ADAPTIVE ESTIMATION AND DETECTION OF HAZARDOUS SIGNALS IN POWER SUPPLY LINES OF AN INFORMATION ACTIVITY FACILITY

Abstract

The article considers the problem of synthesizing an adaptive receiver for hazardous signals in a 220 V, 50 Hz power supply line at an information activity facility (IAF). It is shown that, after filtering the power-frequency component and its harmonics, the residual interference may exhibit non-Gaussian, impulsive, and multimodal characteristics, causing the detector likelihood function to have several local maxima. A quasi-optimal approach to the joint detection and estimation of a hazardous signal is proposed. The approach is based on representing the posterior probability density as a weighted sum of partial components, forming local estimates of the information parameter, and Bayesian updating of the weighting coefficients. A structural implementation of the adaptive receiver has been developed, comprising preliminary filtering, interference environment analysis, partial processing, aggregate estimation, and decision-making units. To verify the proposed approach, simulation modeling was performed for a bimodal Gaussian mixture. For a given false-alarm probability, the proposed mixture-based detector provided the required probability of correct detection and, compared with a detector based on an equivalent Gaussian model, reduced the mean-square error in estimating the hazardous signal level by approximately four times. The obtained results confirm the feasibility of accounting for the multimodal nature of interference when conducting special investigations (SI) of wired technical information leakage channels through power supply lines at an information activity facility.