Telfor Journal Vol.1 No.2 (2009)

Content

Editorial HyperLink
Editor-in-Chief: Prof. Dr Đorđe Paunović

Performance Analysis of a Cooperative Diversity Scheme in Rician Fading Channel

N. Milošević, B. Dimitrijević, P. Petrović, and Z. Nikolić
Topic:
Communication Theory
Abstract
In this paper we consider performance of a cooperative diversity scheme in Rician fading channel. The analytical results obtained in this paper will be comapred to the simulation results published previously, and it will be shown that the results are in great accordance. Besides that, the influence of the number of relay nodes on the performance of the system will be analysed.
Keywords
fading channel, network cooperative diversity, outage probability, wireless networks.
Full Text
HyperLink Performance Analysis of a Cooperative Diversity Scheme in Rician Fading Channel
Page(s)
38-40

Influence of Imperfect Cophasing on Performance of MRC Receiver of QPSK Signals Transmitted over Weibull Fading Channel

G. T. Đorđević, B. Z. Nikolić, A. M. Cvetković, and M. S. Marković
Topic:
Communication Theory
Abstract
This paper presents an analysis of maximum ratio combining (MRC) receiver of quaternary phase-shift keying (QPSK) signals transmitted over a Weibull fading channel. We determine the influence of imperfect cophasing and branches unbalance on bit error rate dependence on average signal-to-noise ratio. The performance dependence on diversity order and fading severity is also observed.
Keywords
Cophasing, Diversity systems, Error probability, Fading.
Full Text
HyperLink Influence of Imperfect Cophasing on Performance of MRC Receiver of QPSK Signals Transmitted over Weibull Fading Channel
Page(s)
41-44

Two-Channel IIR Filter Banks Utilizing the Frequency-Response Masking Technique

L. D. Milić and J. D. Ćertić
Topic:
Signal Processing
Abstract
In this paper, a new approach for a twochannel IIR filter bank based on the frequency-response masking technique is presented. A model filter pair is a double complementary IIR filter pair implemented as a parallel connection of two all-pass filters. Masking filters are linear-phase FIR filters. The resulting overall filter pair is nearly power complementary, and simultaneously achieves high sub-channel selectivity. The approximately linear phase of channel filters is achieved with an IIR model filter pair of an approximately linear phase. Compared to the traditional solution based on FIR filters only, the proposed filter bank exhibits a smaller overall delay and requires a smaller number of multipliers for implementation.
Keywords
complementary filter pairs, digital filters, filter banks, frequency-response masking.
Full Text
HyperLink Two-Channel IIR Filter Banks Utilizing the Frequency-Response Masking Technique
Page(s)
45-48

Generalized Design Method for Voltage-Controlled Current-Mode Multifunction Filters

N. Herencsár, J. Koton, K. Vrba, I. Lattenberg, and J. Mišurec
Topic:
Signal Processing
Abstract
In the article, the Generalized Current Follower Transconductance Amplifier (GCFTA) element for generalized frequency filter design and a novel active element, the Programmable Current Amplifier (PCA) for the realization of the current-mode analog blocks, are presented. The paper also presents a method of general frequency filter design, whereas the basic circuit is a general autonomous circuit using GCFTA, PCA elements and general admittances. The properties of the proposed filter have been verified using PSPICE simulations.
Keywords
Active Filter, CCII+/–, Current-Mode Circuit, Generalized Current Follower Transconductance Amplifier (GCFTA), Multifunctional Filter, Programmable Current Amplifier (PCA).
Full Text
HyperLink Generalized Design Method for Voltage-Controlled Current-Mode Multifunction Filters
Page(s)
49-52

Analysis of Electromagnetic Scatterers Using Hybrid Higher Order FEM-MoM Technique

A. Ž. Ilić, S. V. Savić, M. M. Ilić, and B. M. Notaroš
Topic:
Applied Electromagnetics
Abstract
A higher order large-domain hybrid finite element – method of moments (FEM-MoM) technique is presented. The discretization and solving FEM and MoM parts of the problem and the coupling of the two methods are described. A benchmark example of analysis of a scatterer with pronounced curvature at resonant frequency is given, demonstrating accuracy and robustness of the presented hybrid technique.
Keywords
Electromagnetic analysis, finite element methods, hybrid techniques, method of moments.
Full Text
HyperLink Analysis of Electromagnetic Scatterers Using Hybrid Higher Order FEM-MoM Technique
Page(s)
53-56

Characterization and Modeling of Microwave Absorbers in the RF and Antenna Projects

V. P. Levcheva, I. I. Arestova, B. R. Nikolov, and P. I. Dankov
Topic:
Applied Electromagnetics
Abstract
Some practical problems concerning the characterization and modeling of microwave absorbers are discussed in this paper. First, a number of measurement methods are considered for determination of the relative and absolute absorbing ability of the most popular absorbing materials – foams, rubber sheets, coatings and thin films. Next, several more complicated methods for characterization of the complex dielectric parameters of the absorbers are presented and discussed. Finally, examples for modeling of microwave absorbers by 3D simulators are given.
Keywords
absorbing media, permeability measurement, permittivity measurement.
Full Text
HyperLink Characterization and Modeling of Microwave Absorbers in the RF and Antenna Projects
Page(s)
57-60

Analysis of Switching Noise on Power Planes

M. Ž. Stojilović and A. R. Djordjević
Topic:
Applied Electromagnetics
Abstract
Power delivery networks (PDNs) in modern printed circuit boards (PCBs) are usually realized using power planes. Since the planes have very low inductance, it is usually believed that such PDNs have the smallest amount of switching noise. However, in reality, the power planes can resonate. The noise at resonant frequencies can be significant and it deteriorates the PDN performance. One of the classical methods for decreasing the noise is bypassing. This paper investigates the behavior of a typical PDN and the effect that real SMD bypass capacitors produce when attached to it.
Keywords
Power-delivery networks, switching noise.
Full Text
HyperLink Analysis of Switching Noise on Power Planes
Page(s)
61-64

Intelligent Industrial Transmitters of Pressure and Other Process Parameters

M. P. Frantlović, V. J. Jovanov, and B. L. Miljković
Topic:
Applied Electronics
Abstract
An overview is given of industrial measurement instruments (transmitters) of pressure and other process parameters. It is followed by a description of the technology used in the current generation of intelligent transmitters featuring two-way digital communication. A recently developed product of IHTM–CMTM, the intelligent pressure transmitter is presented, including a description of the software temperature compensation method for the used pressure sensor. Features and application possibilities of the developed hardware and software platform are discussed, as well as its suitability for the realization of wireless sensors.
Keywords
Measurement, sensor, transmitter.
Full Text
HyperLink Intelligent Industrial Transmitters of Pressure and Other Process Parameters
Page(s)
65-68

Design Methods for Embedded Security

M. Knežević, V. Rožić, and I. Verbauwhede
Topic:
Applied Electronics
Abstract
Embedded devices need both an efficient and a secure implementation of cryptographic algorithms. In this overview paper we show a typical top-down approach for secure and efficient implementation of embedded systems. We outline the security pyramid by illustrating the five primary abstraction levels in an embedded system. Focusing only on two levels - architecture and circuit level - we show how the design can be implemented to be both efficient and secure.
Keywords
Security, embedded systems, design methods, design pyramid, public key cryptosystems (PKC).
Full Text
HyperLink Design Methods for Embedded Security
Page(s)
69-72

Modelling and Simulation of RF Multilayer Inductors in LTCC Technology

A. Čelić
Topic:
Applied Electromagnetics (Student Paper)
Abstract
This paper is aimed at presenting the models and characteristics of two types of inductors designed in LTCC (Low Temperature Cofired Ceramic) technology. We present the physical model of a 3D planar solenoid-type inductor and of a serial planar solenoid-type inductor for the RF (radio frequency) range. To verify the results obtained by using these models, we have compared them with the results obtained by employing the Ansoft HFSS electromagnetic simulator. Very good agreement has been recorded for the effective inductance value, whereas the effective Q factor value has shown a somewhat larger deviation than the inductance.
Keywords
Q factor, Physical model of inductor, Inductance, Planar solenoid inductor.
Full Text
HyperLink Modelling and Simulation of RF Multilayer Inductors in LTCC Technology
Page(s)
73-76