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A calibration system of a 3.5 mm coaxial power sensor was implemented using transfer standards with 7 mm coaxial or K-band waveguide input connectors. A 7 mm-3.5 mm or WR42-3.5 mm adapter was used to form a combined transfer standard. The effective efficiency of the combined transfer standard was obtained. The 3.5 mm coaxial power sensor was calibrated using the well-known direct comparison method...
The present status of an international attempt of several national metrology institutes to determine the Avogadro constant with a relative standard uncertainty better than 2ldr10-8 is presented. To this end, a world-wide collaboration has been set up to produce a 5 kg 28Si single crystal with an enrichment factor greater than 99.985%. Technological steps for the growth of the 28Si single crystal,...
A new calibration system for automated high-voltage current-comparator-based capacitance and dissipation factor bridges is presented. It does not require synchronization circuits between the digitizers and the generators. It is possible to simulate 1:1 capacitance ratio and dissipation factors from 1.10-6 with standard uncertainties of less than to 1.10-1 with standard uncertainties of less than 1...
Calculating the force on a reference mass for the electronic kilogram experiment requires using both absolute and relative gravity meters to measure the acceleration of gravity. Tests have been conducted to achieve an uncertainty of less than 1 part in 108.
For high precision impedance measurement only a very limited range of commercial instruments is available. The most accurate commercially available instruments for impedance measurements are capacitance bridges. Precise instruments for inductance or general impedance measurements are not available on the market. This paper describes novel methods for calibration of inductance reference standards from...
The Teflon frame is used in establishing NIM's AC Resistance Calculable Standard. Comparison with the suspended design such as coaxial, quadrifilar and octofilar types, the frame of resistor gives better stability. However, the dielectric loss of Teflon frame will bring additional ac/dc difference. To measure this dielectric loss precisely, a new measurement structure is provided and the substitute...
A switching device with low thermal electromotive forces is a core apparatus in all voltage standard laboratories where the unit must be maintained with high accuracy. Switching is essential in the pair intercomparison measurements required to maintain a voltage standard with multiple references and for the dissemination of the unit. Although various low- thermal switching equipment are available...
In this paper, the uncertainty of the QHR standard system at NIM is estimated and the combined standard uncertainty is given out. A new method to calibrate CCC ratio unit working in-situ is introduced.
A self-calibrating current transformer with nominal ratio 10 A to 100 mA, intended for low frequencies applications, was developed. It has 100 independent primary windings to be connected in series or parallel, so that it can be configured as 100:1 or 1:1 transformer (all windings in series). This last ratio permits autocalibration. Error sources are analyzed, and it is shown that differences between...
An intercomparison of calibration systems for instrument transformers between Korea Research Institute of Standards and Science (KRISS) and National Research Council of Canada (NRC) with many different ratios at 60 Hz was performed using six portable transfer standards consisting of two current transformers (CTs) with current ratios of 5 A/5 A up to 20,000 A/5 A and four voltage transformers (VTs)...
The NIST electronic kilogram has had three published results with successively smaller uncertainties. In the present design, there are several measurement components that have uncertainties that are difficult to reduce further. These limiting uncertainties are discussed.
We have measured Newton's gravitational constant with a commercially available mass comparator. In this experiment, the difference of the gravitational force of 13,600 kg mercury on two 1.1 kg copper masses was measured with a relative statistical uncertainty of 16.3times10-6. Including the systematic uncertainties we determine the gravitational constant G to be 6.674 252(122)times10-11 m3kg-1s-2.
A novel, self-consistent approach for the determination of the correction factor of a waveguide microcalorimeter is described. The method is based on the measurement of offset shorts of different length followed by one single calibration measurement of an unknown thermistor DUT. Without precisely measuring the RF power incident to the reference plane, both calibration factor of the DUT as well as...
The problems of transfer Quantum Hall resistance to 1 Omega resistance standard with direct current comparator bridge (DCC) are introduced. Some effective technique ways are suggested by analyzing the possible causations of the measurement results' fluctuation. The comparing experiments between DCC and cryogenic current comparator bridge (CCC) have been performed with analyzing the uncertainty of...
The ISO GUM provides a framework for uncertainty evaluation using the law of propagation of uncertainty (GUF). The output quantity is characterized by a Gaussian or student-t distribution. Supplement one to the GUM deals with the propagation of probability distributions of the input quantities of a mathematical model of measurement for the evaluation of uncertainty by a Monte Carlo method. This paper...
This paper describes the design and verification of current shunts for AC-DC transfer measurements in the range 20 A to 100 A. The measured AC-DC current transfer difference of the 100 A shunt is -36 muA/A at 100 kHz with an uncertainty of 200 muA/A.
Published RF and microwave data on dielectric reference liquids [NPL Report CETM33] are reassessed to allow quoted measurement uncertainties to be reduced. The aim is to make the data maximally useful to users. The modelling approach followed should have application beyond dielectric metrology.
For the 7-term SOLR calibration method to calibrate a four-sampler vector network analyser (VNA), the deviations of the seven error terms, as well as of the the measured S-parameters are determined due to the deviations of the reflections of the calibration elements (Short, Open and Load) from their true values. For the SOLR calibration, a reciprocal unknown network is used instead of a known Through...
A number of direct comparisons of Josephson Array Voltage Standards (JAVS) using Superconductor-Insulator-Superconductor (SIS) junction arrays have been performed at the National Metrology Centre (NMC), Singapore. The comparisons were performed over a range of voltage from 1 V to 10 V and with different combinations of array chips, both USA and German made. The comparisons used a parallel biasing...
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