September 1998, Volume 7, Number 3

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C. Florens, Z. Raida [full-text]
Adaptive Beamforming Using Genetic Algorithms

The presented submission describes how genetic algorithms can be applied to the control of adaptive antennas. The proposed optimization method is easily implementable on one hand, but relatively slowly converging and depending on the parameters of the genetic algorithms on the other hand. The disadvantages as well as some possible improvements are discussed in this paper.

E. Goven, L. Verheyen, Z. Raida [full-text]
Genetic Optimization of Wire Antennas

The presented submission describes how genetic algorithms can be applied to the optimization and design of wire antennas. The proposed optimization method is easily programmable and well understandable on one hand, but relatively slowly converging and depending on the parameters of the genetic algorithms on the other hand. The disadvantages of the method are deeply discussed and their elimination is discussed in the paper.

J. Pospisil, J. Brzobohaty, Z. Kolka [full-text]
Simple Model of Synchronized System for the Chaotic-Masked Communication

In this paper the simplest form of the compound dynamical system is considered, i.e. the second-order subsystem homogeneously synchronized by the third-order autonomous subsystem where the synchronized block is identical to a part of the synchronizing block. Simplified design formulas are defined for the case of a stable synchronized subsystem and arbitrarily chosen dynamical behaviour of the whole system including any type of chaos. The resultant state equations and the corresponding integrator-based circuit models are shown. Their utilization in chaotic-masked signal communications is suggested.

K. Vrba, J. Cajka, V. Zeman [full-text]
N-th Order Filters Using Balanced-Output CCII+/- Conveyors

A novel second-generation current conveyor is defined. A special three-port cell containing the above element is presented. A method for nth-order multifunction circuit realization is described. Two universal networks illustrate the described procedure.

K. Danek [full-text]
Efficient Use of Mobile Radio Channels

This paper deals with GMSK and 4-Level FSK modulation schemes which are adopted in the land mobile services. The analysis of group delay interaction has been carried out by approximative mathematical reflections. Better spectral efficiency, achieved together with keeping up good energetic efficiency, can be the result of the above analysis. Many current and proposed mobile data transfer applications would provide a better service, and be more spectrally efficient, if the data rates could be increased.

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