Jamming Conditions Research Articles

Optimal power allocation‐based novel control jamming scheme for nonorthogonal multiple access enabled decode‐and‐forward relay network

SummaryIn this work, a new control jamming (CJ) scheme has been proposed for a cooperative nonorthogonal multiple access (NOMA) network with optimal power allocation factors by employing decode‐and‐forward (DF) relay. Maximization of secrecy rate at both NOMA users with the aid of CJ under total transmit power constraint is considered as an optimization problem. In this regard, invasive weed optimization (IWO) algorithm‐based approach is proposed to facilitate optimal power allocation for the considered network. In this analysis, performance metric secrecy rate is analyzed with CJ at both NOMA users by varying the location of eavesdropper with respect to the relay and jammer. In addition, the performance of fixed power allocation (FPA) and proposed power allocation (PPA) schemes is investigated with CJ and compared with jamming (J) and without jamming (WJ) conditions. Simulation result analysis specifies that secrecy performance is enhanced remarkably by CJ and PPA outperforms the FPA.

Joint angle and range estimation for bistatic FDA-MIMO radar via real-valued subspace decomposition

The frequency diverse array (FDA) is mainly applied to achieving target localization under the complicated electromagnetic jamming condition. The bistatic multiple-input-multiple-output (MIMO) radar with FDA has gained comprehensive attention in recent years. An innovative method covering the transmitting subarray scheme and the unitary estimation of signal parameters via rotational invariance technology (ESPRIT) is proposed for joint direction of departure (DOD), direction of arrival (DOA), and range estimation. First, a non-overlapping subarray scheme is designed for the transmitting array to decouple DOD and range. For the purpose of enhancing the estimation accuracy and reducing the computational complexity, the real-valued rotational invariance matrix is obtained via applying the unitary transformation to the extended data. The removal method is proposed to avoid the periodic phase ambiguity. The pairing method is put forward to achieving the match of three-dimensional parameter (DOD, DOA and range) for multiple targets. The computational complexity of the proposed algorithm and conventional ESPRIT algorithm are also provided. Finally, extensive experiment results indicate that the proposed algorithm shows the superior performance than the ESPRIT algorithm.

Analysis of jamming conditions during robotic assembly of profi le connections

The results of theoretical and experimental studies of jamming conditions during the assembly of profi le jounts are presented. A mathematical model of the conjugation process in a quasi-static setting is considered. The data obtaine d from the model allows you to determine the boundary conditions that determine the occurrence of wedges. A method for increasing the reliability of the assembly of profi le connections based on adaptation tools is considered. The adequacy of the analytical solution and the results of the physical experiment is discussed.

An experimental approach to comparative thermal behavior of rubber and metallic clutch dampers

Clutch is one of the most important components in automobile powertrain systems. The torque generated in an engine is transmitted by friction faces of a clutch disc between pressure plate and flywheel. In addition to transmitting engine torque, the clutch disc has the task of preventing torsional engine vibrations from reaching the powertrain. To achieve this task, the clutch disc is fitted with torsional dampers which have metallic compression springs. Another solution is to use rubber springs instead of metallic ones. Recently rubber materials are widely demanded particularly in the automotive industry with the advantages of high damping capability, lightweight and low cost. In a traffic jam condition, numerous engagement and disengagement create incremental thermal load and temperature increase due to slippage between friction faces. The temperature level in the clutch house is expected to affect material properties of damping components assembled inside the clutch disc. In this paper, the rubber and metallic damper springs were investigated experimentally at the expected temperatures and dynamic loads during driving conditions. Thus, the thermal behavior of rubber springs in the clutch system was observed with the novel approach. Damper torque characteristics, cooling rates and loss of stiffness change with time and frequency have been revealed comparatively. Safety factor coefficient selection for damper torque has the major importance at the system in which the stiffness varies within time due to dynamic loads. In conclusion, the clutch disc used with rubber springs needs correct analysis in terms of design. Results show that how to safety actor should be chosen more attentively for clutch disc used with rubber spring on automobiles and related calculations have to be done before the design phase.

Modeling of jamming phenomenon in fixture design application: an analytical, numerical, and experimental study

Jamming may occur during the loading of the workpiece in the fixture and cause an improper locating process or damage to the workpiece, fixture, and loading system. Consideration of the jamming phenomenon is a necessary task in the planning of the workpiece loading strategy. In the present paper, the minimum norm principle is used to present an analytical model for predicting the jamming occurrence conditions through calculating reaction forces at the contact points. The implementation of this model results in an optimization problem that is solved using the augmented Lagrange multiplier method. The proposed model is applied to two well-known jamming problems, namely the peg-in-hole and block and palm configurations. Numerical analysis is also conducted in Adams software to verify the theoretical predictions. Finally, the experimental setups are fabricated for these configurations to validate the theoretical predictions and numerical results. The results show that the maximum errors between the theoretical predictions and experimental results are 14.4% and 3.8% for the jamming-out angle in the peg-in-hole study and jamming-in travel in the block and palm problem, respectively. Moreover, the worst-case error of 6.9% is obtained for the theoretical prediction of the jamming-in travel of block compared to the numerical result. Agreement between the theoretical, numerical, and experimental results proves the capabilities of the suggested model in the accurate prediction of the jamming occurrence conditions and its potentials for use in the three-dimensional jamming-prone fixturing systems.

Synthesis of an Interference-Resistant Space-Time Filter for High-Precision Measurements of Navigation Parameters According to the Signals of Global Navigation Satellite Systems

We study the problems of serviceability of contemporary high-precision terminals of global navigation satellite systems under the conditions of jamming and spoofing interferences. The application of digital antenna arrays with algorithms of space-time signal processing of the signals can be regarded as a solution of the problem of low interference resistance. We describe well-known, most studied, and currently applied algorithms of space-time signal processing. We also formulate the causes that do not enable one to use well-known algorithms in high-precision terminals of satellite systems of global navigation. We propose an algorithm of space-time signal processing based on a space-time filter of finite length with a theoretically justified requirement of Hermitian symmetry for the matrix impulse response. The proposed algorithm guarantees the absence of distortions of signals under any signal and interference conditions. In this case, the impulse response of the space-time filter is computed according to the criterion of optimal suppression of the interference. The characteristics of the proposed space-time filter and other algorithms of space-time signal processing are investigated. For this purpose, we apply the method of mathematical simulation with random search of numerous parameters of signals and interferences (directions to signals, directions to numerous interferences, and to their reflections, remoteness of the reflectors of interferences, the phases of reflections, and the levels of interferences and reflections, etc.). The results of simulations are presented in the form of the distribution functions of the signal-to-interference ratios at the output of the algorithms of space-time signal processing and the distribution functions of the phase and signal-time biases. The obtained dependences substantiate the absence of the phase and signal-time biases in the space-time filter for any signal and interference conditions with interference multipath. It is shown that the space-time filter guarantees a higher interference resistance than the compensating algorithms of space-time signal processing.

Efficiency Evaluation of Air-defense Early-warning Detection Based on Communication Support

In order to quantitatively analyze the impact of communication support capability on early-warning detection efficiency under electronic jamming condition, based on the study of the air-raid targets searching process, this paper build the detection probability calculating model of target indicating radar by evaluating the jamming efficiency of the air intelligence informing communication. Combined with the typical combat scenario, analysis of examples simulation is done and the results show that the jamming effect of using airborne jamming is better than using subgrade jamming on communication and the target indicating error which is caused by early-warning information does not affect the improvement of early warning detection capability.

Policies for Transmit Power Controlin the Conditions of Jamming in Clustered Wireless System

Policies for Transmit Power Controlin the Conditions of Jamming in Clustered Wireless System

An Efficient Ultra-Tight GPS/RISS Integrated System for Challenging Navigation Environments

The Global Positioning System (GPS) provides an accurate navigation solution in the open sky. However, in some environments such as urban areas or in the presence of signal jamming, GPS signals cannot be easily tracked since they could be harshly attenuated or entirely blocked. This often requires the GPS receiver to go into a signal re-acquisition phase for the corresponding satellite. To avoid the intensive computations necessary for the signal re-lock in a GPS receiver, a robust signal-tracking mechanism that can hold and/or rapidly re-lock on the signals and keep track of their dynamics becomes a necessity. This paper augments a vector-based GPS signal tracking system with a Reduced Inertial Sensor System (RISS) to produce a new ultra-tight GPS/INS integrated system that enhances receivers’ tracking robustness and sensitivity in challenging navigation environments. The introduced system is simple, efficient, reliable, yet inexpensive. To challenge the proposed method with real jamming conditions, real experiment work was conducted inside the Anechoic Chamber room at the Royal Military College of Canada (RMC). The Spirent GSS6700 signal simulator was used to generate GPS signals, and an INS Simulator is used for simulating the inertial measurement unit (IMU) to generate the corresponding trajectory raw data. The NEAT jammer, by NovAtel, was used to generate real jamming signals. Results show a good performance of the proposed method under real signal jamming conditions.

Three-dimensional braided composites with zero, negative and isotropic thermal expansion behavior

Three-dimensional braided composites with zero, negative and isotropic coefficient of thermal expansion are presented based on an analytical homogenization technique. The configuration of the braided composites is worked out considering the exact jamming condition leading to higher fiber volume fraction. A total of four configurations of three-dimensional-braided composite representative unit cells were analyzed. Among these, two arrangements are 4-axes and the other two are 5-axes. Special emphasis is given on the detailed description of the representative unit cells. Analysis reveals that a three-dimensional-braided composite configuration with thermoelastic isotropic properties having same coefficient of thermal expansion along x-, y-, and z-axes is achievable. As a special case, the homogenization model is used to predict, for the first time, a configuration of braided architecture and material leading to zero coefficient of thermal expansion along x-, y- and z-directions.

Antijamming Receiver With Hybrid Blanking—Clipping for DCSK System

Although investigating performances of existing chaotic communication systems (CCSs) and proposing new CCSs have been extensively investigated, designing antijamming (AJ) receivers for CCSs has been rarely considered. AJ receivers for CCS are of paramount importance in cases that the inherent AJ capability of CCSs does not work well, i.e., when the power of jamming signals is larger than that of chaotic signals. Motivated by this fact, in this article, we consider a differential chaos shift keying (DCSK) system under a Gaussian pulse jamming condition. We propose an AJ receiver with a hybrid blanking-clipping mechanism to enhance the AJ performance of the considered system. We also derive closed-form expressions of the signal-to-interference-plus-noise of the outputs of the blanking and clipping blocks, which are then to be used to obtain optimal blanking and clipping thresholds for additive white Gaussian noise (AWGN) channel. Moreover, an optimal weighting factor used for combining the outputs of the blanking and clipping blocks is also provided. We show that the proposed receiver considerably outperforms existing receivers.

Novel jamming mechanism for dry separation of particles by density

Previous work on a novel separation device called the Sink-Hole Fluidizer has been extended to investigate the effect of increasing the Sink-Hole diameter from 13 mm up to 60 mm. This device consists of a pair of mesh screens with 1 mm square apertures mounted above the surface of a vibrated fluidized bed. The upper mesh contains a large central hole referred to as a Sink-Hole. The fluidized granular media, nominally 0.2 mm sand particles, expanded up through the large Sink-Hole, spread radially and deposited across the upper mesh, and then sifted back into the lower fluidized zone. The effective density of the medium at the mouth of the Sink-Hole was determined by examining the probability of large tracer particles of a given density floating over or sinking through the Sink-Hole. It was seen previously for a 13 mm diameter Sink-Hole that the separation density exceeded the bulk density of the fluidized medium, and often also even the skeletal density of the granular media itself. Similar results were achieved here, even for a significant increase in the Sink-Hole diameter up to 60 mm. Moreover, the separation density was largely independent of the size of the tracer particles covering the range 2.8 to 8.0 mm, a sign of genuine density-based separation. The underlying mechanism was attributed to a self-organised, tenuous, jamming condition that develops at the mouth of the Sink-Hole. As the diameter of the Sink-Hole increased, the separation density decreased, while the speed at which the sorting of the test particles occurred increased significantly. A 60 mm diameter Sink-Hole achieved a steady state separation within approximately 10 s, and a remarkably sharp density-based separation.

An Improved Smart Traffic Signal using Computer Vision and Artificial Intelligence

The growth in population all over the world and in particular in India causes an increase in the number of vehicles which, create complications regarding traffic jam and traffic safety. The primary solution to recover the jam condition is the expansion of capacities of roads by building new streets. However, this requires extra efforts and more time that is a costly and ineffective solution. Therefore, there is a need for alternative solution methodologies that are being implemented. Intelligent traffic monitoring is a branch of intelligent transportation systems that focuses on improving traffic signal conditions. The key goal of such an intelligent monitoring system is to improve the traffic system in a way that reduces delays. Many cities facing these delays because of the inefficient configuration of traffic light systems which are mostly fixed-cycle protocol based. Therefore, there is a profound need to improve and automate these traffic light systems. The establishment of a mixed technique of artificial intelligence (AI) and computer vision (CV) can be desirable to develop an authenticated and scalable traffic system which can aid to solve such problems. Proposed work supports the use of computer vision technology to build a resource-efficient, synchronous and automated traffic analysis. Video samples were collected from multiple areas to use in the system. The system applied and the vehicle was counted and classified into different classes. Manually and automatically annotated patterns were used for the classification. The multi-reference-line mechanism employed to find the speed of the vehicle and analyze traffic. The system makes its decision based on a number of vehicles, backwards-forward synchronous data and emergency conditions.

Novel correlation to evaluate the pressure losses for different traffic jam conditions in road tunnel with alternative jet fan, second part

The aim of this study is to provide a novel correlation to evaluate the pressure loss, in road tunnel, for different traffic jam conditions (Filling Tunnel Traffic, FTT). The proposed correlation refers to a longitudinal ventilation system of innovative impulsive jet fan with silencers inclined toward tunnel floor. This innovative design solution reduces the Coanda effect and, consequently, the pressure loss, requiring thereby less electrical power with respect to the traditional one. The jam vehicles, equally spaced, are considered as asperities whereby, the correlation provides a kind of “friction factor” due to vehicles as function of FTT. The pressure loss caused by vehicles depends on the roughness and aerodynamic coefficient of vehicles surface and depends also on vortices between the vehicles. This “friction factor” can be used to compute the pressure loss due to vehicles and added to the wall friction, providing the “total friction factor”. The novel correlation, here proposed, is useful to the designer to size the innovative ventilation system because there are no data in literature or in technical reports about the interaction between the air flux ejected from the inclined jet fan and cars. This work is the extension of an antecedent one (Cascetta et al., 2019) in which the novel correlation has referred to a longitudinal ventilation system equipped with traditional impulsive jet fan.

Jamming Resistance of the Inbound Channel of an Identification System with Broadband Signals and Error Control Codes in the Conditions of Pulse Noise and Intra-System Jamming

Results of an assessment of a noise stability of the request channel of a radar-tracking identification with broadband signals in the conditions of pulse noise and intersystem hindrances are given. Optimum alarm and code designs of orthogonal broadband signals decide on Read-Solomon’s correcting codes for various characteristics of influencing hindrances

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.

A linear guide-based actuation concept for a novel morphing aileron

ABSTRACTThis paper deals with the actuation system design of a full-scale morphing aileron for regional aircraft. The aileron is allowed to smoothly change its geometrical configuration and perform the in-flight transition from a baseline shape to a set of optimal morphed ones pre-defined on the basis of aerodynamic requirements. The design of such innovative aileron is aimed not only at substituting the conventional aileron installed on a real aircraft but also to provide additional functionality. The aileron is free to rotate around its main hinge axis and it is also allowed to smoothly modify camber with two independent actuation systems. In such manner it can be used also during cruise with a symmetric deflection between the two half wings in order to reduce drag in off design condition. To accomplish variable aileron shape, a rigid-body mechanism was designed. The proposed aileron architecture is characterised by segmented adaptive ribs rigidly linked each other with spanwise reinforcements such as spars and stringers in a multi-box arrangement. Each rib is split into two movable plates connected by means of rotational hinges in a finger-like mechanism. The mechanism is driven by a load-bearing actuator by means of a kinematic chain opportunely tied based on the structural requirements in terms of shape to be matched and load to be withstood. The proposed device is an innovative arrangement of the quick-return mechanism composed of a beam leverage, commercial linear guides and a crank. The actuator shaft is directly inserted in the crank, which transmits the rotation to the linear guide that slide along a rail moving upward or downward the beam thus resulting in a camber variation. The entire aileron is moved by three leverages internally contained and distributed along the first two bays while the most external ribs are considered passive and their movement slaved. Two actuation layouts are analytically and numerically studied, the analytical theory is presented and validated by means of a multi-body simulation. Moreover, a linear static analysis was carried out under the hypothesis of glued contact between linear guides components simulating a jamming condition. This assumption has been formulated because it represents the most severe condition that envelop all the operative loads to which the actuation system is subjected. The analyses conducted are preliminarily aimed to verify that no failure occur under the imposed loads. In this first design loop, the vertical static force acting on the linear carriage exceeded allowable value and then a new configuration with double-sided linear guides was then investigated.

Frame synchronization for pulsed jammed satellite telecommand links

SummaryA new issue of the satellite telecommand synchronization and channel coding sublayer protocol includes LDPC‐coded communication link transmission units (CLTUs) that contain a 64‐bit start sequence. The novel data structures allow operation at lower signal‐to‐noise ratios than before and offer improved protection against jamming attacks. This paper considers the corresponding CLTU frame synchronization process. We derive practical algorithms to locate the start sequence in the presence of high noise levels and pulsed jamming. The different algorithms are compared in terms of implementation complexity and performance under various jamming conditions. It is shown that among the considered frame synchronizers, those involving a full search over the entire observation window provide the desired accuracy, ie, they guarantee a frame synchronization error probability that is significantly smaller than the codeword error rate, for codeword error rates near a target value of 10−4. Among these synchronizers, the full‐search hard‐decision–directed correlation‐based algorithm has the lowest complexity.

물리계층 보안 성능 향상을 위한 재밍 조건

물리계층 보안기법은 무선 채널의 통계적 특성에 의존하지 않는 인공노이즈 기법과 결합되어 MIMO 시스템, 멀티유저, 릴레이 시나리오 등 다양한 모델에서 연구되고 있다. 하지만 정교하게 수립되지 않는 무분별한 재밍 전략은 오히려 보안성능을 감소시키기 때문에 성능에 영향을 주는 요소들을 이론적으로 분석해야 한다. 따라서, 본 논문에서는 도청자가 존재하는 MIMO 채널에서 재밍파워와 노드배치의 관점에서 보안성능의 변화를 살펴보았다.

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.