INFLUENCE OF NOISE ON THE PROCESS OF QUANTIFYING PERIODIC SIGNALS BY THE DIRECT CONVERSION METHOD

Abstract

In the practice of electrical and radio measurements, voltage measurement is a common operation. This determines the potential difference or voltage drop in the section of the electrical circuit (on its element). The purpose of measuring DC voltage is to determine its value and sign of polarity. When measuring AC voltage, any of its parameters can be determined (amplitude, mean, rms, rectified value or signal scope). The efforts of prominent scientists are aimed at improving the metrological and technical indicators of existing measuring instruments, in particular the development of new methods for correcting the characteristics of the transformation of the measuring channel, which is their main component. However, all these methods focus on converting the amplitude of the periodic signal into an equivalent parameter, followed by converting it into digital code. All this leads to additional conversion errors and requires additional hardware costs. Accordingly, the improvement of known methods for creating new converters of high-frequency periodic signals into code is a promising task at this stage of development of measuring technology. The paper points to noise sources and analyzes the influence of noise during the conversion of the amplitude of periodic signals into code by direct level quantization. It is established that for industrial tomography, the influence of external factors on the probing input signal is practically absent, because the processes of cavitation and chain reaction take place in a closed environment. It was found that the internal noise is related to the technical characteristics and features of each element of the structural diagram of the converter. Analytical expressions for estimating the influence of noise on the measurement process are presented. In the Matlab environment using the Simulink package, a model was developed for visual study of the influence of internal noise on the process of measuring the parameters of the amplitude of the periodic signal. According to the simulation results, the signal / noise dependence on the frequency of the input signal is obtained. Graphic materials are presented, which clearly demonstrate the influence of noise on the amplitude measurement process. It is established that the signal-to-noise ratio does not exceed 63 dB at frequencies of input sinusoidal signals up to 210 MHz at an amplitude value of 1B, which improves the technical performance of the converter.