Cristian-Gyözö Haba, Liviu Breniuc
MICROCONTROLLER AND PROGRAMMABLE CIRCUIT-BASED DEVELOPMENT BOARDS USED IN DIGITAL INSTRUMENTATION LABORATORY

Congested curricula results in serious need to effectively and quickly teach digital design and its application to different areas of engineering. Digital instrumentation is one of these areas which has a very rapid development as more functionality of the measuring systems is migrated from analog to digital implementation. In our faculty we have organized a laboratory for teaching digital measurements and digital instrumentation using XESS development boards which have certain advantages such as: low cost, presence on-board of both microcontroller and programmable circuit, low cost development software for students (Xilinx Student Edition), easy downloading of configuration and program files for the programmable circuit and microcontroller respectively. These features, among which one of the most important is the possibility of reconfiguring logic, allowed us to organize a large set of laboratory sessions.

Giovanni Bucci, Edoardo Fiorucci, Carmine Landi
DISTRIBUTED MEASUREMENT STATION FOR THE EVALUATION OF THE IMPACT OF POWER ELECTRONIC EQUIPMENT ON THE POWER QUALITY OF ELECTRICAL DISTRIBUTION NETWORK

The quality of the electrical power supply is increasingly becoming a central topic of discussion. The interference sources in the mains are caused by electronic power control with non-linear components that are used more frequently (e.g. PCs and industrial systems with speed-controlled drives), also in domestic appliances (e.g. television sets, economy lamps). High order harmonics, voltage fluctuations and high frequency disturbances with slew-rates of some microseconds or less can be mentioned as examples. In some cases the frequency and width of these voltage variations can produce a physiological irritating phenomenon due to luminance fluctuations of the lighting (flicker effect). These electromagnetic disturbances can cover a large interval of frequencies and can be present in industrial, domestic as well as commercial systems. Therefore in the last years the monitoring of the quality of supply networks has become an issue of international interest. A low-cost distributed measurement system, which allows power supply quality to be monitored in large industrial environments, is then proposed in this work. The paper also goes on to discuss the problem of the characterization of the power monitoring systems, presenting the results obtained with our prototype.

Beata Palczynska, Ludwik Spiralski, Janusz Turczynski
THE NEW METHOD OF INTERFERENCE ASSESMENT IN LOW-VOLTAGE POWER SUPPLY LINES

The paper presents the interference model appearing in the low voltage supply in the form of series connection of equivalent sources: periodic and random. It gives the method to measure interference within low frequencies as well as high frequencies with the use of a typical measuring receiver with frequency change. The application of the measuring receiver makes it possible to limit the band of the analysed high frequency signal to the band equal to the width of intermediate frequency band of the measuring receiver. The receiver, in turn, enables further analogue-digital processing of the signal with an a/c converter of relatively low sampling frequency (of tens of kHz). The proposed method of interference measurement enables a deep analysis of the examined waveforms, especially the distinction of random and periodic components of interference. The paper presents the realisation of the interference measuring system and the exemplary results of the measurements carried out with the system.

D. Mirri, G. Pasini, P. A. Traverso, F. Filicori, G. Iuculano
A FINITE-MEMORY DISCRETE-TIME CONVOLUTION APPROACH FOR THE NON-LINEAR DYNAMIC MODELLING OF S/H-ADC DEVICES

A non-linear dynamic black-box model for Sample-Hold and Analog to Digital Conversion devices (S/H-ADC) is proposed in this paper. It derives from the expansion of a Volterra-like series previously introduced by authors and it is based on a discrete convolution in the time domain which describes the non-linear dynamics of the system. The model allows a functional description of the S/H-ADC non-linear behaviour as the sum of two blocks which take separately into account the static and the purelydynamic contributions. The model characterization can be carried out by means of a simple and reliable measurement procedure and the model analytical representation allows an easy implementation in the framework of commercial available CAD tools for circuit analysis and design. Preliminary experimental results which validate the proposed approach are presented in the paper, together with some examples which show model capabilities in predicting device behaviour under non-linear operating conditions.

Raul Land
EFFECTIVE ALGORITHMS FOR DYNAMIC QUALITY TESTS OF A/D CONVERTERS USING STEP-WISE APPROXIMATED MULTI-CYCLE SINE WAVE

When the step-wise approximated multi-cycle sine wave is used as the testing input signal for dynamic quality tests of the A/D converters, the effectiveness, accuracy, and the resolution of the chosen DFT analysis method depends on the proper choice of the method parameters. This paper deals with the theoretical problems of the analysis of the obtained output data of the A/D converter when the above mentioned input signal is applied. The basic principles of effective algorithms are outlined.