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Differential sampling measurements of low-frequency sinusoidal waveforms using AC-programmable Josephson voltage standard

We have carried out the differential sampling measurements of low-frequency sinusoidal waveforms synthesis based on an AC-programmable Josephson voltage standard (AC-PJVS) system and a modified digital voltmeter. We also have performed a variety of measurements to evaluate this differential sampling technique. Evaluation results show that the overall uncertainty of this AC-PJVS system is (0.2 to 8) μV/V (k=1) for the rms amplitudes of (0.1 to 7) V with the frequency range of (1 to 500) Hz generated by the calibrators. Our measurement results above 20 Hz are in good agreement with the results obtained by the conventional method of the ac-dc transfer differences within their measured uncertainties (k=2).