The Josephson-Effect-Based Primary AC Power Standard at the PTB: Progress Report
ABSTRACT This paper reports the incorporation of a Josephson waveform synthesizer (JWS) into the primary standard for AC electrical power at the Physikalisch-Technische Bundesanstalt (PTB). The increase to 10 V of the amplitude delivered by the JWS has allowed matching of the levels of the signals measured to determine the active, reactive, and apparent power-at the 120-V and 5-A level, which is also measured by the device under test. The inherent noise- and drift-free voltages delivered by the JWS allow calibration of the core sampling voltmeter of the PTB primary power standard with an uncertainty of 0.4 muV/V(k = 1) in 100 signal periods and as part of the measuring sequence.
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ABSTRACT: In an extension from their original use as references for measuring dc voltage, Josephson generated voltages from programmable arrays have been employed to measure waveforms differentially. In this paper, the alternative of using these Josephson voltages as a reference for ac-dc difference measurements using thermal converters and sampling techniques is presented.01/2010;
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ABSTRACT: The discovery of the Josephson effect has for the first time given national metrology institutes (NMIs) the possibility of maintaining voltage references which are stable in time. In addition, the introduction in 1990 of a conventional value for the Josephson constant, KJ-90, has greatly improved world-wide consistency among representations of the volt. For 20 years, the Bureau International des Poids et Mesures (BIPM) has conducted an ongoing, direct, on-site key comparison of Josephson voltage standards among NMIs under the denominations BIPM.EM-K10.a (1 V) and BIPM.EM-K10.b (10 V) in the framework of the mutual recognition arrangement (CIPM MRA). The results of 41 comparisons illustrate the consistency among primary voltage standards and have demonstrated that a relative total uncertainty of a few parts in 1010 is achievable if a few precautions are taken with regard to the measurement set-up. Of particular importance are the grounding, efficient filters and high insulation resistance of the measurement leads, and clean microwave distribution along the propagation line to the Josephson array. This paper reviews the comparison scheme and technical issues that need to be taken into account to achieve a relative uncertainty at the level of a few parts in 1010 or even a few parts in 1011 in the best cases.Measurement Science and Technology 11/2012; 23(12):124001. · 1.35 Impact Factor
Conference Paper: Ultrapure sinewave generation by combining Josephson systems[Show abstract] [Hide abstract]
ABSTRACT: The combination of systems exploiting binary-divided and pulse-driven Josephson arrays allows the generation of sinewaves with amplitudes of up to 10 V and very low harmonic distortion (-122 dBc). We present results from the combination of a 1 V binary divided Josephson array employed as a multilevel digital to analogue converter and a pulse driven array that is programmed to cancel the harmonic content present in the stepwise approximated output of the binary array. The synthesized waveform can be locked to a timing reference for ultimate frequency stability. The quantum nature of the Josephson synthesizers guarantees the stability of the amplitude. The unprecedented amplitudes available with this spectral purity open new possibilities for testing of electronic modules and analogue to digital converters19th IMEKO TC-4 Symposium and 17th IWADC Workshop, Barcelona; 07/2013