Volume 49, Issue 1-2, 2014

Issue 1-2, 2014


Vol. 49. No 1-2/2014
Monthly scientific and technical journal
Published by:
The Union of Electronics, Electrical Engineering and Telecommunications /CEEC/, BULGARIA




Mario Ivanov
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Behavioral modeling and simulation of digital phase-locked loops using VHDL-AMS
Marieta G. Kovacheva

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This paper presents a simulation VHDL-AMS – based model of digital phase-locked loop – PLL (DPLL) for mixed-signal applications. The described model is of behavioral type, which ensures in a large extend its versatility. ...  read more

PSpice model of a brushless machine operating in a generator mode by converting the inverter in a boost converter
Ivan P. Maradzhiev, Emil I. Dinkov

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Brushless machines are increasingly used in various fields of engineering, due to their simplicity, reliability and easy manner for control. The present paper is focused on the machine operation in a generator mode. Modeling ...  read more

Analysis of a current source supplied inverter
Peter T. Goranov

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The article describes the performance of parallel current fed inverter, supplied with ideal current source. The analytical expressions are derived, basic characteristics and parameters are shown with resistive and resonant ...  read more

A ZigBee based sensor network for road traffic monitoring
Emil E. Vladkov

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ZigBee is a popular wireless networking protocol for building self-configuring sensor networks. It proves to be both reliable and cost-effective, which makes it a preferred choice for the design of a traffic counting and monitoring ...  read more

Speech quality dependence investigation from transmission channel characteristics and voice encoding methods
Snejana G. Pleshkova, Kalina Hr. Peeva

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This article examines the dependence of speech quality from transmission channel characteristics and speech encoding methods. As speech quality estimation is proposed to use the objective methods for quality control and evaluation ...  read more

Model of information security system based on distributed data transmission
Elitsa D. Gospodinova, Tashko A. Nikolov

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This paper presents a model of security system for protection of information, transmitted over wireless networks. The model is design for implementation in terminals, having more than one independent one from another radio ...  read more

Dynamic queue management of partial shared buffer with mixed priority for QoS guarantee in LTE uplink
Georgi Balabanov, Seferin Mirtchev

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The main objective of this article is to propose and evaluate solutions for QoS guarantee of voice and multimedia traffic at the radio uplink interface of LTE networks. A novel queue named a Dynamic queue management of Partial ...  read more

Improvement of the information services by using means of the IT infrastructure library
Mario Ivanov

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In the present paper, the focus is on the process of determining effective key indicators in ITIL (Information Technology Infrastructure Library), and is provided an overview of the most popular key performance indicators. ...  read more