Telfor Journal Vol.4 No.2 (2012)

Content

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

BER Analysis of STBC Codes for MIMO Rayleigh Flat Fading Channels

L. A. Perişoară
Topic:
Communication Theory
Abstract
The paper presents the analysis of Space-Time Block Codes (STBC) used in Multiple-Input Multiple-Output (MIMO) systems to assure transmit diversity. The receive diversity is resolved with a Maximum Ratio Combining technique. For a fixed number of transmit antennas, the performances of different STBC codes are analyzed in terms of Bit Error Rate (BER) and diversity gain for a quasi-static Rayleigh flat fading channel. Finally, it is shown that by increasing the number of transmit/receive antennas, the system performances increase.
Keywords
Bit error rate, maximum ratio combiner, receive diversity, space-time block codes, transmit diversity.
Full Text
HyperLink BER Analysis of STBC Codes for MIMO Rayleigh Flat Fading Channels
Page(s)
78-82

Implementation of Middleware Switch ASIC Processor

V. Petrovic, M. Ilic, G. Schoof, and S. Montenegro
Topic:
Communication Theory
Abstract
The new spacecraft area network (SCAN) system for internal satellite communication provides data transfer between different satellite components. The satellite components have their own communication protocols, which are translated by middleware (MW) switch processor into a universal middleware protocol, understandable for the satellite operating system. The MW switch processor is the main part of a new proposed approach. Instead of current board computer based systems, the new data transfer approach based on network provides a more reliable solution. The processor is fabricated in the 250 nm IHP technology. This paper introduces a description of MW switch architecture, a comparison between possible architecture approaches and the characteristics of the implemented MW Switch processor.
Keywords
Architecture, ASIC, communication switching, middleware, reliability, satellite communication.
Full Text
HyperLink Implementation of Middleware Switch ASIC Processor
Page(s)
83-88

Integration with Energy Harvesting Technology

V. Marsic, M. Zhu, and S. Williams
Topic:
Communication Theory
Abstract
This paper reports on the design and implementation of a wireless sensor communication system with a low power consumption that allows it to be integrated with the energy harvesting technology. The system design and implementation focus on reducing the power consumption at three levels: hardware, software and data transmission. The reduction in power consumption, at hardware level in particular, is mainly achieved through the introduction of an energy-aware interface (EAI) that ensures a smart inter-correlated management of the energy flow. The resulted system satisfies the requirements of a wireless sensor structure that possesses the energy autonomous capability.
Keywords
Energy harvesting, low power consumption, wireless sensor communication system.
Full Text
HyperLink Integration with Energy Harvesting Technology
Page(s)
89-94

Evaluation of a Document Oriented Resource Directory Performance

S. Jokić, S. Krčo, I. Dejanović, J. Vučković, N. Gligorić, and D. Drajić
Topic:
Communication Theory
Abstract
In this paper, two implementations of a Resource Directory based on document oriented databases are described. Resource Directory is a directory storing descriptions of resources available in an Internet of Things system. Their performances are compared with performance of a Resource Directory with the same functionality, but implemented using a relational, SQL database. The evaluation results show that the document based Resource Directories provide more flexible management of the resources and a shorter response time.
Keywords
Document oriented databases, future Internet, IoT, native XML databases, relational databases, resources.
Full Text
HyperLink Evaluation of a Document Oriented Resource Directory Performance
Page(s)
95-100

Wavelet Denoising within the Lifting Scheme Framework

A. M. Gavrovska, M. P. Paskaš, and I. S. Reljin
Topic:
Signal Processing
Abstract
In this paper, we consider an example of the lifting scheme and present the results of the simple lifting scheme implementation using lazy transform. The paper is tutorial-oriented. The results are obtained by testing several common test signals for the signal denoising problem and using different threshold values. The lifting scheme represents an effective and flexible tool that can be used for introducing signal dependence into the problem by improving the wavelet properties.
Keywords
Dual and primal lifting step, lazy transform, lifting scheme, wavelets.
Full Text
HyperLink Wavelet Denoising within the Lifting Scheme Framework
Page(s)
101-106

Realization of Multistage FIR Filters using Pipelining-Interleaving

M. Ciric and V. Radonjic
Topic:
Signal Processing
Abstract
Multistage digital filters can be one of the solutions for the realization of filters with a narrow transition zone. If requirements for the width of transition zone are too strict, then they are the only alternative, and the decimation/interpolation must be performed in several steps. Combining decimation/interpolation operations related to the implementation of multi-channel filters in the PI (pipelining/interleaving) technique can give an efficient structure of multichannel multistage filter. Using the advantages offered by newer generations of FPGA chips in terms of digital design structure, it is possible to realize such filters with considerable savings of hardware resources and reduce the effect of finite length codeword. This paper proposes such an efficient implementation and presents the results of such a realization with FPGA components.
Keywords
Critical loop limitation, digital filtering, effect of finite length codeword, multistage filter, pipelining/interleaving technique.
Full Text
HyperLink Realization of Multistage FIR Filters using Pipelining-Interleaving
Page(s)
107-110

Subjective Video Quality Assessment in H.264/AVC Video Coding Standard

Z. Miličević and Z. Bojković
Topic:
Multimedia
Abstract
This paper seeks to provide an approach for subjective video quality assessment in the H.264/AVC standard. For this purpose a special software program for the subjective assessment of quality of all the tested video sequences is developed. It was developed in accordance with recommendation ITU-T P.910, since it is suitable for the testing of multimedia applications. The obtained results show that in the proposed selective intra prediction and optimized inter prediction algorithm there is a small difference in picture quality (signal-to-noise ratio) between decoded original and modified video sequences.
Keywords
H.264/AVC standard, peak signal-to-noise ratio, subjective video coding quality assessment.
Full Text
HyperLink Subjective Video Quality Assessment in H.264/AVC Video Coding Standard
Page(s)
111-115

Improving CBIR Systems Using Automated Ranking

G. J. Zajić, N. S. Kojić, and B. D. Reljin
Topic:
Multimedia
Abstract
The most common way of searching images on the Internet and in private collections is based on a similarity measuring of a series of text words that are assigned to each image with users query series. This method imposes strong constraints (the number of words to describe the image, the time necessary to thoroughly describe the subjective experience of images, the level of details in the picture, language barrier, etc.), and is therefore very inefficient. Modern researches in this area are focused on the contentbased searching images (CBIR). In this way, all described disadvantages are overcome and the quality of searching results is improved. This paper presents a solution for CBIR systems where the search procedure is enhanced using sophisticated extraction and ranking of extracted images. The searching procedure is based on extraction and preprocessing of a large number of low level image features. Thus, when the user defines a query image, the proposed algorithm based on artificial intelligence, shows to the user a group of images which are most similar to a query image by content. The proposed algorithm is iterative, so the user can direct the searching procedure to an expected outcome and get a set of images that are more similar to the query one.
Keywords
CBIR, feature, image databases, neural networks, ranking, searching.
Full Text
HyperLink Improving CBIR Systems Using Automated Ranking
Page(s)
116-121

On Predictive-Based Lossless Compression of Images with Higher Bit Depths

A. Avramović and G. Banjac
Topic:
Multimedia
Abstract
Due to the rapidly increasing requirements for data transmission and storage, applications for fast and efficient compression of data have a very important role. Lossless compression must be applied when data acquisition is expensive. For example, lossless image compression must be applied in aerial, medical and space imaging. Besides the requirements for high compression ratios as much as it is possible, lossless image coding algorithms should be as fast as possible. During the late nineties of the previous century, many predictive-based algorithms for lossless compression of 8-bit images were introduced. These algorithms were usually expanded to enable processing of images with higher bit depths. All predictive based algorithms used more or less efficient predictors to remove spatial redundancy in images. This paper gives a comparative analysis of predictor efficiency with special emphasis on images with higher bit depths. A novel predictive-based, lossless image compression algorithm with a simple context-based entropy coder is presented, as well. A comparison with standardized lossless compression algorithms JPEG-LS and JPEG2000 is made on a large set of 12-bit medical images of different modalities and 12-bit and 16-bit natural images. It is shown that the proposed solution can achieve approximately the same bitrates as standardized algorithms even though it is much simpler.
Keywords
Bit depth, compression, lossless, medical images, prediction.
Full Text
HyperLink On Predictive-Based Lossless Compression of Images with Higher Bit Depths
Page(s)
122-127

The Practical Design of In-vehicle Telematics Device with GPS and MEMS Accelerometers

M. B. Vukajlović, S. Tadić, and D. M. Dramićanin
Topic:
Applied Electronics
Abstract
The latest generation of vehicle tracking devices relies not only on Global Positioning System (GPS) but also uses low-cost Micro-Electro-Mechanical Systems (MEMS) accelerometers. This combination supports new services such as driving style characterization and Automatic Crash Notification (ACN). Our focus will be on practical considerations of such a telematics unit. The paper will consider the boundaries of allowed errors and minimal requirements for sensors and mounting requirements. Sensor range for crash detection and impact angle estimation was tested on field trials with two units containing accelerometers range of 18g and 2g. The kinematic orientation of vehicle is evaluated in a series of field trials with a resulting standard deviation of estimation of 1.67°. The second run of experiments considers the dynamic range and sampling rate of sensors during collision. A sensor range of 8g (typical for present-day telematics devices) can be used to detect crash without accurate knowledge of impact angle.
Keywords
Accelerometer, advanced vehicle tracking, automatic crash notification, GPS, telematics.
Full Text
HyperLink The Practical Design of In-vehicle Telematics Device with GPS and MEMS Accelerometers
Page(s)
128-132

Simple and Low-cost Fiber-optic Sensors for Detection of UV Radiation

A. V. Joža, J. S. Bajić, D. Z. Stupar, M. P. Slankamenac, M. Jelić, and M. B. Živanov
Topic:
Applied Electronics
Abstract
In this paper two simple and low-cost fiberoptic sensors for detection of UV radiation are presented. A U-shaped sensor covered with an UV marker for UV radiation detection and a fiber-optic sensor with one end covered with powder from a mercury lamp are produced and described in details. Both sensors are made of large-core PMMA plastic optical fibers. As UV sources, a solar simulator and four different UV lamps are used. The light spectrum on the fiber output is measured by using an USB spectrometer. Dependence of output light intensity on the distance of end-type sensor with powder from a mercury lamp from UV lamp is investigated as well. On the output of the sensor covered with powder from a mercury lamp are obtained peaks of fluorescent emission at approximately 616 nm and 620 nm wavelengths.
Keywords
Fiber-optic, powder from mercury lamp, U-shaped, UV marker, UV sensor.
Full Text
HyperLink Simple and Low-cost Fiber-optic Sensors for Detection of UV Radiation
Page(s)
133-137

On-Wafer Measurements for Extraction of Effective Dielectric Constant in IC Transmission Lines on Multilayer Substrates

R. G. Arnaudov, R. B. Borisov
Topic:
Applied Electronics
Abstract
Methodology for extracting an effective dielectric constant of microstrip transmission lines on multilayer substrates, from measured or simulated S-parameters data, using on-chip test structures, has been demonstrated. The methodology consists of: 1) building on-chip interconnect structures usually implemented in calibration and de-embedding procedures in microwave on-wafer test and measurements – transmission lines, stubs and pad launchers; 2) extracting the effective dielectric constant from the characteristic impedance and propagation constant of these structures, fully described by the measured or EM-simulated S-parameters. The demonstrated methodology is applicable for evaluation of dielectric and semiconductor multilayer substrates, both with lossy and lossless characteristics over a broad frequency band. Another advantage is implementation of very short transmission line structures with physical dimensions much smaller than a quarter wavelength of the highest investigated band frequency, thus preserving a valuable chip area in the test structures and being compatible with some of the calibration TRL elements.
Keywords
Calibration and de-embedding structures, characteristic impedance, effective dielectric constant, multilayer substrates, on-wafer test and measurements, propagation constant, S-parameters.
Full Text
HyperLink On-Wafer Measurements for Extraction of Effective Dielectric Constant in IC Transmission Lines on Multilayer Substrates
Page(s)
138-143

Signal Acquisition and Processing in the Magnetic Defectoscopy of Steel Wire Ropes

I. D. Radovanović, N. M. Rajović, V. M. Rajović, and N. S. Jovičić
Topic:
Applied Electronics
Abstract
The system that resolves the problem of wire rope defects using a magnetic method of inspection is presented in this paper. Implementation of the system should provide for full monitoring of wire rope condition, according to the prescribed international standards. The purpose of this system, in addition to identifying defects in the rope, is to determine to what extent damage has been done. The measurement procedure provides for a better understanding of the defects that occur, as well as the rejection criteria of used ropes, that way increasing their security. Hardware and software design of appliance for recording defects and test results are presented in this paper.
Keywords
magnetic defectoscopy, magnetic sensor, steel wire ropes.
Full Text
HyperLink Signal Acquisition and Processing in the Magnetic Defectoscopy of Steel Wire Ropes
Page(s)
144-148

A Comparison of Different Engineering Models for Computation of Lightning Magnetic Field of Negative First Strokes

V. Javor
Topic:
Applied Electromagnetics
Abstract
A comparison of different engineering models results for a lightning magnetic field of negative first strokes is presented in this paper. A new function for representing double-peaked channel-base current is used for lightning stroke modeling. This function includes the initial and subsidiary peak in a current waveform. For experimentally measured currents, a magnetic field is calculated for the three engineering models: transmission line (TL) model, TL model with linear decay (MTLL), and TL model with exponential decay (MTLE).
Keywords
Channel-base current, electromagnetic field, lightning discharge, lightning stroke model, return stroke.
Full Text
HyperLink A Comparison of Different Engineering Models for Computation of Lightning Magnetic Field of Negative First Strokes
Page(s)
149-154

Frequency Hopping Method for Audio Watermarking

A. Anastasijević and D. Čoja
Topic:
Multimedia (Student Paper)
Abstract
This paper evaluates the degradation of audio content for a perceptible removable watermark. Two different approaches to embedding the watermark in the spectral domain were investigated. The frequencies for watermark embedding are chosen according to a pseudorandom sequence making the methods robust. Consequentially, the lower quality audio can be used for promotional purposes. For a fee, the watermark can be removed with a secret watermarking key. Objective and subjective testing was conducted in order to measure degradation level for the watermarked music samples and to examine residual distortion for different parameters of the watermarking algorithm and different music genres.
Keywords
Audio watermarking, copyright protection, frequency hopping method, pseudo-random noise.
Full Text
HyperLink Frequency Hopping Method for Audio Watermarking
Page(s)
155-160

Comments on “Reverberation Radius in Real Rooms”

P. Jafari Shalkouhi
Topic:
Multimedia (Letters to the Editor)
Abstract
The goal of this letter is to comment on the article "Reverberation Radius in Real Rooms" by Mijić and Mašović (2010). Mijić and Mašović measured critical distance and reverberation time in four different size rooms from 125 Hz to 4 kHz octave bands. They proposed a method for measurement of critical distance. This paper confirms that the measurements of critical distance made by Mijić and Mašović were not accurate at some frequencies.
Keywords
Critical distance, reverberation time, room modes.
Full Text
HyperLink Comments on “Reverberation Radius in Real Rooms”
Page(s)
161-162

Response to “Comments on Reverberation Radius in Real Rooms”

M. Mijić and D. Mašović
Topic:
Multimedia (Letters to the Editor)
Abstract
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Keywords
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Full Text
HyperLink Response to “Comments on Reverberation Radius in Real Rooms”
Page(s)
163-164