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We have investigated the performance of a method called the Reference Step Method at low voltage levels. The method has been evaluated earlier at voltage levels from 0.1 V to 1 kV with excellent results. The advantages of this method are that it uses commonly available equipment and can be fully automated. We have made comparisons with three other low-voltage methods and the differences show that...
The AC-DC difference of an AC-DC transfer standard varies with its input voltage and ac frequencies. Its calibration may not necessarily cover all the voltage-frequency points for their possible uses in practice. This results in situations when there is no reference value to use such a transfer standard for calibrations at some voltage-frequency points. This paper analyses the principle structure...
This paper describes the principle, structure and the self-calibration method of a new type of current comparator which is designed and constructed by NIM. This current comparator is based on “shield guiding structure”, and its ratio is from 0.1∶1 to 1∶1.
This paper introduces a calibration method for measuring the Miniature Current Transformer (MCT) which is based on sampling technology. In this way, we can measure the miniature current transformer with secondary current from 1mA to 100mA and different load accurately.
Owing to their uttermost linearity, high-grade multimeters can be profitably used as voltage ratio standards. To exploit the high performances achievable, the residual nonlinearities must be evaluated with a quantum reference and particular attention is required to avoid reduction in accuracy. Differently from the resistive divider case, the ratio is obtained from actual voltage measurements, and...
A sampling current ratio bridge has been developed, tested and validated for the accurate complex ratio measurement of AC current transducers for primary currents up to 10 kA with expanded uncertainties of 5 · 10−6 in magnitude and 5 µrad in phase (k = 2). A unique property of the system is the use of digitizers for sampling of the secondary current signals and step-down transformers with a large...
The paper describes frequency dependence correction of the Agilent 3458A DMM in DCV sampling mode. The biggest error source identified is the input filter roll-off, which was measured and evaluated with an asynchronous sampling technique using phase sensitive sine fit algorithm. Corrected response is flat within 50 µV/V in the whole audio frequency band.
This paper describes the development of a compact inductive voltage divider (IVD) setup and its calibration in the frequency range between 1 kHz and 100 kHz and voltages up to 5V. The desired frequency and uncertainty range requires a two-stage IVD design with coaxial windings, a triaxial differential branch, and voltage controlled shields to minimize capacitive stray currents and the corresponding...
An error vector magnitude (EVM) measurement method for W-CDMA source is proposed using a real time oscilloscope with traceability to SI unit. Also measurement uncertainty is evaluated based on a Monte-Carlo simulation, which takes into account the errors from the oscilloscope and signal processing. The measured EVM of a source at 900 MHz is 0.2535% ± 0.0057% at 95% confidence level.
This paper describes an automated high-accuracy impedance bridge for the comparison of resistors, inductors or capacitors in the range between 1 mΩ and 100 MΩ over a frequency range of 10 Hz to 20 kHz. The bridge consists of a high resolution digitizer and a six-channel digital waveform generator. A solid state multiplexer has been made to switch between the various positions in the bridge and to...
An improved two terminal-pair coaxial AC bridge with auto source balance is constructed at NIM for high precision capacitance measurement. The errors introduced by auto source balance in the bridge are at negligible level. The bridge can disseminate the calculable capacitance to 1 pF, and transmit capacitance from 1 pF to 10000 pF. A minimum standard uncertainty 7.7 × 10−9 is achieved at 1592 Hz.
We present the comparison of results from the generation and the measurement of direct currents in the pA range, performed with traceable state-of-the-art methods at highest accuracy. The currents were generated with the capacitor charging method, and measured with the first prototype of a novel picoammeter developed at PTB. The results confirm the agreement between both methods and the linearity...
Instrument current transformer burdens must be checked and calibrated before use in the current transformer calibrations. Common difficulty in the measurement of current transformer burdens is the requirement of a laboratory type test setup with non-commercial devices. A new technique has been developed to eliminate this problem and to make the measurements directly with a commercial wattmeter and...
This paper describes two methods of electric charge calibration, one based on capacitors and a voltage source, another in a commercial current source. They were compared, and good agreement was found. Strengths and weakness of the two methods are remarked.
A 10 V programmable Josephson voltage standard system has been installed at the National Research Council Canada. The current margins for the first Josephson step at either current polarity are greater than 1 mA. A preliminary direct comparison of this programmable system with a hysteretic Josephson voltage standard is performed at 10 V.
This paper describes the diagnostic measurements involved while performing impulse tests. For most applications during impulse tests, the impulse voltage and impulse current are measured. Because of the nature of impulse test it is very common that Electro Magnetic Interference signals (EMI) are generated. This EMI will influence the measurement results. Therefore these tests are done in a well-shielded...
This paper describes an experimental evaluation of a high precision voltage harmonic analyzer at power frequency under square waveform. The error and uncertainty of the signal generator were calculated to use it as a harmonic reference standard at UTE (Uruguayan designated National Metrology Institute).
The expanded measurement uncertainty of both the measurement of radiated emission and the measurement of electromagnetic field immunity depends mostly on the field distribution within the testing volume. In general, that uncertainty contribution has to be estimated from sampled measurement data. In most cases this results in an overestimation. The estimate can be reduced by exact knowledge of the...
This paper describes calibration methods of current comparators (CCs) and balancing current generators (BCGs) accompanied with them, for establishing a high-accuracy ac current ratio standard up to 4 kHz. The CC calibration is explained mathematically according to the self-calibration procedure that NMIJ has been exploiting. The BCG calibration is based on measurement of the conversion ratio. The...
This paper presents a direct comparison of two time transfer techniques on independently calibrated links: Time Transfer by Laser Link (T2L2) and Global Positioning System (GPS) satellite common-views (CV). The two different techniques are described, along with the independent link calibrations. The results achieved during one measurement campaign involving three European laboratories are presented,...
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