This paper presents an efficient design of a decimation filter for a continuous-time (CT) complex bandpass ΔΣ modulator in wideband-standards receiver. The RF front-end has been based on a modified low-IF architecture and the full receiver dynamic range is converted into the digital domain. The approach proposed investigates a new decimation process and realizes new functionalities such as image rejection and frequency down conversion IF/DC by a complex mixing on ΣΔ modulator bit stream. Two wide standards (IEEE 802.11a and 802.16) were chosen for design procedure illustration. The decimation structure was implemented on FPGA component using optimization techniques. Experimental results show the highspeed data rate and low-power consumption features of the proposed design.

This paper describes a system, which enables quantitative monitoring and evaluation of the influence of a pulse magnetic field on a live organism by using of bioimpedance measurement. Electric impedance of tissue varies according to the amount of blood contained in a segment at a given instant. Because blood has greater conductivity than tissue, the presence of a slightly increased amount of blood decreases the impedance of the tissue. The magneto-therapeutic instrument uses a couple of Helmholtz coils as the applicator. The magnetic field strength is approximately 60 mT. The current of these coils is controlled by the pseudo random impulse signal by using of a power switch. The random exciting generator was designed as a 16-bits generator of a Galois code. The bioimpedance has been measured by four electrode method by using of RF narrow band vector bioimpedance meter on the forearm. During the magnetic field exposure the bioimpedance signal level increases above the normal and its level reaches the maximum after about 10 minutes. The maximum value is approximately 50 % higher than the normal level.

In this paper, metrological infrastructure of Macedonia and Croatia will be presented in general, but more speciffically for measurement of high voltages and currents. As two countries become independent almost 20 years ago, they embarked on a similar metrological path, earning to strenghten international ties, to get more involved in organizations such as Euromet, to receive accreditation for the national measurement institutes, etc. However, as the two countries have emerging economies, it is sometimes difficult to develop all the necessary measurement methods, especially methods that need a lot of time and money to invest in, but are used very rarely. A work on two different measurement methods in our countries will be presented: a Rogowski coil (RC) being developed in Croatia and the current measurement unit (CMU) of a 20 kV combined current-voltage intrument transformer (CCVIT) in Macedonia.

Monitoring, control and management of modern electric power systems require more and more extensively the use of distributed measurement systems capable of providing accurate data from remote measurement stations located in the network nodes. Synchronization between the acquisition devices is one of the most critical tasks in designing such systems, since in many cases the practical usability of the measured data strictly depends on how accurate the time reference used in the remote stations is. When highly accurate time synchronization is needed, satellite systems, like GPS, can be used to provide the required time reference. Given that equipping every measurement station with appropriate GPS receivers can result in excessive costs, in this paper the possibility of using Precision Time Protocol (defined in the Standard IEEE 1588) to disseminate the time reference provided by the GPS in an electric subsystem is investigated. Experimental results will be provided to evaluate the performance achievable with this solution in one of the most challenging measurement problems, that is represented by the measurement of synchrophasors.

The main subject of authors’ research are non-contact methods of glass breaks detection based on analysis of acoustic signal generated during phenomena. Problem has essential meaning for modern, cost effective alarm systems, particularly installed into big buildings. Signal has stochastic character and the main difficulty of the problem is variability of many parameters (e.g. size and thickness of glass pane, distance from window to detector) and big amount of false signals (mainly accidental glass hits without break). Authors developed detection algorithm which uses Wavelet Transformation and few selected measures for signal features extraction and classification. Obtained detection efficiency >90% is satisfactory, but resistance to false signals (near to 80%) does not fulfill assumed level. Because the Wavelet Packet Decomposition allows more detailed analysis in frequency domain than WT, it is more suitable for extraction of time-frequency interdependencies in analyzed signals. This paper discuss some methods and results of WPD application and wavelet selection for improving system performance, and increasing the resistance to false signals.