# September 1996, Volume 5, Number 3

**M. Harakal, J. Chmurny**
[full-text]

Image Generation by Octree

This paper deals with the generating of three-dimensional (3-D) images by octree and using the application of tesseral theory in image processing.

**M. Brejl**
[full-text]

Restoration of Local Degradations in Audio Signals

The paper presents an algorithm for restoration of local degradations in audio signals. The theoretical foundations and basic suggestions of this algorithm were published in [1]. A complete description of restoration process and some improvements are presented here.

**K. Vlcek, J. Popelek**
[full-text]

Analog Hardware Description Language and Its Relations to VHDL

Primary motivations for analogue hardware description language (VHDL-A) is to support the modelling of physical systems. The VHDL-A must therefore allow to model the physical conservation laws, such as the energy conservation law, which states that energy can neither be created nor destroyed, but it can only change its form.

**M. Hajny**
[full-text]

Interference Fading Prediction on the Line-of-Sight Radio Links

The fading on the LOS links is an important factor influencing the reliability of the communication. In this paper predictions models for interference fading are described. Predictions are compared with measured data of the experiment of TESTCOM & CTU PRAGUE in the frequency 13 GHz.

**O. Fiser**
[full-text]

Prediction of Rain and Water Vapour Attenuation at Frequencies 10-30 GHz

This contribution discusses the attenuation of microwaves in the atmosphere and applies the results to the conditions in the Czech Republic. The simple CCIR method predicting the rain attenuation is described and the relevant rain intensity as the only meteorological parameter required is presented on a map. Five methods of evaluation of the water vapour attenuation are discussed and compared . Included is also the computation of the zenith water vapour attenuation and its distribution based on the statistical evaluation of real four-year vertical profiles of important meteorological parameters from the Prague station.

**A. Urbas, B. Galinski**
[full-text]

Unbalanced Czarnul Resistive MOS Circuit in the Symmetrical MOSFET-C Filters

The analysis of influence of mismatches of the MOS transistor array on center frequency
ω_{0} and Q-factor of the MOSFET-C filter poles is performed. As a useful parameter characterizing mismatches of transistors, the dispersion of the threshold voltage V_{T} and transconductance K per unit area in the VLSI process is considered The optimal formula for the control gate voltages
V_{G1}, V_{G2} of MOS transistors, minimizing the absolute errors of ω_{0} , Q parameters is given.