Ryszard Roskosz, Michal Ziólko
MEASUREMENT ACCURACY OF SHORT-CIRCUIT LOOP IMPEDANCE IN POWER SYSTEMS

This paper presents the problems relating to the measurement of power system loop impedance in present day low voltage networks particularly in presence of voltage disturbances. The paper discusses the main sources of loop impedance measurement errors such as: the difference in impedances arguments, transients in tested circuit and the distortion of the voltage waveform in the measurement point. The conditions how to minimize measurement inaccuracy are also given. Example of loop impedance measurement errors are presented in the form of graves for different parameters of the tested circuit.

Tomasz Tarasiuk
INTERPOLATION BASED ON WAVELET COEFFICIENTS FOR FREQUENCY MEASUREMENT

Presented paper concerns the problem of signal period estimation improvement by means of the wavelet coefficients. In particular, the interpolation based on the wavelet coefficient has been proposed for this aim. The method does not require virtually any additional computational power of measurement device, under assumption that the wavelet transform has been implemented for waveform analysis. In the paper results of experimental research have been presented and its merits as well as shortcomings have been discussed.

Janusz M. Mosakowski, Andrzej Podgórski
IMPLEMENTATION OF 1/1 OCTAVE AND 1/3 OCTAVE FILTERS IN DIGITAL SIGNAL PROCESSOR

Set of filters is required for the analysis of sound and vibration signals usually composed of different elements. The designing process of so-called 1/1 octave and 1/3 octave digital filters and their implementation in the digital signal processor, working in the real time system, is shortly presented. The obtained exemplary frequency characteristics are given.

José Carlos Oliveira, Diamantino Silva Freitas, Artur Capelo Cardoso
ELECTRONIC CIRCUITS PARAMETRIC MEASUREMENT: A NEW APPROACH IN ELECTRICAL METROLOGY

The measurement of electrical quantities in electronic circuits is inscribed in the non-parametric world for a long time. Multimeters, Oscilloscope and Network Analysers are the preferred tools used by engineers. Parametric identification allows a new step in circuit characterization. This approach opens new perspectives in the process of electronic circuit’s design. The present paper presents a solution to the problem of parametric characterization. To allow the simulation and validation of the results a new simulation tool is also presented. The proposed simulation solution uses modified off-the-shelf standard software packages, integrates them closely, offering an expeditious way of bringing mathematical postprocessing power to a standard electronic simulation package, in the framework of circuit design and characterization or measurement.

Petar Knezevic, Vedran Srsen, Kresimir Segaric
ANALYSIS OF SOME QUALITY OF SERVICE PARAMETERS' IMPACT ON END-TO-END DELAY MEASUREMENTS IN VOIP NETWORK

Internet users and Internet service providers are using all kinds of tools for monitoring the communication network. Most of the measurements are done by inserting simulated traffic into the network and observing network performances. When used to measure some time-sensitive applications, like Voice over IP (VoIP), these tools in coherence with some network configuration techniques can result with inaccurate measurement result. We discuss some of those configuration techniques and their influence on delay measurements, and introduce possible solutions.