Volume 49, Issue 11-12, 2014

Issue 11-12, 2014


Vol. 49. No 11-12/2014
Monthly scientific and technical journal
Published by:
The Union of Electronics, Electrical Engineering and Telecommunications /CEEC/, BULGARIA




Marin V. Nedelchev, Ilia G. Iliev
 ...  read more

Research of miniaturized hexagonal resonators

Abstract: This paper presents and researches the application of miniaturized hexagonal resonators in microstrip bandpass filters in the mobile communication systems. There are investigated both basic topologies of miniaturized hexagonal ...  read more

Application of high order APSK modulations in satellite digital video broadcasting

In this paper are presented the results of a study of the characteristics of the DVB-S2 channels when using 32APSK and 64APSK modulation. Expressions for determining the probability of bit error after APSK demodulator, LDPC and BCH ...  read more

DOA algorithms noise performance analysis for cognitive radio systems

In this paper the precision of variety direction of arrival (DOA) algorithms used in cognitive radio systems are investigated. The researched algorithms are MUSIC, Capon (MVDR), ROOT MUSIC, ESPRIT-LS and ESPRIT-TLS. The goal of this ...  read more

Transmission quality assurance in the design of HFC television network

The paper deals with signal degradation due to noise and nonlinear distortion in the forward channel of HFC television network. A mathematical model of the optical channel is presented that makes it possible for the following parameters ...  read more

Optimal divergence of laser beam in optical wireless communication systems

DОtОrmТnТng tСО optТmal dТvОrgОncО oП transmТttОr’s bОam Тn optТcal аТrОlОss communТcatТon systems (OWCS) can largely compensate for the negative impact of the change in the direction of propagation of optical ...  read more

Computer simulation of distortions in optical fiber for CATV systems

A general overview of most problems appearing when signals are transmitted in the fiber optic part of a CATV system is made. Some basic theoretical dependencies, as well as numerical methods suitable for computer simulation, are studied. ...  read more

Synthesis of microstrip filters based on miniaturized hexagonal resonators

The paper proposes the application of the miniaturized hexagonal resonators in the microstrip filter design and their applicability in mobile communication systems. The main coupling topologies are researched and the coupling mechanism ...  read more