Research on differential sampling method with 10 Volt programmable josephson voltage standard at NIM

This paper describes a differential sampling method which uses a commercial sampling Analog Digital Converter (ADC) and the Programmable Josephson Voltage Standard (PJVS) to measure the ac voltages provided by the Fluke 5720A calibrator. Since this sampling technique discards the samples that contain the unpredictable transients between the quantized voltage steps within the stepwise approximate ac voltage generated by the PJVS, the error contributions of the transients to the measurement results can be greatly reduced. This is an important way for the dissemination of the ac voltage generated by the PJVS system. The experimental results show that, after averaging, the measurement uncertainty of a ac voltage with the amplitude of 0.707 Vrms at 60 Hz is less than 1 µV (type A).