Influence of sample aperture on evaluating harmonics of periodic signals using sampling method

The inherent relationship among frequency of measured signal, aperture time and attenuation of ADC has been revealed through theoretical analysis. A kind of attenuation measurement system which compares the results of asynchronous sampling method and AC/DC transfer method based on thermoelectric conversion is built to verify the relationship. Attenuation is compensated and the consistency between two methods is within 20μV up to 60th harmonic with the fundamental voltage of 0.5V, 50Hz.