel synthetic aperture radar (SAR) systems represent a critical advancement in SAR development, yet their effectiveness is increasingly challenged by complex electromagnetic environments. Deceptive jamming, capable of generating false targets, significantly compromises target detection and tracking performance. Conventional blind source separation (BSS) methods fail when jammers exceed system degrees of freedom (DOF), while channel cancellation techniques are ineffective against multiple interference sources. To address these challenges, this paper presents an innovative integrated approach combining jammer localization and suppression. First, jammer directions-of-arrival (DOAs) are estimated via clustering analysis of SAR-imaged data, exploiting the inherent sparsity of deceptive targets to resolve mixing-matrix ambiguity without post-separation identification. Second, a pre-transformation processing method based on sequential quadratic programming (SQP) was implemented to equivalently modify the DOAs distribution of jammers. This innovative approach enables the proposed scheme to effectively handle scenarios with most general distributed jammer directions. Finally, effective jamming suppression is achieved combined with the improved minimum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\ell _{1}$</tex-math></inline-formula>-norm method. Experimental results demonstrate significant performance improvements, including a 21.75 dB enhancement in the target region's peak signal-to-noise ratio (PSNR) and an interference suppression ratio (ISR) reduction to -21.75 dB in distributed target, validating the method's effectiveness in general deceptive jamming scenarios.

Electrical stimulation vs thermal effects in a complex electromagnetic environment

Blanket deception jamming is characteristic of both noise jamming and deception jamming, which cause some traditional anti-jamming measures invalid such as sidelobe canceling and sidelobe blanking and so on. In this work, an approach of time-space cascade adaptive sidelobe canceling based on jamming sample recognition is presented. Even when the number of jammings is more than that of auxiliary channels, the suppression results is still very good. The computer simulations demonstrate the validity.

Modern warfare is carried out in a complex electromagnetic environment, where noise suppression interference directly affects the detection ability of airborne warning radar to target, in order to make airborne warning radar play its due role in battlefield. More and more requirements are put forward for radar combat capability in complex electromagnetic environment, that is, the requirement of radar anti-jamming ability in complex electromagnetic environment is becoming higher and higher. Suppression jamming is to cover or submerge useful signals with noise or similar jamming signals to prevent radar from detecting target signals. In order to evaluate the influence of suppression jamming on airborne warning radar, the influence of suppression jamming on the detection probability and detection distance of warning radar is analyzed. The variation of radar detection range and detection probability in complex electromagnetic environment compared with normal detection is given by flight test. It also provides a reference for evaluating the anti-jamming ability of airborne warning radar after being suppressed.

The battlefield environment that modern electronic information equipment faces during use is very complicated, which has become one of the main characteristics of the informationized battlefield. This article starts with the composition and characteristics of a complex electromagnetic environment, references relevant standards, introduces the definition and composition of a complex electromagnetic environment, and summarizes its characteristics. On this basis, this article introduces the general methods of complex electromagnetic environment tests, including digital simulation tests, semi-physical simulation tests, and full-physical simulation tests. Among them, in the full physical simulation test, an equivalent method is generally used to achieve it. At the same time, this article introduces test evaluation methods, including element-level evaluation and effectiveness-level evaluation. Combining engineering practice, this paper puts forward the difficulties of constructing a complex electromagnetic environment. It is an inevitable requirement for the development of weapons and equipment to carry out comprehensive experimental research on the complex electromagnetic environment of aircraft, and to be able to assess the combat capability of the product. It is also an objective requirement for the development trend of the information military.

This study introduces an electromagnetic interference detection technique to increase the immunity of a microcontroller-based system in a complex electromagnetic environment (EME). The detection method is explained. First, the interference in the power supply and at the input port of the microcontroller is detected. The simulation results are achieved in both time domain and frequency domain. The measurement results are obtained to verify the correctness of the detection method and the application of the detection method in the automotive field is presented. The final objective of the work is to ensure that the microcontroller-based system works fast in a normal EME and correctly in a complex EME without adding too much cost.

This article presents an overview of wideband and multiband antennas for both ground-based and airborne applications. It includes previously published designs as well as new ones with improved performance. The use of such antennas significantly enhances the overall efficiency of communication systems. For airborne antennas, benefits include reduced aerodynamic drag, improved performance of radio communication equipment, lower UAV takeoff weight, reduced feeder line losses, and improved electromagnetic compatibility. For ground antennas, advantages include reduced weight and size of the ground control station (terminal), simplification and higher efficiency of the data terminal, shorter deployment time, and improved mechanical strength. The article also presents an application diagram for wideband and multiband antennas in UAS communication systems. The diagram illustrates the potential of using multiple communication modems configured for different frequency ranges via microstrip multiplexers. The results can be useful for developers of both unmanned aerial systems and UAS communication equipment, including individual components. The article demonstrates that the use of wideband and multiband ground and airborne antennas can substantially improve communication quality in complex electromagnetic environments while maintaining optimal values for weight, size, aerodynamic drag, and technological advancement of UAS communication equipment.

The increasingly complex electromagnetic environment (CEME), characterized by dense signal occupancy, intentional interference, and dynamic spectral congestion, poses significant challenges to electromagnetic (EM) sensing technologies. This review comprehensively surveys the theoretical foundations and practical applications of EM sensing within such challenging environments. Key theoretical principles underpinning robust sensing in CEME are elucidated. The topics include wave propagation fundamentals, advanced modeling and characterization of CEME, detection and estimation theory under interference, and electromagnetic compatibility coupled with dynamic spectrum management. The practical deployment of EM sensing technologies is examined across critical sectors including defense (leveraging cognitive radar, multi-sensor fusion), communications (spectrum sensing for cognitive radio/dynamic access), and aerospace (addressing interference threats like 5G to altimeters). Emerging trends such as AI/ML-enhanced sensing, integrated sensing and communication, and collaborative/distributed sensing networks are highlighted as pivotal for future advancements. The review concludes by outlining key challenges and research directions aimed at enhancing sensor adaptability, resilience, and spectral efficiency in the face of ever-growing EM complexity.

Navigation receivers of global positioning systems that are operated in complex electromagnetic environment must have an increased noise immunity characteristic. One way of such noise immunity rising is to use incoherent operating mode of navigation receiver. There are known processing algorithms for navigation signals with Binary Phase Shift Keying (BPSK) modulation. But in the near-term outlook Global Navigation Satellite Systems (GLONASS), Global Positioning Systems (GPS) and Galileo known navigation signals with Binary Offset Carrier (BOC) modulation will be radiated. Processing algorithms for such signals are not described in scientific literature. So it is interesting to work out processing algorithms for BOC modulated signals in incoherent operating mode of navigation receiver. The article is devoted to synthesis and analysis of incoherent subcarrier tracking system under receiving BOC (1,1) navigation signals. To synthesize an optimal tracking system, optimal estimation theory and dual estimation method are used that allow taking into account multi-peak a posteriori distribution of delay that caused by the periodic process (digital sinusoid) in the radio signal modulation function. When analyzing the synthesized estimation algorithm, the procedure for describing delay discriminators and dual variable discriminators were used in the form of a statistical equivalent, including discrimination and fluctuation characteristics. New equations have been obtained that describe optimal tracking system for incoherent mode of a navigation receiver. New expressions for delay and dual variable discriminators are derived. The article gives a scheme for these discriminators and formulas for their statistical characteristics. Simulated results are provided that illustrate accuracy characteristics enhancement. The obtained tracking algorithms may be used in the navigation consumer equipment of GLONASS, GPS, Galileo and other radio-navigation satellite systems operating with BOC(1.1) modulated signals.

Tracking radar can track targets and calculate distance, angle and speed of targets continuously, stably and accurately. Range gate pull off (RGPO) jamming is an active deception jamming aiming at range tracking radars. As to conventional RGPO jamming, opposite radars can identify the direction of pulling by narrow gate monitoring method, gate speed monitoring method or others, and then adopt corresponding front or trailing tracking. For the conventional RGPO jamming doesn't performs well under the circumstances of anti-jamming conducted by the opposite radar, this paper proposes bidirectional false targets RGPO jamming, and the effectiveness and reliability of this jamming type are verified by simulations. Simulation results show that the performance of bidirectional false targets RGPO jamming is superior to the conventional RGPO jamming, which increases the difficulty of anti-jamming for the opposite radars.

Aiming at the requirements of multi-spectral transparency, electromagnetic (EM) shielding and radar stealth for window materials in visible-infrared (IR) integrated optoelectronic systems, this paper proposes a double-layer indium tin oxide (ITO) micro-nano structure metamaterial based on a ZnS substrate, which realizes the efficient coupling of "dual - spectral transparency - EM shielding - radar stealth". Through the periodic collaborative design of the bottom orthogonal grid network and the upper concentric square ring patches, while ensuring high transmittance in the visible light (380-780 nm) and IR (2-10 μm) bands, the EM shielding efficiency (SE) in the 100 MHz to 1 GHz frequency band is achieved to be more than 20 dB, and the absorption rate in the X-band (8-12 GHz) is more than 90%. Theoretical modeling and simulation reveal the composite action mechanism of "grid equivalent admittance shielding-resonant cavity energy dissipation", and magnetron sputtering and photolithography techniques are adopted to achieve millimeter-scale microstructure fabrication. Experimental results show that this metamaterial breaks through the balance limitations among light transmittance, SE, and radar stealth performance of traditional transparent shielding materials, providing an integrated solution for the protection of optoelectronic systems in complex EM environments.

To solve the problem that tradition signal recognition algorithms cannot effectively recognize the contaminated and diverse radar signals in complex and variable Electronic Warfare (EW) environment, a new recognition method based on deep convolutional neural network (CNN) and time-frequency (TF) analysis is proposed. Firstly, the TF images of radar signals are extracted as the inputs to the CNN model. Then, a new network, called CNN-TF, is constructed to analyze these time-frequency images and use the robustness of CNN to suppress the noise interference. Thirdly, a complete and diverse signal librai7 is constructed based on the complex EW environment, and the librai7 is used to train and test CNN-TF. Finally, trained CNN-TF will be used for signal recognition. Simulation results show that the proposed algorithm not only improves the performance of signal recognition, but also has excellent anti-noise performance, which makes the proposed algorithm adapt to the complex and variable electronic warfare environment.

Radar signal sorting is a key technology in electronic warfare. The quality of signal sorting directly determines the outcome of electronic warfare. The accuracy and real-time performance of signal sorting are two important indicators to evaluate the quality of signal sorting. With the increasingly complex electronic countermeasure environment, there are many radar radiation sources in the battlefield, and the signal aliasing is serious. At the same time, there may be pulse loss and interference pulse in the electromagnetic environment. In such a complex electromagnetic environment, in order to improve the accuracy and real-time of radar signal sorting and master the battlefield initiative, this paper proposes a method of radar signal batch processing sorting based on sliding window. Firstly, the radar signal sorting transient library and the sorted radar signal library are set up, and the transient library is used to store radar signals in the sliding window. Move the sliding window continuously from the starting point. When the number of signals in the transient library is higher than the specified threshold, sort the radar signals in the transient library, and then store the sorted radar signals in the sorted radar signal library and delete them from the transient library. When the sliding window moves to the end point, the signals in the sorted radar signal library are merged. Simulation results show that compared with traditional methods, the proposed method has higher sorting accuracy and better real-time performance when there are more radar pulses and pulse loss.