A direct comparison of the 10 V Josephson Voltage Standards (JVS) of the National Institute of Standards and Technology (NIST), USA and the National Institute of Metrology, Standardization and Industrial Quality (INMETRO), Brazil was made in June 2009. The process consisted of two comparisons, first using the NIST CJVS s measuring system (hardware and software) to measure 10 V reference voltage provided by the INMETRO JVS and then using the INMETRO JVS s measuring system to measure the 10 V reference voltage provided by the NIST CJVS. The results of the two comparisons were in agreement to within 1.1 nV and their mean indicated that the difference between the two JVSs at 10 V was 0.54 nV with a combined standard uncertainty of 1.48 nV or a relative standard uncertainty of 1.48 parts in 10^10.
Pub Type: Journals
CIPM-MRA key comparison, direct comparison, Josephson voltage standard, uncertainty