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Hüseyin Çaycı
APPLICATION OF DIGITAL SAMPLING METHOD FOR VOLTAGE TRANSFORMER TEST SET CALIBRATIONS

An application of digital sampling method for calibration of voltage transformer test sets is described. A digital sampling wattmeter with well-known operating principle was configured and used as a reference comparison bridge. Because of its high accurate ratio and phase error measurement capability, any type of test set regardless of their operating voltage ranges could be calibrated. In this paper, the accuracy of ratio error and phase displacement measurements of the sampling bridge is analyzed for nominal voltages with amplitude and phase differences up to 2% and 2 crad, respectively. Additionally, a simple automation method in generation and adjustment of ratio and phase error values is also described.

G. Betta, D. Capriglione, N. Pasquino
ASSESSMENT OF WORKERS’ EXPOSURE TO ELECTROMAGNETIC FIELDS GENERATED BY MAGNETIC RESONANCE IMAGING SYSTEMS

The paper presents the results of an experimental activity, focused on the estimation of electromagnetic fields generated by magnetic resonance imaging systems and carried out with the purpose of characterizing the exposure of workers to static, low frequency and radio frequency fields. This is an initial activity of a wider research plan that aims to: i) evaluate the dependence of the field strength on the magnet's technology and on the diagnostic protocol; ii) identify the most suitable procedures that allow a reliable measurements of the emissions generated by these systems; iii) assess the distance from the magnet at which exposure limits may be exceeded thus posing potential threats to workers’ health. For the case studied, the static magnetic field proved to follow the theoretical values only close to the magnet's bore due to the effect of the absorbing boundary conditions of the walls, with a few percent variation due to the operating conditions; the contribution in low frequency band is mainly determined by the 50 Hz magnetic field; and finally the radiofrequency band only has contributions from the diagnostic pulses at the resonance frequency, with exposure levels usually below the action limits.

Josef Vedral, Pavel Fexa, Jakub Svatoš
COMPARATIVE TESTING OF DYNAMIC PARAMETERS DACS WITH MULTI-TONE SIGNALS

In this paper is presented methods for testing dynamic parameters DA converters with Multi-Tone signals. Results of this test with discrete multi-tone signal and equivalent amplitudes, AM and FM signals compared with standard Single-Tone Fourier Transform Test.

René Harťanský, Mikuláš Bittera, Jozef Hallon, Peter Benkó
INCREASE OF CALIBRATED METER RANGE AT DISTANCE MEASUREMENT

In area of metrology there is often a necessity of microwave distance meter calibration. The calibration is executed by distance measuring from the microwave distance meter to conductive plane, of which distance is defined accurately (by means of micro-steps of step motor, which moves the plane or by means of the reference laser distance meter). Some disadvantages may appear at higher distances when accuracy of the measurement are affected by parasitic reflections of microwave radiation from walls of the room, in which calibration is executed. For example, if a flaring angle of the microwave distance meter is 23°, then the first reflection from the sidewall, at 1.5 m distance, occurs at 7 m and from the framework, at 1 m distance, at 4 m yet. Such a situation significantly affects execution of calibration at the distances more than 4 m. There is several manners how to solve such a problem.

Jan Dvořák, Jiří Novák
ROUTING ALGORITHM FOR POWER LINES

This paper presents new routing protocol designed for use in AMR and AMM systems using powerline communication (PLC) for data collecting and network control at their last mile. First part of the paper describes the AMR and AMM systems and the reasons for their implementation. Further the narrowb and powerline communication as relatively simple way for data transfers at the last mile is shown and briefly described. Power-line channel characteristic implies a need of a network layer protocol implemented in the PLC nodes for such large-scaled narrowband PLC networks. In the next part simple routing protocol algorithm based on minimal energy consumption is presented. Finally the paper describes simulation software used for protocol design and its functional validation. Power line channel model used in simulator is described in detail.

Antonio Cataliotti, Valentina Cosentino, Alessandro Lipari, Salvatore Nuccio
ON THE METHODOLOGIES FOR THE CALIBRATION OF STATIC ELECTRICITY METERS IN THE PRESENCE OF HARMONIC DISTORTION

This paper is focused on the problems related to the calibration of static electricity meters with nonsinusoidal test waveforms. This is an up-to-date issue since the harmonic distortion levels are ever increasing, especially in low-voltage power systems, and in such conditions the performances of the modern static electricity meters can be negatively affected, depending on the implemented measurement algorithm. Thus it is important to test the meters with nonsinusoidal waveforms. The paper analyzes the problems related to both the choice of the test signals to be used for calibration and the implemented metric, with a particular focus on the reactive energy meters. The analysis is supported by several experimental results.

Damir Ilid, Ivan Leniček, Luka Ferkovid
USE OF HIGH-RESOLUTION DIGITAL MULTIMETERS FOR THE CALIBRATION OF TEMPERATURE SENSORS

The calibration of precise negative temperature coefficient resistors (NTCRs), which have resistance RN = 10000 Ω at a temperature of 25 °C and limits of error ±0,2 °C in the range from 0 °C to 70 °C, by means of the reference platinum resistance thermometer Pt-25 (with the resistance of ≈ 25,5 Ω at 0 °C) in the range of (23 ± 4) °C, and the high-resolution digital multimeters (up to 8.5 digits), is described. The influence of the resolution of the digital multimeter is investigated, as well as the influence of the self-heating of NTCRs and the measurement on different ranges and with different currents during the comparison of different type of sensors. The analysis of the resistance-versus-temperature (R - T) dependence is done by using the least-squares method and the two-parameter approximation curve for NTCRs. The results have shown that, in the range of (23 ± 4) °C, which is useful for the laboratory applications, NTCRs can be calibrated by means of Pt-25 thermometer and high-resolution digital multimeters with an uncertainty of a few millikelvin, which is very convenient for their wide application as precise and sensitive temperature sensors.

Jan Breuer, Jan Fischer, Jaroslav Roztočil
COMPARISON OF IEEE 1588 IMPLEMENTATIONS USING THE STM32 CONNECTIVITY LINE PROCESOR

In distributed system containing multiple clocks, precision time synchronization can by achieved using IEEE 1588 protocol. This paper presents a hardware assisted and a software implementation using the STM32 Connectivity Line (STM32C) processor. Accuracy of time synchronization depends on stability of master and slave oscillators, timestamping technique and reference clock adjustment capabilities. Allan deviation of both master and slave are measured to determine oscillator stability. Several tests using a hardware and software timestamping are made. Synchronization performance is also tested using an internal reference clock and using internal general purpose timers/counters.

Ľuboš Ovseník, Anna Kažimírová Kolesárová, Ján Turán
A SYSTEM FOR VIDEO SURVEILLANCE

More than ever before, it is important to maintain the safety and security of citizens, public infrastructure, buildings. This paper is concerned with video surveillance systems. With the growing quantity of security video, it becomes vital that video surveillance system be able to support security personnel in monitoring and tracking activities. In this paper is described new video surveillance system.

Martin Fifik, Ján Turán, Ľuboš Ovseník
TRAFFIC SIGNS RECOGNITION EXPERIMENTS WITH TRANSFORM BASED TRAFFIC SIGN RECOGNITION SYSTEM

This paper describes tests on transform based traffic sign recognition system. Traffics sign recognition subsystems: preprocessing, projection transform stage, and classification are outlined. Results of traffic sign detection and recognition from real image taken from Slovak roads are shown and discussed.

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