1996/2

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    Design of IIR Filters by Impulse Response Optimisation
    (Společnost pro radioelektronické inženýrství, 1996-06) Novotny, M.; Jan, J.
    The contribution describes a program system to design digital IIR filters by optimisation of impulse response. Besides briefly presenting the already published method, it emphasizes the necessity to regularize the problem by changing the requested impulse response into a causal one by reshuffling its values. The program enables to design the filters starting from either frequency or time domain response and also from a manually prescribed pole configuration which is particularly useful for teaching purposes.
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    The Current Distribution and Characteristic Impedance of Multiwire Hexaedric Antenna
    (Společnost pro radioelektronické inženýrství, 1996-06) Novacek, Z.
    Both the current distribution and characteristic impedance variations along a hexaedric antenna are analysed in this paper. The presented arrangement by auxiliary wires may ensure equal currents in all antenna wires. The results are required for calculations of the field in the operating volume and may be used for antenna design.
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    Broadband Utilization of Eigenvalue Techniques
    (Společnost pro radioelektronické inženýrství, 1996-06) Nebus, F.; Kus, Z.
    A large number of signal processing problems are concerned with estimating unknown parameters from sensor array measurement. This paper presents simple algorithm for estimating spatio-temporal spectrum of signals received by passive array derivated from MUSIC algorithm, based on eigenstructure of covariance matrices of received signals. Some simulation results are presented.
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    Optimizing Transmission Line Matching Circuits
    (Společnost pro radioelektronické inženýrství, 1996-06) Novak, S.
    When designing transmission line matching circuits, there exist often overlooked, additional, not much used, degree of choice in the selection of the transmission line impedance. In this work are presented results of CAD analysis for the two element transmission line matching networks, demonstrating that selecting matching circuits transmission lines with higher impedance, than usually used 50 or 75 ohms, can in most cases substantially decrease the physical dimension of the final matching circuit. Computer program, analyzing the influence of the matching line impedance on the length of the matching elements was developed and results are presented. It appears, that it is advantageous to choose matching circuits with high characteristic impedance. This results in a reduced dimension of the matching circuits.
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    Preliminary Results of Ocular Artefacts Identification in EEC Series by Neural Network
    (Společnost pro radioelektronické inženýrství, 1996-06) Kofronova, M.
    The human electroencephalogram (EEG), is record of the electrical activity of the brain and contains useful diagnostic information on a variety of neurological disorders. Normal EEG signal are usually registered from electrodes placed on the scalp, and are often very small in amplitude, of 20 µV. The EEG, like all biomedical signals, is very susceptible to a variety of large signal contamination or artefacts (signals of other than brain activity) which reduce its clinical usefulness. For example, blinking or moving eyes produces large electrical potentials around the eyes called the electrooculogram (EOG). The EOG spreads across the scalp to contaminate the EEG, when it is referred to as an ocular artefact (OA). This paper includes method of identification portion of the EEG record where ocular artefact appears and classification its type by neural network.