2003/3

Browse

Recent Submissions

Now showing 1 - 5 of 12
  • Thumbnail Image
    Item
    Exploitation of Higher Order Moments Increase the Tracking Aircraft by the Extended Alpha-Beta Filter
    (Společnost pro radioelektronické inženýrství, 2003-09) Dostal, Zdenek; Mokris, Igor
    The paper analyzes the possibility of exploitation of higher order moments for increasing the precision of tracking of a flying aircraft by the α-β filter. For tracking of a flying aircraft by the α-β filter the 3rd and 4th order moments in 3D space are used.
  • Thumbnail Image
    Item
    Using the Variable-Length Arithmetic for an Accurate Poles-Zeros Analysis
    (Společnost pro radioelektronické inženýrství, 2003-09) Dobes, Josef; Michal, Jan
    In the paper, a reduction algorithm for transforming the general eigenvalue problem to the standard one is presented for both classical full-matrix methods and a sparse-matrix technique appropriate for large-scale circuits. An optimal pivoting strategy for the two methods is proposed to increase the precision of the computations. The accuracy of the algorithms is furthermore increased using longer numerical data. First, a ORQJ.GRXEOH precision sparse algorithm is compared with the GRXEOH precision sparse and full-matrix ones. Finally, the application of a suitable multiple-precision arithmetic library is evaluated.
  • Thumbnail Image
    Item
    W-CDMA Uplink Capacity and Interference Statistics of a LongGroove-Shaped Road Microcells Using A Hybrid Propagation Model
    (Společnost pro radioelektronické inženýrství, 2003-09) Taha-Ahmed, Bazil; Calvo-Ramon, Miguel; de Haro-Ariet, Leandro
    The uplink capacity and the interference statistics of the sectors of a long groove-shaped road W-CDMA microcell are studied. A model of 9 microcells in a groove-shaped road is used to analyze the uplink. A hybrid model for the propagation is used in the analysis. The capacity and the interference statistics of the cell are studied for different sector ranges, different specific attenuation factors, different antenna side lobe levels and different bend losses.
  • Thumbnail Image
    Item
    Hybrid Scheme with Triangulations for Transform Coding
    (Společnost pro radioelektronické inženýrství, 2003-09) Partyk, Martin; Polec, Jaroslav; Kolingerova, Ivana
    Our approach to image region approximation offers a complete scheme consisting of several steps. We separate the encoding of region boundaries from the texture description. The original image is first segmented using an unsupervised segmentation method for color-texture regions. Following polygonal approximation of created regions causes the degradation of region boundaries. The triangulation is then applied to polygons and either all short edges, or all small triangles are filtered out from the triangular mesh. This results in new smaller regions. The encoding and decoding of polygons and triangles is very efficient, because we need to store only the vertices. For texture approximation we use 2D shape independent orthogonal transforms (e.g. DCT II). The texture is encoded with a code similar to JPEG arithmetic code. The encoding scheme proposed in this paper is much faster than latest approaches with polygonal approximation. We present the two triangulation algorithms - constrained greedy (CGT) and constrained Delaunay triangulation (CDT). Both CGT and CDT provide similar results.
  • Thumbnail Image
    Item
    Noise Figure Measurement of Highly Mismatched DUT
    (Společnost pro radioelektronické inženýrství, 2003-09) Sokol, Vratislav; Hoffmann, Karel; Vajtr, Jiri
    A device mismatch seriously degrades the accuracy of its noise figure characterization. A new second stage correction technique for highly mismatched device under test is proposed and compared to the standard technique. The presented method is based on additional vector measurement. It takes into account measuring receiver noise figure dependence on the DUT output mismatch besides an available gain correction. Significant accuracy improvement of measured data and decreased error variation is demonstrated. The suggested method is in principle able to eliminate all systematic errors in noise figure measurement.