INVESTIGATION OF THE INTERFERENCE BACKGROUND AT THE INPUT OF THE RECEIVER OF THE NEAR-FIELD MAGNETIC COMMUNICATION SYSTEM IN URBAN CONDITIONS

Abstract

Near-field magnetic communication (NFMC) has unique characteristics, such as secrecy, communication channel security, the ability to pass a signal through the vast majority of obstacles without significant attenuation. NFMC can be used in such use cases where traditional radio is impossible. One of the tasks in which the use of NFMC is relevant is to provide reliable wireless communication for rescuers, firefighters, employees of the Ministry of Emergency Situations when performing their professional activities in the conditions of blockages caused by various destructions of urban buildings. It should be noted that under such conditions, the conductivity of building materials and soil can affect the propagation of not only electric, but also magnetic fields. The fact is that due to the conductivity of such materials, when using radio coupling, eddy currents arise in the materials, which leads to the appearance of a secondary magnetic field that is in antiphase. The system under consideration is not subject to the effects described above. This article presents the results of experimental studies aimed at studying the interference environment in the NFMC channel. Field experiments were carried out to measure the interference environment. Based on the data obtained, it was concluded that the use of NFMC systems in urban environments is a rather difficult task due to the nature of the interference propagating in the channel of this type of communication. The effective use of NFMC requires the development of receiving devices that provide sufficiently strong filtering of signals outside the selected band. Narrow band and high order filtering is key priority of observed communication system.