2005/2

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    Geometric Algorithm for Received Signal Strength Based Mobile Positioning
    (Společnost pro radioelektronické inženýrství, 2005-06) Brida, Peter; Cepel, Peter; Duha, Jan
    Mobile positioning is one of the fastest growing areas for the development of new technologies, services and applications. This paper describes a simple and efficient geometric algorithm using received signal strength measurements extracted from at least three base stations. This method is compared with standard Least Squares method. The simulation results show, that geometric algorithm gives more accurately location estimation than LS algorithm in multipath propagation.
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    Improvement in the Method for Bias Drift Compensation in Micromechanical Gyroscopes
    (Společnost pro radioelektronické inženýrství, 2005-06) Arnaudov, Rumen; Angelov, Yasen
    In this paper an improvement in method is proposed for the compensation of the bias drift in micromechanical gyroscopes by a change in the sign of the measured quantity. A general model of external factors of influence is proposed that must be taken into account when the method is applied. An information-measurement system is developed and experimental data are taken from two commercial sensors. The derived results are showing considerable improvement in the long-term bias stability when the proposed improvement in method is applied.
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    Digital Power Network Parameters Measurement
    (Společnost pro radioelektronické inženýrství, 2005-06) Hribik, Jan; Fuchs, Peter; Hruskovic, Miloslav; Michalek, Rastislav; Lojko, Branislav
    Exact measurement of the parameters of a power network is now possible by digital methods. The description of the proposed and realized instrument based on the digital sampling method is given. It can measure basic parameters of the three-phase power network such as rms values of voltages and currents, powers, energies, power factors and the network frequency. Questions concerning the accuracy of measurement, error sources, and error correction are also given. A method of calibration based on the frequency output is proposed and its calculation accuracy evaluated by MATLAB.
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    Advanced Colorimetry of Display Systems: Tetra-Chroma3 Display Unit
    (Společnost pro radioelektronické inženýrství, 2005-06) Kaiser, Jan
    High-fidelity color image reproduction is one of the key issues in visual telecommunication systems, for electronic commerce, telemedicine, digital museum and so on. All colorimetric standards of display systems are up to the present day trichromatic. But, from the shape of a horseshoe-area of all existing colors in the CIE xy chromaticity diagram it follows that with three real reproductive lights, the stated area in the CIE xy chromaticity diagram cannot be overlaid. The expansion of the color gamut of a display device is possible in a few ways. In this paper, the way of increasing the number of primaries is studied. The fourth cyan primary is added to three conventional ones to enlarge the color gamut of reproduction towards cyans and yellow-oranges. The original method of color management for this new display unit is introduced. In addition, the color gamut of the designed additive-based display is successfully compared with the color gamut of a modern subtractive-based system. A display with more than three primary colors is called a multiprimary color display. The very advantageous property of such display is the possibility to display metameric colors.
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    Cross-Wire Calibration for Freehand 3D Ultrasonography: Measurement and Numerical Issues
    (Společnost pro radioelektronické inženýrství, 2005-06) Anagnostoudis, Asterios; Jan, Jiri
    3D freehand ultrasound is an imaging technique, which is gradually finding clinical applications. A position sensor is attached to a conventional ultrasound probe, so that B-scans are acquired along with their relative locations. This allows the B-scans to be inserted into a 3D regular voxel array, which can then be visualized using arbitrary-plane slicing, and volume or surface rendering. A key requirement for correct reconstruction is the calibration: determining the position and orientation of the B-scans with respect to the position sensor's receiver. Following calibration, interpolation in the set of irregularly spaced B-scans is required to reconstruct a regular-voxel array. This text describes a freehand measurement of 2D ultrasonic data, an approach to the calibration problem and several numerical issues concerned with the calibration and reconstruction.