Comparative Analysis of the Methods for Estimating the Measurement Error of the Amplitude Spectrum Caused by the ADC Nonlinearity

When measuring the spectrum of the periodic signal, the most important instrumental component of the error is the error caused by the nonlinearity of the analog-to-digital converter (ADC) conversion function. This component cannot be eliminated by zero adjustment or calibration of the measurement channel. The procedure for compensation of this error component must be carried out individually for each measuring device, which will result in a significant increase in the final costs. The existing methods provide very overestimated results in comparison with the results of simulation. The article proposes the use of a “combined” method consisting of the nonlinearity representation in the form of three components: “smooth”, “sawtooth” and “pseudo-random”. Analytical relations that allows to calculate the spectrum measurement error at the specified approach to the representation of the ADC nonlinearity are obtained. The comparison of the proposed method of error estimation with the existing methods was performed. The results of simulation modeling are obtained in the Matlab.