In a given summary the alternate voltage standard, which works over the voltage range from 0,1 V to 1000 V and the frequency range from 10 Hz to 30 MHz is presented. In the paper its structure and the main scientific and technical advancements are considered.

Comparison and unit transfer of the impedance parameter is provided using a lot of different very complicate manual bridges with numerous different standards. The main world-renowned laboratories (BIPM, NIST, NML, NPL, PTB, VNIIM, etc) in developed countries have their own primary standards, based on the Calculable Capacitor and appropriate transformer bridges, on the Quantum Hall Resistance and appropriate bridges and very accurate quadrature bridges for comparison of different impedance parameters, having original constructions. All these bridges constitute a very complicate set of devices that have long and intricate balance processes. In addition, these bridges and standards are divided into different sets and are disposed in various laboratories. The process of calibration and traceability is, therefore, complicate and very expensive. The project (No 2244, Science and Technology Center in Ukraine, see site www.stcu.int) supported by the USA and the EU, was aimed to create the set of accurate automatic bridges-comparators and the set of thermostated intermediary standards for impedance units traceability and reproduction. Here we show the results of the implementation of this project.

This paperwork presents the design and test of a microcontroller-based ECG (electrocardiogram) simulator. The ECG simulator is capable of generating nine ECG signals and a calibrated square wave (1 Hz, 1 mV at Lead II). The synthesized signals are: normal sinus rhythm (60 beats per minute – BPM, and 90 BPM), sinus bradycardia (30 BPM), sinus tachycardia (120, 180 and 240 BPM), sinus rhythm with tall T wave (6EC0 BPM), ventricular tachycardia (120 BPM), and a rhythm for asynchronous ventricular pacemaker (60 BPM). The simulated ECG signals can have their amplitudes continuously varied from zero to 2 mV at lead II, through a panel potentiometer, whose knob position does not affect the amplitude of the square wave calibrated signal. The technique used to synthesize the ECG signals, a modified direct digital synthesis (DDS), appeared superior in permitting the generation of signals of very good quality and yet using a relatively small amount of memory. This latter feature enabled the use of a simple 8-bit microcontroller together with an external precision D/A converter and a 2-pole lowpass active filter. The designed ECG simulator can be a handsome instrument to daily ECG machine test, maintenance and demonstration by hospital personnel and medical equipment maintenance groups and shops.

Detailed herein is the procedure to perform the calibration of a marine observation instrument, in this case a CTD, within the parameters of temperature, pressure and conductivity. It includes a calibration demonstration of the temperature and the pressure parameters.

This paper presents the results of two years of operation of an automatic system that compensates drifts of a rubidium atomic clock. This clock is the base of the Uruguayan National Time-Frequency Standard.