How the Telegraph and the Telephone Formed a Worldwide Wired Electromagnetic Environment

The principle of electromagnetic induction was independently discovered by Michael Faraday (England) and Joseph Henry (USA) in 1831–32. The momentous discovery gave birth to numerous inventions that made civilization “modern,” beginning with the telegraph. First the telegraph and then the telephone required the installation of millions of miles of electric wire to cross continents and oceans in order to function as a global telecommunications system. These wires created a wholly new, anthropogenic electromagnetic environment, whose frequencies were orders of magnitude greater than those occurring naturally. Its effects on human beings, particularly inside cities, and the biosphere generally were unknown. Even now, more than a century later, the medical and environmental effects of this worldwide wired infrastructure are at best but partially understood. The telecommunications revolutions of the mid- and late 19th century were eagerly anticipated and implemented swiftly on an unprecedented scale, creating the technological basis for worldwide instantaneous communication. This paper describes the key discoveries that created the scientific and technical breakthroughs that allowed the first telecommunications revolutions to take place.

Research on Continuous Wave Electromagnetic Effect in Swept Frequency Radar

In order to establish the prediction model of radar equipment in multisource complex electromagnetic environment, the blocking effect and false alarm interference effect caused by single-frequency CW (continuous wave) electromagnetic interference on typical radar equipment are studied. Taking a certain sweep radar as the research object, the equivalent injection test of EMI (electromagnetic interference) is carried out. Based on the theory of radar front door coupling, the interference mechanism of EMI to radar receiver RF front end is revealed, and the variation law of blocking target and false alarm target level is analyzed. The results show that, under the single-frequency CW-EMI, the target echo level decreases with the increase of the interference field strength, and the false alarm level increases with the increase of the interference field strength. The blocking jamming sensitive bandwidth is about f 0 ± 200 MHz , and the false alarm jamming sensitive bandwidth is about f 0 ± 80 MHz .

DIGITAL CONTROL SYSTEM OF THE THYRISTOR REGULATOR IN THE NETWORK OF THE METALLURGICAL SHOP

The reasons for the deterioration of the electromagnetic environment in the workshop distribution network of a metallurgical enterprise with powerful valve regulators are considered. A local solution to the problem of improving electromagnetic compatibility is proposed by using a digital microcontroller control system for thyristor regulators of resistance mixers. The effect is achieved due to a more accurate fulfillment of the conditions for switching the gates of each phase at the moment of zero crossing. This allows not only to reduce the level of higher harmonics of the current in the distribution network and improve the symmetry of voltages, but also to increase the stability of the equipment.

MODELING A DC BUS CHARGE CONTROL SYSTEM IGBT INVERTER FOR TWO PHASE LINEAR INDUCTION MACHINE

The problems of modeling in the Matlab environment the modes of the MHD-stirring of aluminum melt in furnaces, taking into account the distribution network. It is noted that the operation of frequency inverters of the power supply system sharply complicates the electromagnetic environment in a network of limited power. It is proposed to apply a complex of models to assess the possibility of reducing the distortion of the network currents by modifying the rectifier control algorithms, while maintaining the stability of the DC bus of the frequency converter.

A Prediction Method of Electromagnetic Environment Effects for UAV LiDAR Detection System

With the rapid development of science and technology, UAVs (Unmanned Aerial Vehicles) have become a new type of weapon in the informatization battlefield by their advantages of low loss and zero casualty rate. In recent years, UAV navigation electromagnetic decoy and electromagnetic interference crashes have activated widespread international attention. The UAV LiDAR detection system is susceptible to electromagnetic interference in a complex electromagnetic environment, which results in inaccurate detection and causes the mission to fail. Therefore, it is very necessary to predict the effects of the electromagnetic environment. Traditional electromagnetic environment effect prediction methods mostly use a single model of mathematical model and machine learning, but the traditional prediction method has poor processing nonlinear ability and weak generalization ability. Therefore, this paper uses the Stacking fusion model algorithm in machine learning to study the electromagnetic environment effect prediction. This paper proposes a Stacking fusion model based on machine learning to predict electromagnetic environment effects. The method consists of Extreme Gradient Boosting algorithm (XGB), Gradient Boosting Decision Tree algorithm (GBDT), K Nearest Neighbor algorithm (KNN), and Decision Tree algorithm (DT). Experimental results show that, comprising with the other seven machine learning algorithms, the Stacking fusion model has a better classification prediction accuracy of 0.9762, a lower Hamming code distance of 0.0336, and a higher Kappa coefficient of 0.955. The fusion model proposed in this paper has a better predictive effect on electromagnetic environment effects and is of great significance for improving the accuracy and safety of UAV LiDAR detection systems under the complex electromagnetic environment on the battlefield.

Expected electromagnetic environment at the energy infrastructure facilities of remote ports (berths)

The article deals with the issues of electromagnetic compatibility of coastal and floating objects in the waters of ports (berths). The subject of the study is the processes occurring in the electrical network when powering ships of the technical fleet and floating objects from the shore, which determine the need for automated calculation of conductive low-frequency electromagnetic disturbance for their subsequent suppression. An algorithm for calculating the parameters of the electromagnetic environment is presented, which is based on the analysis of the distribution parameters of slow voltage changes. The mechanism of EMD occurrence in voltage deviation is described and a mathematical model explaining the probability of its occurrence is presented. An algorithm for calculating the parameters of the electromagnetic environment based on slow voltage changes in the network is compiled. This algorithm is implemented in the “Program for the study of slow voltage changes by the load changingof the electrical network ". For the object under study, the parameters of the distribution of conductive low-frequency electromagnetic disturbance over a slow voltage change are determined. A block diagram of an automatic voltage regulator implementing the proposed voltage stabilization law has been developed.

Detecting Electromagnetic Geographical Environment Changes Based on the Frequency-Intensity Curve

Electromagnetic geographic environment is closely related to human life. With continuous popularization of public infrastructures and daily electronic instruments, such as electric power communication systems and household appliances, electromagnetic radiation sources have increased sharply in the geographic environment, which leads to increasingly serious electromagnetic radiation pollution. Thus, it is significant to monitor, evaluate, and analyze the electromagnetic radiation condition and explore its changing law in the environment. However, the traditional monitoring method can only detect anomalies within certain frequencies in the fixed stations. To fill this gap, this research first develops a vehicle-mounted electromagnetic environment monitoring system to collect both spatial positioning data and electromagnetic data of the whole frequency range. The acquired data are then used to construct the location-based frequency-intensity curve to reflect the variation of electromagnetic radiation at different frequency ranges. On this basis, a curve similarity measurement method is introduced to analyze the similarity of different curves, which is effective to diagnose time-varying sources from both global and local perspectives. This research provides a real-time mobile monitoring method, which is significant to know the dynamic variation of local electromagnetic environment and promotes subsequent comprehensive geographic analyses.