1994/4

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    An Optical Carry Chain Fast Adder
    (Společnost pro radioelektronické inženýrství, 1994-12) Zhijian Hu; King, G.; Al-Dabass, D.
    A significant problem in Arithmetic Unit design and particularly for systolic arrays remains the speed attainable in achieving high speed addition. The root of the problem is carry propagation and a method is presented which is relatively independent of word length. The problem is addressed by the description of a suggested radical design involving a hybrid optical and electronic approach. The method of carry chain addition through pass gates is explained and a suggested implementation utilising Fabry-Perott resonators, optical waveguides and voltage controlled couplers is described. The design is suitable for n-stage modular expansion.
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    Simulation Modeling of Radio Direction Finding Results
    (Společnost pro radioelektronické inženýrství, 1994-12) Havlik, J.; Pelikan, K.
    It is sometimes difficult to determine analytically error probabilities of direction finding results for evaluating algorithms of practical interest. Probalistic simulation models are described in this paper that can be to study error performance of new direction finding systems or to geographical modifications of existing configurations.
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    Some Problems in Numerical Time Domain Analysis of Real Switched Capacitor Networks
    (Společnost pro radioelektronické inženýrství, 1994-12) Zaplatilek, K.
    The contribution describes some problems which are connected with an application of theoretical methods. The transformation of data fields as a result of an output signal discontinuity and the correction of the time axis length will be discussed.
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    A Digitally Programmable Differential Integrator with Enlarged Time Constant
    (Společnost pro radioelektronické inženýrství, 1994-12) Nandi, R.; Sanyal, S. K.; Debroy, S. K.
    A new Operational Amplifier (OA)-RC integrator network is described. The novelties of the design are used of single grounded capacitor, ideal integration function realization with dual-input capability and design flexibility for extremely large time constant involving an enlargement factor (K) using product of resistor ratios. The aspect of the digital control of K through a programmable resistor array (PRA) controlled by a microprocessor has also been implemented. The effect of the OA-poles has been analyzed which indicates degradation of the integrator-Q at higher frequencies. An appropriate Q-compensation design scheme exhibiting 1 : |A|2 order of Q-improvement has been proposed with supporting experimental observations.
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    Diagnostic Methods for Planar Optical Waveguides
    (Společnost pro radioelektronické inženýrství, 1994-12) Ctyroky, J.; Janta, J.; Skalsky, M.; Schrofel, J.
    Basic diagnostic methods for examining planar optical waveguides, namely the mode spectroscopy for determining the propagation constants of waveguide modes and two methods for measurement of attenuation coefficient of a waveguide or loss in some waveguide components, are presented. A promising advanced method — optical coherence-domain reflectometry — is briefly mentioned.