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We present an empirical method of measuring geometric noise in matrix photoreceptors included in an intelligent system developed for detecting obstacles in the path of a train. A reference calibration field uses thermal images of crossties. Measurement of geometric noise sensitivity and dark current is based on selected levels of homogeneity in the reference image. The experimental results demonstrated the advantage of the proposed method compared to a conventional two-point calibration. [ABSTRACT FROM AUTHOR]

comparative analysis of methods of measuring reactive power for ac networks is carried out. Analytic relations for the systematic error as a function of the current and voltage parameters are obtained. For the method based on a Hilbert converter, the complexities of its practical realization are considered. It is shown that for ac networks, the method based on the discrete Fourier transform of the current and voltage is the most accurate. [ABSTRACT FROM AUTHOR]

In modern calibrators of instruments for measuring electric-power quality, the voltage is reproduced by direct digital synthesis (DDS) of the signal. The main structures and methods of regulating the frequency of the output signal of DDS-synthesizers are considered. It is shown that, for a number of parameters, the frequency regulation method, when the reference frequency of the digital-to-analog converter is varied using a DDS generator, is the most preferable. [ABSTRACT FROM AUTHOR]