Use of precise digital voltmeters for phase measurements

The possibility of using high-resolution digital voltmeters (DVs) for ac vo ltage measurements at a frequency of about 16 Hz is presented. The method o f approximate synchronous sampling is used where each sample is measured as the mean value of the one-third cycle of a period. From the samples, the r ms value of the "derived" sine is determined using subsequent numeric synch ronization, while the phase angle of the first sample is calculated as regr ession line coefficient, Corrections of phase differences between two voltm eters were determined using only one source in cascade measurements.