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(a) VF for the AC waveform (1 V at 62.5 Hz) generated from the Type-I AC source, measured by differential sampling with the integrating sampler. The measurements were performed intermittently for a period of approximately two months in Mode A, Mode B, and Mode C. Each data point represents a mean of 25 or more measurements with the Type A uncertainty. Detailed sampling parameters for data points are represented in table 1. (b) Comparison of the VF values obtained in Mode A and Mode C. (c) Comparison of the VF values obtained in Mode A and Mode B.
Source publication
A measurement setup for differential sampling of AC waveforms based on a programmable Josephson voltage standard, with an integrating sampler, Keysight 3458, and a Δ-Σ analogue-to-digital converter, NI PXI-5922, is described. The system operates in several circuit configurations with different synchronization and triggering schemes. In particular,...
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Citations
... The National Institute of Standards and Technology (NIST) experimentally verified the feasibility of AC voltage measurement by the differential sampling method based on PJVS for the first time with two sets of PJVS systems in 2008 [7]. Over the past decade, several national metrology institutions (NMIs) such as PTB [5,8], NIST [7,9,10], Korea Research Institute of Standard and Science (KRISS) [11][12][13], National Institute of Advanced Industrial Science and Technology (AIST) [14,15] and the National Institute of Metrology (NIM) [16] have conducted research on differential sampling systems based on PJVS to measure AC voltages. The process of differential sampling based on PJVS for AC waveform measurement is shown in Figure 1. ...
... The process of differential sampling based on PJVS for AC waveform measurement is shown in Figure 1. Commonly used samplers by NMIs include Keysight 3458A [7,[9][10][11][12][13]15,17], NI PXI cards 5922 [8,12,13,18,19] and 4461 [18,19], and Fluke 8588A [13]. Various countries have different post-processing algorithms to meet different application requirements [20]. ...
... The process of differential sampling based on PJVS for AC waveform measurement is shown in Figure 1. Commonly used samplers by NMIs include Keysight 3458A [7,[9][10][11][12][13]15,17], NI PXI cards 5922 [8,12,13,18,19] and 4461 [18,19], and Fluke 8588A [13]. Various countries have different post-processing algorithms to meet different application requirements [20]. ...
The effect of phase jitter on differential sampling using the programmable Josephson voltage standard (PJVS) system is studied in this paper. A phase jitter model is established for the measured signal, and compensation coefficients for phase jitter removal are derived for three different post-processing methods based on the discrete Fourier transform algorithm (DFT). Based on our analysis, the phase jitter compensation coefficients are determined by the phase jitter angle distribution and harmonic order. Furthermore, after analyzing and simulating various common distributions, the phase jitter compensation coefficients have been verified. The simulation shows that when the standard deviation of the phase jitter angle is 20 ns, and the frequency of the measuring waveform is 3.46 kHz, the influence of the phase jitter is 1 × 10−7. The results of the simulation indicate that, in the differential sampling of AC waveforms using a PJVS system, phase jitter is one of the error terms for an uncertainty budget that cannot be neglected, particularly as the frequency of the measured waveforms increases.
... The main limitation of PJVS lies in the time taken for the output voltage switching: during these transients, the array voltage is not quantum-defined, thereby restricting PJVS arrays to meet the requirements of primary metrology uncertainties only for signals up to a few kHz. In spite of this, PJVS have been shown capable of calibrating precision ac voltage sources using selective differential sampling techniques [8][9][10][11], achieving considerably lower uncertainties compared to thermal voltage converters (TVCs), down to one part in 10 8 at 1 V and 250 Hz [12]. Frequency extension of PJVS calibrations up to 100 kHz is also under investigation by means of differential sub-sampling [13,14]. ...
... In recent years, differential sampling based on a PJVS as a reference for measuring AC signals has been widely used in national metrology institutions (NMIs) [4][5][6][7]. Using the quantized step of the stepwise approximated waveforms generated by PJVS, the differential sampling method can accurately measure the unknown AC voltage with the transients discarded [8][9][10][11][12][13]. However, the PJVS system requires liquid helium for operation, and AC voltage calibration with it is complex and costly [8]. ...
... The Keysight 3458A is well known for its superior linearity and transfer accuracy in standard DCV mode [13]. To make the most of its excellent performance in this mode and reduce gain deviations when measuring AC signals, this paper proposes a differential sampling method that uses a commercial DAC (which is in one channel of the NI 6733) as a Sensors 2024, 24, 2228 2 of 14 reference to determine the amplitude and phase of AC waveforms. ...
... Furthermore, the effect of this limited bandwidth (150 kHz) of the sampler cannot be negligible. As [13,23] shows, the uncertainty due to the limited bandwidth is about 0.1 µV/V at the frequency of 50 Hz. ...
This paper introduces an innovative differential sampling technique for calibrating AC waveforms, leveraging a commercially available 16-bit digital-to-analog converter (DAC) as the reference standard. The novelty of this approach lies in its enhanced stability over traditional direct sampling methods, especially as the frequency of the AC waveform increases. Notably, this technique provides a cost-effective sampler alternative to the differential sampling methods that rely on a programmable Josephson voltage standard (PJVS). A critical aspect of this methodology is the precise measurement of the DAC’s output voltage, for which a static measurement strategy is adopted to utilize the exceptional linearity and transfer accuracy of the Keysight 3458A (Santa Rosa, CA, USA) in its standard DCV mode. The differential sampling method has demonstrated good accuracy, achieving a near 1 µV/V agreement with a pulse-driven AC Josephson voltage standard (ACJVS) across a 40 Hz to 200 Hz frequency range. The method attained an expanded uncertainty (k = 2) of 1 part in 106 while measuring a 0.707107 VRMS sine wave at 50 Hz, showcasing its efficacy in precise AC waveform calibration.
... The basic functionality of the AC quantum voltmeter was already described in our last overview paper . Since then, several NMIs developed improved AC-QVM (Lee et al 2013, Rüfenacht et al 2013, Amagai et al 2018, Kim et al 2020. Depending on the PJVS array and its bias sourcecalled PJVS control unit in figure 12-and on the speed of the sampler, an AC-QVM covers voltages up to 10 V and frequencies up to a few kHz (see figure 15(c)). ...
60 years after the discovery of the Josephson effect, electrical DC voltage calibrations are routinely performed worldwide - mostly using automated Josephson voltage standards (JVS). Nevertheless, the field of electrical quantum voltage metrology is still propagating towards AC applications. In the past 10 years the fabrication of highly integrated arrays containing more than 50 000 or even 300 000 junctions has achieved a very robust level providing highly functional devices. Such reliable Josephson arrays are the basis for many novel applications mainly focussing on precision ac measurements for signal frequencies up to 500 kHz. Two versions of quantum AC standards are being employed. Programmable Josephson voltage standards (PJVS), based on series arrays divided into subarrays, reach amplitudes up to 20 V and usually are used as quantum voltage reference in measurement systems. Pulse driven arrays reach amplitudes up to 1 V or even 4 V and are typically used as Josephson arbitrary waveform synthesizers (JAWS). This paper summarizes the principal contributions from PTB to the present state of Josephson voltage standards with particular focus on developments for precision metrological applications and our proof-of-concept demonstrations.
... There has been significant interest in the use of JVSs to characterize the performance of digitizers, particularly for use in power measurements. Examples include the use of a PJVS to characterize the NI5922 digitizer [17], the 3458A [18][19][20][21][22] and the Fluke 8558A [23]. A Primary AC Power Standard based on a PJVS has been developed [24] and an ac power standard comparison with PJVS and JAWS has been undertaken [25]. ...
A method for traceability to SI for ac voltage and current based on high performance digitizers is presented. In contrast to the existing thermal-based methods, the proposed method utilizes direct traceability to quantum-based waveforms via the use of Josephson voltage systems. This allows not only a simplification of the traceability chain and reduced measurement times but also offers the potential for analysis of the ac voltage and current waveform spectral content, a feature which is not possible using thermal methods. Scaling of current and voltage is achieved by the use of current shunts and resistive voltage dividers respectively. Target operating ranges are up to 1 A and 100 V with a frequency range up to 1 kHz for both. The corresponding target uncertainty for this traceability route is 1 μVV ⁻¹ and 2 μAA ⁻¹ up to frequencies of 1 kHz. The traceability chain is described and various components are characterized to validate their suitability for this task. It is demonstrated that these uncertainty targets can be met under certain conditions. The use of multi-tone calibration waveforms is investigated to further reduce measurement time. An uncertainty analysis method based on simulation using real component performance data is demonstrated.
... To date, differential sampling of AC voltages [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] based on a programmable Josephson voltage standard (PJVS) has been mainly performed using an integrating sampler, Keysight 3458A (K3458A) 3 or a Δ-Σ analogue-to-digital converter, * Author to whom any correspondence should be addressed. 3 Disclaimer: certain commercial equipment, instruments, or materials are identified in this paper to adequately specify the environmental and experimental procedures. ...
... The magnitude of the error is determined by the transfer function of the filter, which is frequencydependent. For instance, for the K3458A, which is equipped with a low-pass filter with a bandwidth of 150 kHz in the DC voltage (DCV) mode, an error of approximately −25 μV V −1 is introduced for a 1 kHz AC waveform measurement [14,16]. For the NI5922 [17][18][19], although the finite impulse response filter of the sampler inevitably reduces the AC flatness of the passband, the contribution of the systematic error to differential sampling at frequencies up to several kilohertz is limited. ...
... Following each sampling measurement, the RMS amplitude, V 0 , of the reconstructed waveform was determined using discrete Fourier transformation analysis. To obtain the RMS amplitude of the original waveform V F , a digital-aperture correction [14] was applied to V 0 , ...
A high-precision sampler, Fluke 8588A multimeter in the sampling mode, was utilised to perform differential sampling of AC waveforms with a programmable Josephson voltage standard. The systematic error on the differential sampling, induced by the inherent voltage-response characteristics and built-in low-pass filter of the sampler, was estimated. Experimental results and numerical simulations revealed that the sampler could be used for reliable differential sampling of AC waveforms at frequencies up to several kilohertz, with an appropriate number of the voltage steps per the waveform period, when the input bandwidth was set to 3 MHz. In addition, the sampler was compared to an integrating sampler, Keysight 3458A, now widely used for differential sampling. At 62.5 Hz, a key frequency in the future on-site key comparison of the differential sampling on AC voltage, the difference in RMS-amplitude values obtained by the differential sampling using the two different samplers is approximately 150 nV/V due to the systematic error caused by the limited bandwidth of 150~kHz for the integrating sampler.
... Nowadays, such ac-QVMs have become commercial quantum-based ac voltage standard measurement systems that provide accuracies of about 1 μV V −1 up to frequencies of 2 kHz within minutes of measurement time [6] and are routinely operated at commercial calibration laboratories [7]. However, ac-QVMs are still the subject of investigations for different configurations [8], for Josephson comparisons [9], and especially onsite state of the art comparisons [10]. The full potential of the PTB ac-QVM (one part in 10 8 at 250 Hz) was demonstrated in a direct comparison with a 1 V pulse-driven Josephson system [11]. ...
Differential sampling relative to a Josephson waveform, the ac quantum voltmeter (ac-QVM), has been established as the most accurate method for measuring signals below 1 kHz with an uncertainty of 1 part in 10 ⁸ ( k = 1) for 1 V at 250 Hz. Commercial ac-QVMs provide accuracies of about 1 part in 10 ⁶ up to frequencies of 2 kHz. Here we present a new sub-sampling technique to extend the frequency range of an ac-QVM up to 100 kHz. The measurement results at 1 V RMS amplitude agree well within 5 µV V ⁻¹ ( k = 1) with the nominal voltage values for all frequencies from 500 Hz to 100 kHz. Two different analogue-to-digital converters are compared, sampling techniques, error sources and corrections as well as detailed uncertainty estimations are discussed.
... Fortunately, the chip could retrieve its best operating capabilities. As part of the collaboration with the KRISS [8], a new sampler was delivered to the laboratory and is expected to be implemented in the near future. Two computer-controlled low thermal electromotive force switches were developed in collaboration with the PTB. ...
In order to fulfil its mission to ensure and promote the global comparability of measurements, the BIPM operates laboratories in the fields of physical metrology, time, ionizing radiation and chemistry. These laboratories act as centres for scientific and technical collaboration between member states providing capabilities for international measurement comparisons on a shared cost basis. They coordinate international comparisons of national measurement standards agreed to be of the highest priority, and they establish and maintain appropriate reference standards for use as the basis of key international comparisons at the highest level and provide selected calibrations from them. The BIPM sustained all of its key activities throughout the periods of confinement resulting from the global pandemic in 2020 including: the publication of Circular T each month, the annual World Metrology Day celebrations and the launch of the new key comparison database (KCDB 2.0). Several activities were brought forward in the work programme including the automation of data handling in the International Reference System (SIR) for radionuclide metrology and on-line technical exchanges and capacity building initiatives. The BIPM has also worked to understand how best to support the National Metrology Institutes (NMIs) as a 'new normal' emerges. As a first step, the NMI 'COVID action' repository was implemented and two pilot studies were launched by the CCQM on the measurement of SARS-CoV-2 and SARS-CoV-2 antibodies. New ways have been developed to support the International Committee for Weights and Measures (CIPM) consultative committees on-line. For example, during 2020 a total of 70 video meetings were held for the CCQM, with similar trends for other CCs. In the following sections, we provide highlights of the work the laboratories have undertaken during 2020.
A system for ac–dc voltage transfer at ultra-low frequencies is established with a dual-heater thermal voltage converter (DHTVC) in this article. The system is based on the premise that the thermoelectric potential of the thermal voltage converter (TVC) is square related to the input voltages. The output thermoelectric potential is constant when two orthogonal and equal-amplitude sinusoidal signals are input to the DHTVC. How to evaluate and compensate for the key parameters that affect the stability of output thermoelectric potential is discussed in detail. In this article, a verification method is also proposed to prove the accuracy of the ac–dc transfer results at low frequencies based on quantum voltage technology. The high-precision digitizer PXI-5922 is introduced as the transfer standard. The ac–dc difference of sampling error is calibrated using ac–dc voltage transfer with DHTVC as the reference standard at low frequencies down to 0.1 Hz. The dc and ultra-low frequency errors are also calibrated by programmable Josephson voltage standard (PJVS). The uncertainties of calibration results from two different methods are evaluated, respectively. The calibration results from ac–dc voltage transfer with DHTVC and PJVS show good agreement and inconsistency is less than 5
$\mu \text{V}$
/V at frequency ranges from 10 down to 0.1 Hz.
