Assessment of Dynamic Errors of Input Circuits in Measuring Systems when Setting Line Interference Filters

To reduce the line interference effect in measuring systems (MS) the analog line filters (AF), located in the input circuits, or digital line filters (DF), implemented as a program in the input module Min after the analog-to-digital conversion (ADC) are used. In case of multichannel measurements, when the result is determined by the signals of several spaced sensors, the errors related to the unequal signal delays arise. The article deals with the dynamic errors of the MS input circuits, which occur due to the signal delay of the primary transducer of the sensor in line filters. The line jamming situation in the MS is assessed, the problem of reducing the line interference effect is defined for various combinations of signal spectra at the input of the unifying converter of the sensor and at the input of the input module Min, as well as the spectrum and amplitude of the line interference. To solve this problem, the functional circuits of analog (ARF) and digital (DRF) rejection filters were studied and the dynamic error of the main line filter modifications was estimated. It is shown that the ARFs with a Wynn-Robinson bridge have a minimum value of the dynamic error, which is determined by the frequency properties of the applied operational amplifiers (OA).