EMRP - JOSY: Next generation of quantum voltage systems for wide range applications

• Forschungsstelle: METAS
• Projektnummer: 5211.08.FP.063
• Projekttitel Englisch: EMRP - JOSY: Next generation of quantum voltage systems for wide range applications

Schlüsselwörter (Englisch)

programable ac voltage source, ac measurements, sampling, power standard, ac voltages, ac-dc transfer

Kurzbeschreibung (Englisch)

In the near future, the possibility of measuring electrical signals with an arbitrary waveform will be required. For example, the characterization of the spectral purity of our power network is becoming a really debated topic. The calibration of future instruments will undoubtedly also require such techniques. In the impedance calibration area, numerous new measurement capabilities can also be envisioned using theses new techniques. At present, the ac-dc method allows to measure the rms value of a signal with a great accuracy. However, this method is quite demanding and does not allow to gain information on the waveform or the phase difference between different signals. 

 

Lately, sampling methods were developed to measure ac signals. The goal of this project which is fundamental for the future development of electrical calibration at METAS is to implement these new techniques. The project has two parts: on one side the development of a programmable Josephson ac voltage source which will guarantee the tracability of the measurements, on the other side a “mise en pratique” of the sampling method. 

This project is partly funded by the European Community’s Seventh Framework Programme, ERA-NET Plus under Grant Agreement No 217257.

Projektziele (Englisch)

1. Realisation  of an ac programmable voltage based on binary 1V SINIS arrays. Evaluation of the source by performing measurement with thermal converters between 10 Hz and 1kHz. The measurement uncertainty should be smaller than a ppm in this range.
2. Realisation of a sampling measurement system.
3. Comparison of two programmable ac voltage sources.

Abstract (Englisch)

The development of the Josephson voltage standard locked synthesizer (JoLoS) was completd according to the specifications. The measurement capabilities of the JoLoS digitizer has been evaluated exhaustively with the Programmable Josephson Voltage Standard. Multiple flatspot measurements to test the experimental JoLoS parameters validity range were performed. The JoLoS method is independent of dither current (free of PJVS transients) and independent of the Josephson shape (number of waveform voltage steps). Some limitations have been observed mainly related to the influence of the finite impulse response filter imbedded in the digitizer. These effects can be minimized by selecting a large ratio between the sampling frequency and the waveform frequency. Validation with a calibrated thermal transfer standard (TTS) was conducted at 0.1 V, 0.6 V and 1 V, with frequencies ranging from 10 Hz to 1 kHz. The ac-dc difference of the TTS measured with JoLoS is in excellent agreement with value given by the last TTS calibration. All the ac-dc measurements obtained are within the calibration uncertainties. With these results the amplitude inferred with JoLoS is successfully validated over the range tested. The JoLoS with amplitude feedback can be used has a source to drive low impedance with an uncertainty below 1.5 µV/V, ranging from 100 mV to 1 V and 10 Hz to 1 KHz.

Umsetzung und Anwendungen (Englisch)

As soon as a commercially available 10 V SNS array is on the market, the JoLoS will be used to perform AC calibration of DVM, calibrators, thermal transfer standard, up to 10V and for frequencies up to 1 kHz. In addition this instrument will also be useful in future research project in the domain of impedance and power measurements.

Publikationen / Ergebnisse (Englisch)

B. Jeanneret, F. Overney, L. Callegaro, A. Mortara and A. Rüfenacht, Josephson-Voltage-Standard-Locked Sinewave Synthesizer: Margin Evaluation and Stability, IEEE Trans. Instrum. Meas. 58-4, 791 (2009).
B. Jeanneret, F. Overney, A. Rüfenacht and J. Nissilä, Strong Attenuation of the Transients’ Effect in Square Waves Synthesized with a Programmable Josephson Voltage Standard, IEEE Trans. Instrum. Meas. 59-7, 1894 (2010).
A. Rüfenacht, F. Overney, A. Mortara and B. Jeanneret, Thermal Transfer Standard Validation of the Josephson-Voltage-Standard-Locked Sine Wave Synthesizer, accepted for publication in IEEE Trans. Instrum. Meas. (2011).
B. Jeanneret, A. Rüfenacht, R. Behr, P. M. Fleischmann, M. Mühl, S. Inam, On-site calibration with the METAS Josephson-locked synthesizer at ESZ AG Calibration & Metrology, Eichenau, Germany, 18 to 22 October (2010), Internal JoSy iMERA+ Project Report.
F. Overney, A. Rüfenacht, J.-P. Braun, B. Jeanneret and P.S. Wright, Characterization of Metrological Grade Analog-to-Digital Converters using a Programmable Josephson Voltage Standard, accepted for publication in IEEE Trans. Instrum. Meas. (2011).
B. Jeanneret, A. Rüfenacht and F. Overney, H. van den Brom and E. Houtzager, Direct high precision comparison between a programmable and a pulse driven Josephson voltage standard, accepted for publication in Metrologia (2011).