Vladimir Haasz, Jiri Kalina, Milan Komarek, David Slepicka, Petr Suchanek
Extension of the Test System for Middle-Resolution Digitisers up to 20 MHz

The system for testing of digitisers at the frequency of input signal of 1 MHz designed and manufactured at the Dept. of Measurement in the last years was extended for the frequencies up to 20 MHz. Sets of common LC filters (both band pass and band stop) for frequencies 4.4, 9.5 and 19.5 MHz were developed. First experiments showed that these low-cost LC filters based on coils with ferromagnetic cores are sufficient for direct testing of digitisers with ENOB < 14 at a frequency of the test signal up to 10 MHz and for digitisers with ENOB < 12 up to 20 MHz.

P.A. Traverso, G. Pasini, A. Raffo, D. Mirri, G. Iuculano, F. Filicori
Characterization and Compensation of Dynamic Non-Linearities in Digital Data Acquisition Channels by Means of the Discrete-Time Convolution Model

A technology-independent, behavioural non-linear dynamic model, which has been previously proposed by the authors for the accurate experimental characterization of digital acquisition channels, is considered in this paper for the compensation of the overall non-idealities within these measurement subsystems. It is shown how the non-linear dynamic equations of the model, which inherently describe both the static and the dynamic non-linearities affecting the channel, can be numerically inverted, allowing for the reconstruction of the spectrum at the input of the system from the corrupted samples available at its output. Different recursive algorithms for the solution of the non-linear problem involved into the procedure proposed are described. The choice among these can be accomplished according to the applicationdependent best trade-off between numerical convergence robustness and computational cost. Experimental results are provided, which validate the technique proposed.

Krzysztof Duda, Andrzej Bień
Real-time detection of transient disturbances in electric power network

In this paper we present real-time application for detecting, extracting and automatic classification of transient disturbances in electric power network. Proposed method was implemented on Texas Instruments C6713 DSK toolkit and tested with both laboratory-generated and real-world power network signals with good results. For each detected transient a set of parameters is evaluated including the time of occurrence, duration time, energy and frequency spectrum. Classification of disturbance can relay on arbitrary combination of those parameters (e.g. one can be interested in finding disturbances with sufficiently high energy and specified duration time). The presented implementation was design to be a part of complex system for Power Quality (PQ) monitoring.

Alexandru Salceanu, Valeriu David, Mihai Cretu
Prolongation of Double RLC Model for ESD Manifold Events

The starting point of our work was focused around some phenomena encountered while testing the ESD immunity of vehicle electrical equipment, mainly using a laptop, an ESD gun and a scope. One target of our approach is to find explanations for the influence of the position of the ground connection of the ESD tester and of the rod geometry and dimension upon the rise time of the injected current into the abovementioned laptop. The scope was a good 500MHz one, with connectivity facilities, inserted in an experimental set-up recommended by IEC. The second target was to extend a model and to set its lumped elements for multiple discharges. We observed during some ESD events, successive pulses, with a decreasing energy level, being separated by a time period lasting tens of milliseconds. We consider that this multiple discharge event could by modelled by up-grading the body metallic model. Scope-tracing many ESD discharge waveforms, we determined the values of the elements from a double RLC scheme with two ground connections, forming self-oscillating circuits with variable attenuation, for allowing the extension from a single discharge pulse to multiple ones.

Tomasz Tarasiuk
Estimation of Measurement Window Width by Interpolation Based on Wavelet Coefficients – Case Study

This paper deals with the problem of reliable width estimation of measurement window. The simple method is detection of zero-crossing moment of given signal by analysis of sample polarisation changes. But the method is sensitive to waveform distortions, especially analysed signal multiple zero-crossings. So, the idea of implementing discrete wavelet transform for risk reduction of measurement results corruption by the higher frequency phenomena has been proposed and preliminary tested [1]. In this paper, the concept has been further developed, especially the analysis of real voltage with multiple zero-crossing has been carried out.