Telfor Journal Vol.5 No.2 (2013)

Content

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

Frequency Offset Influence on MDPSK Signal Reception in Fading Channel

S. N. Stošović, B. R. Dimitrijević, N. D. Milošević, and Z. B. Nikolić
Topic:
Communication Theory
Abstract
The symbol error probability of M-ary differential phase shift keying (MDPSK) receiver, in the presence of carrier frequency offset, is analysed in this paper. The paper proposes a novel multiple symbol differential detection (MSDD) receiver. The influence of various receiver’s parameters on the error probability is analysed. The theoretical symbol error probability is derived and compared to the Monte-Carlo simulation results, for an AWGN channel. The analysis shows a good agreement between the theoretical and simulation results. The influence of the frequency offset in the Rician fading channel, using Monte-Carlo simulation, is also considered for the same receiver’s parameters as in the AWGN channel. Simulation results show good system performances in the case of Rician fading channel, also.
Keywords
Adaptive signal processing; Differential phase shift keying; Frequency offset; Multiple-symbol differential detection, Rician fading channel.
Full Text
HyperLink Frequency Offset Influence on MDPSK Signal Reception in Fading Channel
Page(s)
88-91

Influence of Frequency Offset on Modified EGC Diversity Receiver

B. Z. Nikolić, B. R. Dimitrijević, N. D. Milošević, and G. T. Đorđević
Topic:
Communication Theory
Abstract
In this paper a performance analysis of a modified M-ary phase-shift-keying (MPSK) signal diversity receiver with a predetection equal gain combiner (EGC) will be presented. The modification is in introducing a structure that performs the estimation with remodulation (ER). The EGC combining is realized by using a constant modulus algorithm (CMA). The influence of carrier frequency offset, length of ER structure and other parameters of the receiver will be examined.
Keywords
Constant modulus algorithm, diversity, estimation with remodulation, frequency offset, phase-locked loop.
Full Text
HyperLink Influence of Frequency Offset on Modified EGC Diversity Receiver
Page(s)
92-96

Performance Analysis of Iterative Decoding Algorithms for PEG LDPC Codes in Nakagami Fading Channels

O. Al Rasheed, D. M. Radović, and P. N. Ivaniš
Topic:
Communication Theory
Abstract
In this paper we give a comparative analysis of decoding algorithms of Low Density Parity Check (LDPC) codes in a channel with the Nakagami distribution of the fading envelope. We consider the Progressive Edge-Growth (PEG) method and Improved PEG method for the parity check matrix construction, which can be used to avoid short girths, small trapping sets and a high level of error floor. A comparative analysis of several classes of LDPC codes in various propagation conditions and decoded using different decoding algorithms is also presented.
Keywords
Progressive edge-growth, extrinsic message degree, Belief propagation, Nakagami fading, trapping sets, Gradient Descent Bit-Flipping.
Full Text
HyperLink Performance Analysis of Iterative Decoding Algorithms for PEG LDPC Codes in Nakagami Fading Channels
Page(s)
97-102

Application of Neural Networks in Whispered Speech Recognition

Đ. T. Grozdić, B. Marković, J. Galić, and S. T. Jovičić
Topic:
Signal Processing
Abstract
This paper presents the preliminary results of experimental research of whispered speech recognition that was based on the application of artificial neural networks (ANN). The paper also describes a speech database of words that were spoken in a whisper and normal manner, which was created especially for this study. A part of this database was used for preliminary training and testing of the ANN. Mel Frequency Cepstral Coefficients (MFCC) in normal speech and whispered speech were used as an input to the ANN. The case of speaker dependent recognition was tested and ANNs with optimal topologies have a 97.98% accuracy in speech recognition and 96.21% in whisper recognition for a male speaker. The results for a female speaker were very similar. In the case of whisper recognition, when ANN was trained for normal speech the score of whisper recognition was 75.71% for a male speaker (82.14% for female), and vice versa, when ANN was trained for whisper, normal speech recognition was 82.14% for a male speaker (90% for female).
Keywords
Neural networks, speech recognition, whisper recognition, whispered speech database.
Full Text
HyperLink Application of Neural Networks in Whispered Speech Recognition
Page(s)
103-106

Approximately Liner Phase IIR Digital Filter Banks

J. D. Ćertić, M. D. Lutovac, and L. D. Milić
Topic:
Signal Processing
Abstract
In this paper, uniform and nonuniform digital filter banks based on approximately linear phase IIR filters and frequency response masking technique (FRM) are presented. Both filter banks are realized as a connection of an interpolated half-band approximately linear phase IIR filter as a first stage of the FRM design and an appropriate number of masking filters. The masking filters are half-band IIR filters with an approximately linear phase. The resulting IIR filter banks are compared with linear-phase FIR filter banks exhibiting similar magnitude responses. The effects of coefficient quantization are analyzed.
Keywords
approximately linear phase IIR filters, FRM, non-uniform filter bank, uniform filter bank.
Full Text
HyperLink Approximately Liner Phase IIR Digital Filter Banks
Page(s)
107-112

Non-Stationary Two-Dimensional Subband Transformer Filters

V. Čeperković and M. Prokin
Topic:
Signal Processing
Abstract
State-of-the-art two-dimensional subband transformation based compression methods typically require large memory size and memory bus bandwidth. This paper discloses a novel method for reducing both shortcomings, and even provides compression or decompression from the cache memory. This solution can be implemented either in software or hardware or their combination, as a front stage in either lossless or lossy image encoder or a back stage in either lossless or lossy image decoder.
Keywords
Image compression, subband transformation, non-stationary filters.
Full Text
HyperLink Non-Stationary Two-Dimensional Subband Transformer Filters
Page(s)
113-117

High-quality Crystal Filter – Design and Realization

D. M. Dujković, S. Dedić Nešić, L. Grubišić, A. Gavrovska, and I. Reljin
Topic:
Signal Processing
Abstract
Analog oscillators and filters are still very important devices in modern telecommunication and measurement equipment. Quartz crystal units are used for high-quality oscillators and filters, due to their extremely stable resonant frequency and Q-factor. In this paper the design and realization of a high-quality bandpass quartz crystal filter with a possible application to antenna circuitry is described.
Keywords
Crystal units, crystal filters, filter design, filter realization, communications, digital communications.
Full Text
HyperLink High-quality Crystal Filter – Design and Realization
Page(s)
118-122

Morphological and Median Adaptive Filters Based on LCBP Rank Filter

D. Prokin and M. Prokin
Topic:
Signal Processing
Abstract
The presented median and morphological (min and max) filters based on low complexity bit-pipeline (LCBP) rank filter provide reduced complexity of required processing hardware, due to similar pipeline stages and the complete absence of sorting networks in comparison with other solutions. FPGA realization of bit-pipeline median and morphological filter and adaptive bit-pipeline rank filter according to this paper provides significantly higher maximum operating frequency and much smaller used chip resources in comparison with state-of-the-art sorting methods.
Keywords
Median filters, morphological filters, adaptive filters, pipeline processing, FPGA implementation.
Full Text
HyperLink Morphological and Median Adaptive Filters Based on LCBP Rank Filter
Page(s)
123-127

Color Multifocus Image Fusion Using Empirical Mode Decomposition

S. Savić and Z. Babić
Topic:
Signal Processing
Abstract
In this paper, a recently proposed grayscale multifocus image fusion method based on the first level of Empirical Mode Decomposition (EMD) has been extended to color images. In addition, this paper deals with low contrast multifocus image fusion. The major advantages of the proposed methods are simplicity, absence of artifacts and control of contrast, while this isn’t the case with other pyramidal multifocus fusion methods. The efficiency of the proposed method is tested subjectively and with a vector gradient based objective measure, that is proposed in this paper for multifocus color image fusion. Subjective analysis performed on a multifocus image dataset has shown its superiority to the existing EMD and DWT based methods. The objective measures of grayscale and color image fusion show significantly better scores for this method than for the classic complex EMD fusion method.
Keywords
Empirical Mode Decomposition (EMD), Discrete Wavelet Transform (DWT), image fusion, multifocus, low contrast.
Full Text
HyperLink Color Multifocus Image Fusion Using Empirical Mode Decomposition
Page(s)
128-133

Laboratory Experimental System for Examination of Acoustic Emission Generated by Partial Discharges

I. M. Salom, V. V. Čelebić, J. J. Gajica, N. M. Kartalović, M. M. Mijić, V. V. Sekulić, and M. I. Radulović
Topic:
Multimedia
Abstract
One of the major causes of transformer failures is dielectric breakdown. Partial discharges cause gradual insulation degradation thus partial discharge activity monitoring provides transformer state insight. This paper gives an overview of common methods for partial discharges detection and source location in transformers, with a special reference to the acoustic method as an noninvasive and interference resistant method suitable for application. For laboratory testing a laboratory experimental system for partial discharge diagnostics using acoustic emission measurement was developed.
Keywords
Acoustic emission, partial discharges, online measurement, diagnostics, transformers.
Full Text
HyperLink Laboratory Experimental System for Examination of Acoustic Emission Generated by Partial Discharges
Page(s)
134-139

Sound Generating Mechanism of the Double Bass

F. Pantelić and J. Prezelj
Topic:
Multimedia
Abstract
This paper deals with the mechanical properties of the double bass and double bass bow. The sound of the instrument, as well as the vibrations of the bow, were recorded while playing. The sound was recorded with a microphone, while a sensor, placed on the bow’s stick, registered its vibrations. By observing these signals, from double bass and bow, the correlation between them was determined in order to explain the bow-string mechanism.
Keywords
bow, double bass, stick-slip effect, vibrations, sound.
Full Text
HyperLink Sound Generating Mechanism of the Double Bass
Page(s)
140-144

Analysis of Reverberation Time Field Measurement Results in Building Acoustics

D. Mašović and M. Öğüç
Topic:
Multimedia
Abstract
Sound level difference between two rooms depends on both sound reduction between the rooms and their acoustical properties, such as the absorption in the receiving room. In order to abstract the influence of the rooms and assess only the sound reduction between them, relevant building acoustics standards offer two ways of normalizing a measured sound level difference – according to the reverberation time and the equivalent sound absorption area in the receiving room. In both cases measurement procedure requires reverberation time measurements in the receiving room, from which the equivalent sound absorption area can be assessed using Sabine’s formula. This paper analyses more than 300 results of reverberation time field measurements and provides an insight into its typical values in buildings. The measurements are done by five teams of building acoustics engineers, mostly involved in the international EU COST Action TU0901. The results are gathered in a unique database as a part of the STSM (Short Term Scientific Mission).
Keywords
building acoustics, equivalent sound absorption area, field measurements, reverberation time.
Full Text
HyperLink Analysis of Reverberation Time Field Measurement Results in Building Acoustics
Page(s)
145-150

An Implementation of Optical Transponder and Media Converter Unit for Speeds up to 2.5 Gbps

N. Jovalekić, P. Mićović, and J. Popović-Božović
Topic:
Applied Electronics
Abstract
The paper presents the implementation of protocol agnostic optical transponder and media converter unit for speeds up to 2.5 Gbps. Detailed depiction of the implementation is given, including hardware design issues, as well as the signal integrity solutions. In addition, the design implemented in a field-programmable gate array (FPGA) chip is discussed. On the other hand, embedded software implementation is explained, as well as the interface to the network management software that executes on a PC. Finally, strategy for the verification of the unit functionalities at the end of the development stage is given, and results are presented.
Keywords
Media converter, optical transponder, optical transport systems, signal integrity.
Full Text
HyperLink An Implementation of Optical Transponder and Media Converter Unit for Speeds up to 2.5 Gbps
Page(s)
151-155

New Neural Procedure for Extraction of Parameters of Microwave FET Noise Models

N. Ivković, Z. Marinković, O. Pronić-Rančić, and V. Marković
Topic:
Applied Electronics
Abstract
A neural netwok based procedure for extraction of parameters of microwave FET noise models is proposed in this paper. The procedure is illustrated on the Pospieszalski’s noise model. A neural network is trained to predict the equivalent drain noise temperature for given values of the intrinsic circuit elements, intrinsic noise parameters, ambient temperature and frequency. In this way, the repeated extraction procedures in microwave circuit simulators are avoided. The presented approach is validated on a specific HEMT device noise modeling. The results are compared with the results obtained for the model parameters extracted by using the standard optimization based extraction procedures.
Keywords
Artifcial neural networks, equivalent noise temperatures, HEMT, MESFET, noise model.
Full Text
HyperLink New Neural Procedure for Extraction of Parameters of Microwave FET Noise Models
Page(s)
156-160

Omnidirectional Antenna with Multi-Resonance Performance for Microwave Imaging Systems

N. Ojaroudi, M. Ojaroudi, F. Geran, and S. Amiri
Topic:
Applied Electromagnetics
Abstract
In this paper, a novel ultra-wideband printed monopole antenna (PMA) for microwave imaging systems is presented. The proposed antenna provides a wide usable fractional bandwidth of more than 160% (2.12-17.87 GHz). The antenna has an ordinary square radiating patch, therefore displays a good omni-directional radiation pattern even at higher frequencies and also its radiation efficiency is greater than 82% across the entire radiating band. The designed antenna has a small size of 12×18 mm2.
Keywords
Microstrip-fed antenna, microwave imaging systems, multi-resonance performance.
Full Text
HyperLink Omnidirectional Antenna with Multi-Resonance Performance for Microwave Imaging Systems
Page(s)
161-164

Design and Efficiency Analysis of one Class of Uniform Linear Phase FIR Filter Banks

R. D. Pantić
Topic:
Signal Processing (Student Paper)
Abstract
One class of uniform linear phase filter banks with different numbers of band-pass channels will be considered in this study, concentrating on 5, 9 and 17-band filter banks and their mutual comparison concerning delay and implementation complexity. Designed banks are based on the FIR filters and frequency response masking technique and are also compared to the banks with direct realization considering complementarity and delay.
Keywords
FIR filters, interpolation, uniform filter banks, FRM.
Full Text
HyperLink Design and Efficiency Analysis of one Class of Uniform Linear Phase FIR Filter Banks
Page(s)
165-170