2000/4

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    Identifying the Deterministic Chaos by Using the Lorenz Maps
    (Společnost pro radioelektronické inženýrství, 2000-12) Kvarda, P.
    This paper presents an investigation of the deterministic and stochastic chaos. The modified Colpitts oscillator is used as an example of deterministic chaos in electronic circuits. The graphical method of Lorenz maps is used for graphical observation of both chaotic classes.
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    Mutual Relations between Multiple-Input Linear and Multiple-Feedback
    (Společnost pro radioelektronické inženýrství, 2000-12) Pospisil, J.; Horska, J.
    State models of multiple-input linear non-autonomous dynamical systems are modified to the autonomous form using a multiple piecewise-linear (PWL) feedback. By such a way the corresponding state models of PWL autonomous dynamical system topologically conjugate to Lur'e systems [4] can be derived. As an example, the canonical state models of multiple-input linear and the corresponding multiple PWL feedback systems are proposed. Their state matrix equations and the integrator-based circuit models are shown.
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    Pixel Decimation in Block Matching Techniques
    (Společnost pro radioelektronické inženýrství, 2000-12) Radoczi, P.; Levicky, D.
    Block motion estimation using full search algorithm is computationally extensive. Previously proposed fast algorithms reduce the computation cost by limiting the number of locations searched. In this paper we present algorithms for block motion estimation that produce similar performance to that full search algorithm. The algorithms are based on the pixel decimation.
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    Fractal Image Coding with Digital Watermarks
    (Společnost pro radioelektronické inženýrství, 2000-12) Candik, M.; Levicky, D.; Klenovicova, Z.
    In this paper are presented some results of implementation of digital watermarking methods into image coding based on fractal principles. The paper focuses on two possible approaches of embedding digital watermarks into fractal code of images - embedding digital watermarks into parameters for position of similar blocks and coefficients of block similarity. Both algorithms were analyzed and verified on gray scale static images.
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    Modulation Schemes for Wireless Access
    (Společnost pro radioelektronické inženýrství, 2000-12) Javornik, T.; Kandus, G.; Vejrazka, F.
    Four modulation schemes, namely minimum shift keying (MSK), Gaussian minimum shift keying (GMSK), multiamplitude minimum shift keying (MAMSK) and π/4 differential quadrature phase shift keying (π/4-QPSK) are described and their applicability to wireless access is discussed in the paper. Low complexity receiver structures based on differential detection are analysed to estimate the performance of the modulation schemes in the additive Gaussian noise and the Rayleigh and Rice envelope fast fading channel. The bandwidth efficiency is calculated to evaluate the modulation schemes. The results show that the MAMSK scheme gives the greatest bandwidth efficiency, but its performance in the Rayleigh channel is rather poor. In contrast, the MSK scheme is less bandwidth efficient, but it is more resistant to Rayleigh fading. The performance of π/4-QPSK signal is considerably improved by appropriate prefiltering.