Abstract
Data sets in the form of time variation of traction current are obtained as a result of an experimental investigation of interference in the channels of automatics and telemechanics systems in railways and subways. Visual assessment of the obtained records suggests the presence of transients in the traction current that are diverse in both amplitude and pulse width. In order to analyze and synthesize noise-resistant receivers of rail track circuits and locomotive devices of the automatic locomotive signaling, it is necessary to construct mathematical models that describe this class of interference. The experimentally obtained histogram should be approximated by an analytical expression that represents a theoretical probability density function that should meet two important conditions, i.e., nonnegativity and normalization. The approximating probability density is selected based on the condition of the conservation of the first four statistical distribution moments for the Pearson family. Twelve types of Pearson curves are described in this paper that depend on the values of individual parameters. Calculation formulas of unbiased estimates of the central moments are given in accordance with statistical data, based on which the appropriate type of the distribution of impulse noise from the traction current is selected. A generalized method of approximation using Pearson curves and a chi-squared test (χ2) for determining the divergence of theoretical and statistical distributions are formulated.
Published Version
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