Uncertainty Analysis of Impedance Measurements in the Sampling Sensor Instrument
Jerzy Augustyn
Abstract:
The algorithms based on digital signal processing for impedance components’ evaluation in circuits with sampling transducer have been analysed. It is supposed that the voltage and current are sampled synchronously to the fundamental frequency of the generated sinusoidal signal. Two fitting sine wave algorithms, which are based on the least mean square (LMS) technique, have been described. The first one reconstructs indirect measurement method. The second algorithm estimates the unknown impedance components by direct method. The uncertainty’s propagation by described algorithms can be analysed by means of covariance matrix. The elements of covariance matrix are dependent on the phase angles of the measurement signals. It is shown that those algorithms provide minimization of uncertainty for selected number of samples and phase angles. The influence’s simulations of quantization error of the AD converter and jitters of sampling time for described algorithms on uncertainty processing results have been carried out.
