The main advantages of the Rogowski coils are the Potential free measurement and the low cost compared to shunt and CT measuring systems. Usually they are applied for measuring high-amplitude or high frequency currents. The aims of the paper is to investigate a new analog signal processing able to overcome the major limitations of the Rogowski coils in low current and lowfrequency range.

Error analysis of a resistive sensor-to-microcontroller interface based on pulse width modulation (PWM) and time ratio measurement (sensor resistance over reference resistor), shows that leads resistance produce zero, gain, and nonlinearity errors. Because at the calibration points these errors are nulled out, several calibration resistors selected according to the sensor resistance range would reduce those errors in the full range. Two-point calibration and time ratio measurement yield errors smaller than 1 W for lead resistance of 10.5 W and sensor resistance from about 600 W to 3550 W, which is the typical variation range for a PT1000 temperature sensor.

The work reports the measurements of the excess-noise coming from the thick-film piezo-resistors (TFRs) deposited on metallic substrates. The purpose of this paper is to single out the best combination of conductive, dielectric and piezoresistive inks in order to minimise the electronic noise. At this purpose a comparison between the excess noise measurements made of the same inks and geometric characteristics but screen printed and fired on alumina substrates, are reported. Moreover, the article gives a description of the measurement instrumentation used and, in particular, of the low noise preamplifiers.

A new concept of distributed data acquisition systems using Java architecture is proposed. A connection of external modules (standard library for National Instruments DAQ board) to source code in Java is described. Next, an example of the system, that uses a communication based on sockets for remote monitoring of meteorological parameters, also via Internet, is presented.

Stability of root mean square (rms) voltage is one of more important parameters of electrical energy quality. To evaluate the stability - rather unstability of rms voltage- we use a flickermeter which determine the flickering severity factor P_ST. Flickermeter is such an instrument in which reaction of electrical power is modelled by source of light onto human psychophysical features. The obtained signal is statistically analysed. As a result we obtain value P_ST which is a measure of electrical energy quality. After statistical treatment of the signal we obtain the value of parameter P_ST which is a measure of electrical energy quality.
Functional of signal swing instead of statistical treatment is suggested to measure unstability of model signal. Functional of signal swing can be used for determined signals e.g. test signals, changes appearing in isolated cases (unit number of appearances in a certain time interval) and signals with statistical properties.The feature enables better interpretation of measuring results. The results obtained by a signal swing functional have properties similar to P_ST.