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Page 794 of 977 Results 7931 - 7940 of 9762

Jaroslav Boháček
FREQUENCY PERFORMANCE OF HAMON TRANSFER STANDARDS

Shielded and temperature controlled 1 000 Ω / 10 Ω and 10 000 Ω / 100 Ω transfer standards have been realized to be used in the frequency range up to 5 kHz. Their frequency performances have been evaluated by comparison with calculable resistors of quadrifilar and octofilar design. Thanks to the known frequency performances, both standards can serve as reference devices for precision AC measurements of resistance ratios made by means of commercial four terminal-pair bridges.

Zygmunt Kusmierek, M. Jerzy Korczynski
MEASUREMENT OF ELECTRICAL ENERGY UNDER NON-SINUSOIDAL VOLTAGE AND CURRENT - CONDITIONS AND REQUIREMENTS

The main purpose of the paper is to present the metrological aspects of virtual kilo-watt-hours meters developed for measurement of active power in while voltage and current are non-sinusoidal. Today’s electrical kilo-watt-hours meters are built as devices for sinusoidal signals both for current and voltage. These electromechanical units are not appropriate for distorted signals, so the new generation of kilo-watt-hours with a used of electronic elements are under development. Deliberation of virtual active electronic electrical power meters are presented here.

M. J. Korczynski, A. Hetman
CALCULATION OF EXPANDED UNCERTAINTIES WITHOUT KNOWLEDGE OF COVERAGE FACTOR

The main purpose of the paper is to present a new fully deterministic, numerical approach to calculation of coverage interval at certain coverage confidence. The main crucial aspects for this method are revealed and the accuracy of this method is presented as well. A brief comparison to others methods, analytical and numerical based on Monte Carlo methods and also so widely applied and recommended in GUM law of propagation of uncertainties are described. Several examples are presented.

Gaetano Iuculano, Gabriella Pellegrini, Andrea Zanobini
EVALUATION OF MEASUREMENT UNCERTAINTY USING BAYESIAN INFERENCE

The Bayesian inference provide a natural and consistent way to make best use of all relevant historical information which characterizes the measurand in a measurement process. In this paper the use of Bayesian method is described to include prior information in the evaluation of the measurement uncertainty. The proposed approach gives an implementation on the evaluation of the confidence region with respect the usual techniques described in the ISO Guide to the Expression of Uncertainty in Measurement (GUM). Experimental model is studied and numerical results are reported to assess the validity of the proposed formulae.

Lech Hasse, Krzysztof Rogala, Ludwik Spiralski, Janusz Turczyński
FACTORS DETERMINING THE PRODUCTION TESTING OF HIGH RELIABILITY INTERFERENCE SUPPRESSOR CAPACITORS

Non-linearity and noise properties of a capacitor have been established as criteria for selection of interference suppressor capacitors for different reliability classes. It can improve the process of quality estimation of high reliability capacitors. The implementation of techniques for non-linearity and noise measurements in the system for production testing of high reliability interference suppressor capacitors is described. Selected experimental results of measurements for capacitors produced by MIFLEX have been presented.

Grzegorz Lentka, Marek Niedostatkiewicz
THE GOERTZEL FILTER-BANK USAGE IN THE NON-STATIONARY IMPEDANCE MEASUREMENT

The paper presents the method of measurement of non-stationary impedance parameters based on measurement signals sampling and DSP. The Goertzel filter-bank approach has been proposed and analysed. The proposed method has been compared to traditional STDFT approach. The results of simulations and experiments have been presented.

Emil Farkas, Iuliu Szekely
RELATIVE CALIBRATION OF INERTIAL SEISMOMETERS

This paper discusses technical problems of performing an accurate electrical sine-wave calibration of seismograph systems. This topic is well known in the seismic scientific community, however it has been presented to a lesser extent to engineering research and industrial circles. The purpose of the paper is to identify the unsolved technical questions related with calibration of seismograph systems. Finding exact solutions is beyond the purpose of this paper, considering the complexity of research and design work required.

Claudio Narduzzi, Paolo Attilio Pegoraro, Luigi Prigol
SPECTRUM ANALYSER MONITORING OF WIRELESS COMMUNICATIONS NETWORKS

The paper presents an innovative approach to the monitoring of the RF power transmitted by a mobile base station, by means of a spectrum analyser. Results account for the statistical nature of the signals, providing the means to evaluate in a more realistic way the exposition to RF fields.

Domenico Luca Carnì, Domenico Grimaldi
PHASE NOISE MEASUREMENT IN SINGLE CARRIER DIGITAL MODULATIONS

The paper shows a new algorithm for the phase noise measurement. The algorithm is based on the constellation examination of the IQ plane of the single carried digital modulated signal. It can be used to measure the phase noise both on the carrier signal and on the demodulated signal. Advantages of the proposed algorithm are: (i) the number of samples in practice does not affects the error, (ii) the percentage error is reduced if compared with other methods, and (iii) the phase noise shape weakly affects the error. The paper provides the theoretical background and reports the results of numerical experiments that validate the proposed algorithm.

Domenico Luca Carnì, Domenico Grimaldi
ANN BASED DEMODULATOR FOR UMTS SIGNAL MEASUREMENTS

The paper proposes the use of the Artificial Neural Network (ANN) to design a new demodulator of the telecommunication signals. This demodulator is candidate to be employed into the measurement instrument of the third generation mobile telecommunications UMTS Terrestrial Radio Access. It is developed on the basis of the multiplayer perceptron ANN and it permits to perform in one shot both the descrambling and the despreading operations. Numerical tests performed by using signals according to the UMTS standard show that the ANN demodulator can guaranty greater accuracy than the traditional one in the case the modulated signal is affected by high level of both noise and distortion.

Page 794 of 977 Results 7931 - 7940 of 9762