Implementation of Fluke 8588A multimeter for differential sampling of AC waveforms based on a programmable Josephson voltage standard

We have implemented a multimeter Fluke 8588A as a sampler for the differential sampling of AC waveforms based on a programmable Josephson voltage standard. The bandwidth of the input low-pass filter for the multimeter in the digitizing mode can be set to two different values, 100 kHz and 3 MHz. To investigate the effect of the bandwidth on the differential sampling, we measured outputs of an AC source in the frequency range of 31.25 Hz ≤ f ≤ 1 kHz. We found that RMS amplitudes obtained with the multimeter in the 3 MHz bandwidth for the 1 V output of the AC source are scattered within 3 μV/V in the frequency range. However, the RMS amplitudes obtained in 100 kHz bandwidth, deviates more and more from that obtained in the 3 MHz bandwidth as the frequency increases, which can be roughly described as a quadratic function of f. In the conference, we will present the measurement results obtained to explore the possibility of using the multimeter for reliable differential sampling over a frequency range well above 100 Hz.