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Radioengineering

Radioeng

Proceedings of Czech and Slovak Technical Universities

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September 2008, Volume 17, Number 3

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J. Machac, P. Protiva, M. Rytir, M. Blaha, J. Zehentner [references] [full-text] [Download Citations]
Isotropic Single Negative Metamaterials

This paper presents the application of simple, and therefore cheap, planar resonators for building 3D isotropic metamaterials. These resonators are: a broadside-coupled split ring resonator with a magnetic response providing negative permeability; an electric dipole terminated by a loop inductor together with a double H-shaped resonator with an electric response providing negative permittivity. Two kinds of 3D isotropic single negative metamaterials are reported. The first material consists of unit cells in the form of a cube bearing on its faces six equal planar resonators with tetrahedral symmetry. In the second material, the planar resonators boxed into spherical plastic shells and randomly distributed in a hosting material compose a real 3D volumetric metamaterial with an isotropic response. In both cases the metamaterial shows negative permittivity or permeability, according to the type of resonators that are used. The experiments prove the isotropic behavior of the cells and of the metamaterial specimens.

  1. ENGHETA, N., ZIOLKOWSKI, R. W. Metamaterials: Physics and Engineering Explorations. Willey-IEEE Press, 2006.
  2. ELEFTHERIADES, G. V., BALMAIN, K. G. Negative-Refraction Materials: Fundamental Principles and Applications. Willey-IEEE Press, 2006.
  3. CALOZ, C., ITOH, T. Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications. Willey - Interscience, 2005.
  4. BAENA, J. D., JELINEK, L., MARQUES, R. Towards a systematic design of isotropic bulk magnetic metamaterials using the cubic point groups of symmetry. Physical Review B, 76, 2007, 245115.
  5. BAENA, J. D., JELINEK, L., MARQUES, R., ZEHENTNER, J. Electrically small isotropic three-dimensional magnetic resonators for metamaterial design. Applied Phys. Lett., 2006, vol. 88, 134108.
  6. MACHAC, J., PROTIVA, P., ZEHENTNER, J. Isotropic epsilonnegative particles. In 2007 IEEE MTT-S Int. Microwave Symp. Dig., Honolulu, USA, TH4D-03, June 2007.
  7. VERNEY, E., SAUVIAC, B., SIMOVSKI, C. R. Isotropic metamaterial electromagnetic lens. Physics Letters A, 2004, vol. 331, p. 244-247.
  8. JELINEK, L., MACHAC, J., ZEHENTNER, J. A magnetic metamaterial composed of randomly oriented SRRs. In Proceedings PIERS 2007, Beijing (China), p. 474-477.
  9. VENDIK, O. G., GASHINOVA, M. S. Artificial double negative (DNG) media composed by two different dielectric sphere lattices embedded in a dielectric matrix. In Proc. of 34th European Microwave Conference 2004, 2004, p. 1209-1212.
  10. VENDIK, B., VENDIK, O. G., ODIT, M. A. Isotropic artificial media with simultaneously negative permittivity and permeability. Special Issue of Microwave and Optical Technology Letters, 2006, vol. 48, no. 12, p. 2553-2556.
  11. JYLHA, L., KOLMAKOV, I., MASLOVSKI, S., TRETYAKOV, S. Modeling of isotropic backward-wave materials composed of resonant spheres. J. Appl. Phys., 2006, vol. 99, 043102.
  12. KUSSOW, A-G., AKYURTLU, A. Negative index of refraction metamaterial in the optical regime with randomly distributed nanoparticles. In Proceedings of Metamaterials 2007. Rome (Italy), 2007, p. 723-726.
  13. KUESTER, E. F., MEMIC, N., SHEN, S., LOUI, J. H. A double negative (DNG) composite medium based on a cubic array of layered nonmagnetic spherical particles. In URSI 2007 – CNC/USNC North American Radio Science Meeting, Ottawa (Canada), 2007, URSI282.
  14. UEDA, T., ITOH, T. Three-dimensional negative-refractive index in metamaterials composed of spherical dielectric resonators. Digest of the 2006 National Radio Science Meeting, Abstract: ueda31178.
  15. HUDLICKA, M., MACHAC, J., NEFEDOV, I. S. Triple wire medium as an isotropic negative permittivity metamaterial. Progress in Electromagnetics Research [online], 2006, no. 65, p. 233-246. Internet: http://ceta.mit.edu/PIER. ISSN 1559-8985.
  16. KUSSOW, A-G., AKYURTLU, A., SEMICHAEVSKI, A., ANGAWISITTPAN, N. Superconductor-based optically isotropic negative refraction index metamaterial at visible frequencies. In Proceedings of Metamaterials 2007. Rome (Italy), 2007, p. 525-528.
  17. ZEDLER, M., CALOZ, C., RUSSER, P. Circuital and experimental demonstration of a 3D isotropic LH metamaterial based on the rotated TLM scheme. In 2007 IEEE-MTT-S Int. Microwave Symp. Dig. Hawaii, 2007, p. 1827-1830.
  18. GRBIC, A., ELEFTHERIADES, G. V. An isotropic threedimensional negative-refractive-index transmission-line metamaterial. Journal of Applied Physics, 2005, vol. 98, p. 043106.
  19. SMITH, D. R., VIER, D. C., KOSCHNY, T., SOUKOULIS, C. S. Electromagnetic parameter retrieval from inhomogeneous metamaterials. Phys. Rev. B, 2005, vol. 71, 036617.
  20. MARQUES, R., MEDINA, F., RAFII-EL-IDRISSI, R. Role of bianisotropy in negative permeability and left-handed metamaterials. Physical Review B, 2002, vol. 65, 144440.

Keywords: Electric dipole, isotropic metamaterial, single negative metamaterial, split ring resonator.

J. Drinovsky, J. Svacina, Z. Raida [references] [full-text] [Download Citations]
Simple Models of EMI Filters for Low Frequency Range

This paper deals with mathematical simulations of EMI filters’ performance. These filters are commonly used for the suppressing of electromagnetic interference which penetrates through the power supply networks. The performance of these filters depends on terminating impedances which are plugged to the inputs and outputs clamps of the EMI filters. This paper describes the method by which it is possible to calculate the insertion loss of the filters. The method is based on the modified nodal voltage method. The circuitry of the EMI filters is used for their description. The effect of spurious components is not taken into account. The filter itself is described by set of admittance parameters, which makes the presented method more universal. The calculated results were compared with measured data of several filters for several impedance combinations. Different test setups, like asymmetrical, symmetrical, etc. were taken into account. The simplicity and accuracy of the presented method is discussed in the conclusion. The achieved accuracy is on high level. The described method is universal, but for filters with more than one current compensated inductor, the mentioned method is complicated. The size of the final equation for calculating the insertion loss rapidly increases with the number of current compensated inductors.

  1. Schaffner Holding AG, Switzerland. [online], 25-5-2008, Available at: http://www.schaffner.com/.
  2. Schurter AG, Switzerland. [online], 25-5-2008, Available at: http://www.schurter.com/.
  3. CSN CISPR 17: Methods of Measurement of the Suppression Characteristics of Passive Radio Interference Filters and Suppression Components. Czech Technical Standard. Czech Normalization Institute. Prague, November 2000. 27 pages. (in Czech).
  4. Schaffner Holding AG, Switzerland. CISPR 17 Measurements (application note). 12 pages. [online] 20-5-2008, Available at: http://www.schaffner.com.cn/sc/UploadFile/200691958328797.pdf.
  5. MIL-STD-220B: Test Method Standard - Method of Insertion Loss Measurement. Military Standard, Department of Defence, USA. June 2004. 28 pages. [online] 24-5-2008, Available at: http://www.dscc.dla.mil/Downloads/MilSpec/Docs/MILSTD- 220/std220.pdf.
  6. BIOLEK, D. Solving of Electrical Circuits. Prague: BEN, 2004. 520 pages. ISBN 80-7300-125-X. (in Czech).
  7. CAJKA, J., KVASIL, J. The Theory of Linear Circuits. Prague: SNTL, 1979. 360 pages. ISBN 04-510-79. (in Czech).
  8. DRINOVSKY, J. SVACINA, J. Estimation of EMI filter performance for the "worst-case" system. Radioengineering (Part I: Special Issue: Electromagnetic Compatibility), 2006, vol. 15, no. 4, p. 16-21, ISSN 1210-2512.
  9. Schurter AG, Switzerland. 5110 EMI filter (data sheet). 4 pages. [online] 23-6-2008, Available at: http://www.schurter.cz/pdf/english/typ 5110.pdf.
  10. Elfis spol. s r. o. EMI filters 3 A - 16 A (data sheet). 2 pages. [online] 26-6-2008, Available at: http://www.elfis.cz/pdf/filtr3-16.pdf.
  11. Schaffner Holding AG, Switzerland. 1-phase filters FN 2070 (data sheet). 4 pages. [online] 26-6-2008, [available at] http://www.schaffner.com/components/en/ pdf/Datasheet%20FN 2070%20e%2055.pdf.

Keywords: Electromagnetic compatibility EMC, EMI mains filter, insertion loss, impedance termination, filter model, modified nodal voltage method, current compensated inductors.

J. Drinovsky, J. Svacina, Z. Raida [references] [full-text] [Download Citations]
Potential Worst-case System for Testing EMI Filters Tested on Simple Filter Models

This paper deals with the approximate worst-case test method for testing the insertion loss of the EMI filters. The systems with 0.1 Ω and 100 Ω impedances are usually used for this testing. These systems are required by the international CISPR 17 standard. The main disadvantage of this system is the use of two impedance transformers. Especially the impedance transformer with 0.1 Ω output impedance is not easy to be produced. These transformers have usually narrow bandwidth. This paper discusses the alternative system with 1 Ω and 100 Ω impedances. The performance of these systems was tested on several filters’ models and the obtained data are depicted, too. The performance comparison of several filters in several systems is also included. The performance of alternate worst-case system is discussed in the conclusion.

  1. HABIGER, E. Elektromagnetische Vertraglichkeit. Heidelberg: Huthig Buch Verlag, 1992. 200 pages. ISBN 3-7785-2092-X. (in German).
  2. SCHLICKE, H., M. Assuredly effective filters. IEEE Transactions on Electromagnetic Compatibility. 1976, vol. EMC-18, no. 3, p 106-110. ISSN 0018-9375.
  3. Methods of Measurement of the Suppression Characteristics of Passive Radio Interference Filters and Suppression Components. Czech Technical Standard. Czech Normalization Institute. Prague, November 2000. 27 pages. (in Czech).
  4. MIL-STD-220B: Test Method Standard - Method of Insertion Loss Measurement. Military Standard, Department of Defense, USA. June 2004. 28 pages. [online] 24-5-2008, Available at: http://www.dscc.dla.mil/Downloads/MilSpec/Docs/MILSTD- 220/std220.pdf.
  5. DRINOVSKY, J., SVACINA, J., URBANEC, T., SIPOVA, P. Impedance Transformers. In Proceedings of the 15th International Czech-Slovak Scientific Conference Radioelektronika 2005. RADIOELEKTRONIKA 2005. Brno: Institute of Radio Electronics, FEEC, BUT, 2005, p. 362 - 365, ISBN 80-214-2904-6.
  6. DRINOVSKY, J. SVACINA, J. Estimation of EMI filter performance for the "worst-case" system. Radioengineering (Part I: Special Issue: Electromagnetic Compatibility), 2006, vol. 15, no. 4, p. 16-21, ISSN 1210-2512.
  7. DRINOVSKY, J. SVACINA, J., RAIDA, Z. Simple models of EMI filters for low frequency range. Radioengineering, 2008, vol. 17, no. 3, p. 8-14, ISSN 1210-2512.
  8. Schaffner Holding AG, Switzerland. CISPR 17 Measurements (application note). 12 pages. [online] 20-5-2008, Available at: http://www.schaffner.com.cn/sc/UploadFile/ 200691958328797.pdf.

Keywords: Electromagnetic compatibility EMC, EMI mains filter, insertion loss, impedance termination, filter model, modified nodal voltage method, current compensated inductors

J. Petrzela, J. Slezak [references] [full-text] [Download Citations]
Conservative Chaos Generators with CCII+ Based on Mathematical Model of Nonlinear Oscillator

In this detailed paper, several novel oscillator\'s configurations which consist only of five positive second generation current conveyors (CCII+) are presented and experimentally verified. Each network is able to generate the conservative chaotic attractors with the certain degree of the structural stability. It represents a class of the autonomous deterministic dynamical systems with two-segment piecewise linear (PWL) vector fields suitable also for the theoretical analysis. Route to chaos can be traced and observed by a simple change of the external dc voltage. Advantages and other possible improvements are briefly discussed in the text.

  1. SPROTT, J. C. Chaos and Time Series Analysis. Oxford University Press, 2003.
  2. GOTTLIEB, H. P. W., SPROTT, J. C., Simplest driven conservative chaotic oscillator. Physics Letters A, 2001, vol. 291, p. 385 – 388.
  3. PETRZELA, J. Wideband signal generator based on chaos. In Proceedings of the 12th Electrotechnical and Computer Conference ERK 2004. Portoroz (Slovenia), 2004, p. 61 – 64.
  4. SPROTT, J. C., LINZ, S. J. Algebraically simple chaotic flows. International Journal of Chaos Theory and Applications, 2000, vol. 5, no. 2, p. 1 - 20.
  5. PETRZELA, J., HANUS, S. On the optimization of the specific class of chaotic oscillators. In Proceedings of the 13th Electrotechnical and Computer Conference ERK 2005. Portoroz (Slovenia), 2005, p. 111 to 114.
  6. LIU, S. I., WU, D. S., TSAO, H. W., WU, J., TSAY, J. H. Nonlinear circuit applications with current conveyors. In IEE Proceedings-G, 1993, vol. 140, no. 1, p. 1 – 6.
  7. LU, J., CHEN, G. Generating multi-scroll chaotic attractors: theories, methods and applications. International Journal of Bifurcation and Chaos, 2006, vol. 16, no. 4, p. 775 – 858.

Keywords: Analog oscillator, attractor, conservative dynamics, chaos, state space.

J. Zela, K. Hoffmann, P. Hudec [references] [full-text] [Download Citations]
Errors in Measurement of Microwave Interferograms Using Antenna Matrix

New antenna matrices for both scalar and vector measurement of microwave interferograms for the frequency 2.45 GHz were developed and used for an analysis of sources of measurement errors. Influence of mutual coupling between individual antennas in an antenna matrix on a measurement of microwave interferograms, particularly on a measurement of interferogram minimum values, was studied. Simulations and measurements of interferograms, proposal of a new calibration procedure and correction method are presented. Influence of differences in radiation patterns of individual antennas of an antenna matrix on a measurement of microwave interferograms was studied as well.

  1. ROCHBLATT, D. J., SEIDEL, B. L. Microwave antenna holography. IEEE Transactions on Microwave Theory and Technique, 1992, vol. 40, no. 6, p. 1294-1300.
  2. PIERACCINI, M., LUZI, G., MECATTI, D., NOFERINI, L., ATZENI, C. A microwave radar technique for dynamic testing of large structures. IEEE Transactions on Microwave Theory and Technique, 2003, vol. 51, no. 5, p. 1603-1609.
  3. SEMENOV, S. Y., et al. Spatial resolution of microwave tomography for detection of myocardial ischemia and infarctionexperimental study on two-dimensional models. IEEE Transact.s on Microwave Theory and Technique, 2000, vol. 48, no. 4, p. 538-544.
  4. BENLARBI-DELA, A., COUSIN, J. C. 3D indoor micro location using a stereoscopic microwave phase sensitive device. In IEEE MTT-S Int. Microwave Symposium Digest, 2003, p. 623-626.
  5. MOHON, R. J., MURPHY, J. A., LANIGAN, W. Digital holography at millimetre wavelengths. Optical Communications, 2006, vol. 260, no. 2, p. 469-473.
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Keywords: Interferometry, microwave measurements, calibration

R. Galuscak, P. Hazdra [references] [full-text] [Download Citations]
Dual-band Loop Feed with Enhanced Performance

This paper is aimed on specific problems of electrically small and deep dish parabolic antennas. Since these antennas may suffer with low efficiency authors describe design and optimization of simple dual-band loop prime-focus feed achieving good efficiency for these antennas.

  1. CUPIDO, L. 70 cm deep dish feed. DUBUS - Magazine for Amateur Radio on VHF/UHF and Microwaves. 2002, no. 2, ISSN 1438-3705.
  2. KOELLNER, R. Parabolic Dish Ring Feed. [online]. Available at http://www.qsl.net/dl4mea/ringfeed.htm
  3. WADE, P. Multiple Reflector Dish Antennas. [online]. Available at http://www.w1ghz.org/antbook/conf/Multiple_reflector_antennas.pdf
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  7. Computer Simulation Technology, www.cst.de
  8. FEKO EM systems-Software & SS.A. (Pty) Ltd, www.feko.info
  9. ERA Pardubice, www.era.cz
  10. www.iaru.org

Keywords: Loop feed, prime-focus feed, dish antenna

J. Pidanic, D. Cermak, V. Schejbal [references] [full-text] [Download Citations]
Gain Estimation of Doubly Curved Reflector Antenna

A simple formula of approximate gain estimation is verified for the doubly curved reflector antenna. Numerical simulations using physical optics and experimental results of the shaped-beam doubly curved reflector antenna are compared with the simple approximation of gain. That approximation could be very valuable for system engineers to accurately estimate antenna gain and coverage pattern and perform EMC calculations (estimations of interferences and susceptibilities) even for the operation and out of operation frequency bands of shapedbeam antenna.

  1. STUTZMAN, W. L. Estimating directivity and gain of antennas. IEEE Antennas and Propagation Magazine, 1998, vol. 40, no. 4, p. 7 to 11.
  2. SCHEJBAL, V. Directivity of planar antennas. IEEE Antennas and Propagation Magazine, 1999, vol. 41, no. 2, p. 60 - 62.
  3. SILVER, S. Microwave Antenna Theory and Design. New York: McGraw-Hill, 1949.
  4. KUHN, R. Mikrowellen Antennen. Berlin: VEB Verlag Technik, 1964 (in German).
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  8. SCHEJBAL, V., KUPCAK, D. A survey of programs for calculating microwave antennas with the aid of a computer. Slaboproudy obzor, 1976, vol. 37, no. 3, p. 117 – 122 (in Czech).
  9. SCHEJBAL, V. Czech radar technology. IEEE Trans. on Aerospace and Electronics Systems, 1994, vol. 30, no. 1, p. 2 - 17.
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Keywords: Antenna gain, antenna beam width, doubly curved reflector, estimation of antenna gain, electromagnetic compatibility (EMC)

P. Hazdra, P. Hamouz [references] [full-text] [Download Citations]
On the Modal Superposition Lying under the MoM Matrix Equations

This paper shows an interesting sight on the correspondence between total current solution obtained by the Method of Moments and by the Characteristic modes respectively. Derivation is based on representation of a matrix in its spectral form. Detailed study of dipole antenna fed under different conditions is presented demonstrating that modal decomposition of currents offers a nice physical insight into behavior of radiating structures.

  1. HARRINGTON, R. F. Field Computation by Moment Methods, Wiley IEEE Press, 1993.
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  5. RICHARDSON, M. Modal mass, stiffness and damping, http://www.altracustica.org/docs/paper31.pdf
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Keywords: Method of moments, characteristic modes, matrix operator, spectral factorization, modal superposition

M. Pokorny, Z. Raida [references] [full-text] [Download Citations]
Modeling of Microwave Semiconductor Diodes

The paper deals with the multi-physical mode-ling of microwave diodes. The electrostatic, drift-diffusion and thermal phenomena are considered in the physical model of the components. The basic semiconductor equati-ons are summarized, and modeling issues are discussed. The simulations of the Gunn Effect in transferred electron devices and the carrier injection effect in PIN diodes are investigated and discussed. The analysis was performed in COMSOL Multiphysics using the finite element method.

  1. SELBERHERR, S. Analysis and Simulation of Semiconductor Devi-ces. Hiedelberg: Springer-Verlag, 1984.
  2. COMSOL Multiphysics Model Library. Stockholm: COMSOL, 2006.
  3. KRAMER, K. M., HITCHON, W. N. G. Semiconductor Devices: Simulation Approach. Englewood Cliffs: Prentice Hall, 1997.
  4. QUAY, R. Analysis and Simulation of High Electron Mobility Tran-sistors [online]. Ph.D. Thesis. Vienna: Vienna University of Techno-logy. Available: http://www.iue.tuwien.ac.at/phd/quay/diss2.html
  5. TAYLOR, G. C., ROSEN, A., FATHY, A. E., SWAIN, P. K., PER-LOW, S. M. Surface PIN Device. U.S. Patent US 6617670B2, 2003.

Keywords: Gunn effect, carrier injection effect, PIN, FEM, COMSOL Multiphysics, drift-diffusion scheme, multi-physical model

P. Bezousek, V. Schejbal [references] [full-text] [Download Citations]
Bistatic and Multistatic Radar Systems

Radar systems, based on bistatic radar concept attracted a substantial attention in the recent years. Passive coherent location systems using \"transmitters of opportunity\" like radio or TV broadcasters, GSM base stations, satellite communication and GNSS signals proved their potential in detection and tracking moving targets over a significant area. In this paper the multistatic location system with non-cooperative transmitters is described and various aspects of signal processing and signal parameters are discussed.

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  9. GRIFFITHS, H. D., BAKER, C. J. Passive coherent location radar systems. Part I: Performance prediction. IEE Proc. Radar, Sonar Navigation, 2005, vol. 152, no. 3, p. 153 – 159.
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  11. GUNER, A., TEMPLE, M.A., CLAYPOO, JR., R.L. Direct path filtering of DAB waveform PCL receiver target channel. Electronic Letters, 2003, vol. 39, no. 1, p. 118 – 119
  12. TAN, D.K.P., SUN, H., LU, Y., LESTURGIE, M., CHAN, H. L. Passive radar using Global System for Mobile communication signal: theory, implementation and measurements. IEE Proc. of Radar and Sonar Navig., 2005, vol. 152, no. 3, p. 116-123.
  13. HOWLAND, P. E., MAKSIMJUK, D., REITSMA, G. FM radiobased bistatic radar. IEE Proc. of Radar and Sonar Navig., 2005, vol. 152, no. 3, p. 1007-1016.
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  15. POULIN, D. Passive detection using digital broadcasters (DAB, DVB) with COFDM modulation. IEE Proc. of Radar and Sonar Navig., 2005, vol. 152, no. 3, p. 143-152.
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  17. SAINI, R., CHERNIAKOV, M. DTV signal ambiguity function analysis for radar application. IEE Proc. of Radar and Sonar Navig., 2005, vol. 152, no. 3, p. 133-142.
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  19. HE, X., CHERNIAKOV, M., ZENG, T. Signal detectability in SSBSAR with GNSS non-cooperative transmitter. IEE Proc. of Radar and Sonar Navig., 2005, vol. 152, no. 3, p. 124-132.
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Keywords: Radar, bistatic, multistatic, coherent, positioning, signal processing

R. Urban, S. Zvanovec [references] [full-text] [Download Citations]
Dispersion and Pulse Interferences Investigation for UWB Signal Propagation

The Ultra WideBand (UWB) technology utilizing nanosecond pulses has been one of the main phenomena in communications and radar applications for several years. This paper discusses the basic measurement techniques of impulse systems, particularly focusing on the dispersion and pulse interferences of the UWB propagation channel. Propagation aspects of two-ray approach are investigated in depth, using both measurements and simulations.

  1. GHARPUREY, R., KINGET, P. Ultra Wideband Circuits, Transceivers and Systems. New York: Springer, 2008.
  2. http://www.pulselink.net/technology/cwave_tech.htm
  3. SIWIAK, K., MCKEOWN, D. Ultra-Wideband Radio Technology. West Sussex: John Wiley & Sons, 2004.
  4. GHAVAMI, M., MICHAEL, L. B., KOHNO, R. Ultra Wideband Signals and Systems in Communication Engineering. West Sussex: John Wiley & Sons, Ltd, 2004.
  5. The Federal Communications Commission FCC, http://www.fcc.gov
  6. Decision of Commission of the European Communities of 21/II/2007, on allowing the use of the radio spectrum for equipment using ultra-wideband, http://ec.europa.eu
  7. HANEDA, K., TAKADA, J., KOBAYASHI, T. A parametric UWB propagation channel estimation and its performance validation in an anechoic chamber. IEEE Transactions on Microwave Theory and Techniques, 2006, vol. 54, no. 4 , Part 2, pp. 1802 – 1811.
  8. http://www.antennasvce.org/Community/Education/Courses/Locations
  9. PECHAC, P., KLEPAL, M., NOVOTNY, K. Novel approach to indoor propagation modeling. Radioengineering, 2000, vol. 9, no. 3, p. 12-16. ISSN 1210-2512.
  10. TESAR, R. Generator for Ultra-wideband Applications. Diploma thesis, Department of Electromagnetic Field, CTU in Prague, 2007 (in Czech).
  11. PIKSA, P., SOKOL, V. Small Vivaldi antenna for UWB. In Proceedings of the Conference Radioelektronika. Brno (Czech Republic), 2005, p. 490-493.
  12. MOLLISCH, A. F. Ultrawideband propagation channels – theory, measurement, and modeling. IEEE Transactions on Vehicular Technology, 2005, vol. 54, no. 5, p. 1528-1545.
  13. CRAMER, R. J.-M., SCHOLTZ, R. A., WIN, M. Z. Evaluation of an ultra-wide-band propagation channel. IEEE Transactions on Antennas and Propagation, 2002, vol. 50, no. 5, pp. 561-570.
  14. MANTEUFFEL, D. Modeling and visualization of the communication link for UWB consumer applications. In Loughborough International Conference on Antennas and Propagation, 2007.
  15. URBAN, R. Specifics of UWB Propagation in Nanocells. Diploma thesis, Department of Electromagnetic Field, CTU in Prague, 2008 (in Czech).
  16. MONICH, U. J., STURM, C., BOCHE, H., WIESBECK, W. Empirical capacity and the fading characteristics of ultra-wideband indoor propagation channels. In Radio and Wireless Symposium, 2008 IEEE , pp.607-610, 2008.

Keywords: UWB, Ultra Wideband, two-ray propagation model

J. Mikulka, S. Hanus [references] [full-text] [Download Citations]
Bluetooth and IEEE 802.11b/g Coexistence Simulation

This paper deals with the coexistence simulation of Bluetooth and Wi-Fi physical layers. Bluetooth and Wi-Fi systems share the same ISM 2.4 GHz frequency band and therefore using both systems in the same area may cause interference. A model of Bluetooth and IEEE 802.11b/g physical layers was made in Mathworks Matlab Simulink environment. A new simulation of Bluetooth and Wi-Fi coexistence is presented. The results in graphical form are introduced as a dependence of BER on Eb/N0 and BER on power ratio of Bluetooth and Wi-Fi systems.

  1. IEEE Std 802.11-2007. Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications., URL .
  2. IEEE Std 802.15.2-2003. Part 15.2: Coexistence of Wireless Personal Area Networks with Other Wireless Devices Operating in Unlicensed Frequency Bands., URL .
  3. Bluetooth Special Interest Group. Specification of the Bluetooth system, version: 2.1 + EDR., URL , July 26, 2007.
  4. MatlabCentral. An open exchange for the MATLAB and Simulink community. URL .
  5. MIKULKA, J., HANUS, S. Bluetooth EDR physical layer modeling. In Proceedings of the 18th International Conference Radioelektronika 2008. Brno (Czech Republic), 2008, p. 97-100. ISBN: 978-1- 4244-2087-2.
  6. MIKULKA, J., HANUS, S. Complementary code keying implementation in the wireless networking. In Conference Proceedings, Maribor (Slovenia), 2007, p. 329-332. ISBN: 978-961-248-029-5.
  7. TRANTER,W. H., SHANMUGAN, K. S., RAPPAPORT, T. S. Principles of Communication Systems Simulation with Wireless Applications. Prentice Hall PTR. (January 9, 2004), 2004, ISBN: 978- 0134947907.
  8. STAVROULAKIS, P. Interference Analysis and Reduction for Wireless Systems. Artech House Publishers, 2003. 407 p. ISBN: 1-58053-316-7.
  9. PROAKIS, J. G. Digital Communications. McGraw Hill Higher Education; 4New Ed edition, 2000. 1024 p. ISBN: 978-0072321111.

Keywords: Bluetooth, Wi-Fi, IEEE 802.11b, IEEE 802.11g, Coexistence

F. Gleissner, S. Hanus [references] [full-text] [Download Citations]
Co-channel and Adjacent Channel Interference Measurement of UMTS and GSM/EDGE Systems in 900 MHz Radio Band

This paper is concerned with inter-system and intra-system interference measurements of 2.5G and 3G mobile communication systems. The both systems UMTS and GSM/EDGE are assumed to operate in a common radio band of 900 MHz. The main system parameters are briefly introduced as well as the measurement scenario. Several simulations and key measurements were performed. Important results are described and commented along with a graphical representation, namely bit error ratio (BER) dependence on carrier to noise ratio (CNR) in the presence of additive white Gaussian noise (AWGN), the measurement of adjacent channel interference ratio of each system, the coexistence of both systems in same band and the impact of a carrier offset on BER.

  1. KRUGER, R., MELLEIN, H. UMTS: Introduction and Measurement. Rohde&Schwarz GmbH&Co. KG, Germany, 2004.
  2. LAIHO, J., WACKER, A., NOVOSAD, T. Radio Network Planning and Optimisation for UMTS. John Wiley & Sons Ltd, 2005. ISBN 0- 470-01575-6.
  3. ETSI, Technical Specification 125 101 (3GPP TS 25.101), Universal Mobile Telecommunications System (UMTS); User Equipment (UE) Radio Transmission and Reception (FDD), v7.2.0.
  4. ISCO International Technology and Systems Group. Optimization of the Spectral Efficiency of 900 MHz Codeployments of UMTS and GSM. Technical brief, November 2007. ISCO International.
  5. HOLMA, H., TOSKALA, A. WCDMA for UMTS: Radio Access for Third Generation Mobile Communications. John Wiley & Sons Ltd, England, 2005. ISBN 0-470-87096-6.
  6. SEURRE, E., SAVELLI, P., PIETRI, P.-J. EDGE for Mobile Internet. Artech House Publishers, 2003. ISBN 1-58053-597-6.
  7. ETSI, Technical Specification 100 573 (3GPP TS 05.01), Digital Cellular Telecommunications System; Physical Layer on the Radio Path, v8.9.0.
  8. ETSI, EN 300 908 (GSM 05.02), Digital Cellular Telecommunications System; Multiplexing and Multiple Access on the Radio Path, v8.5.1.
  9. ETSI, Technical Specification 100 909 (3GPP TS 05.03), Digital Cellular Telecommunications System; Channel Coding, v8.9.0 (2005-01).
  10. 3GPP, Technical Specification 05.04, Digital Cellular Telecommunications System; Modulation, v8.3.0.
  11. 3GPP, Technical Specification 25.212, Multiplexing and Channel Coding (FDD), v5.4.0.
  12. COST 231, Final report. Digital Mobile Radio Towards Future Generation Systems.
  13. GLEISSNER, F., HANUS, S. The comparison of GSM-EDGE signal transmission over AWGN and Rayleigh fading channel. In Proceedings of the 18th International Conference Radioelektronika 2008. Praha, Czechoslovakia Section IEEE. p. 109 - 112. ISBN 978- 1-4244-2087-2.
  14. GLEISSNER, F., RUZICKA, Z., HANUS, S. UMTS - Impact of channel coding on BER. In Proceedings of the 15th International Electrotechnical and Computer Science Conference ERK 2007. 16(1), p. 136 - 139. ISSN 1581-4572.

Keywords: UMTS, GSM/EDGE, interference, measurement, cochannel, adjacent channel, BER, carrier offset

V. Wieser, V. Psenak [references] [full-text] [Download Citations]
Performance of Advanced Hybrid Link Adaptation Algorithms in Mobile Radio Channel

The fast power adaptation is essential for WCDMA based mobile radio networks, as 3G UMTS. Although the first version of UMTS has been released in 1999 (Release 99) evolution was not finished yet. Quality of Service (QoS) and user data rate (e.g. HSDPA and HSUPA) are continuously increasing from release to release. Even though link adaptation frequency (1500 times per second) seems to be enough to span accidental fadings of mobile radio channel, used link adaptation algorithm is based on non-actual information about mobile radio channel state, which causes transmitter reaction delay to the actual channel state. Usage of appropriate prediction method to estimate near future channel state seems to be a valuable step to improve hybrid link adaptation algorithm. In this article we have described and simulated the new SIR-slot based advanced link adaptation algorithms. Algorithms were designed to increase efficiency of data transmission among a user equipment and base stations (uplink) for different simulation environments (pedestrian channel with mobile subscriber speed 5 km/h, 15 km/h and vehicular channel with speed 45 km/h).

  1. EKMAN, T. Prediction of Mobile Radio Channels – Modeling and Design. Dissertation for the degree of Doctor of Philosophy in Signal Processing at Uppsala University, Sweden, 2002, ISBN 91-506- 1625-0.
  2. EKMAN, T. Prediction of Mobile Radio Channels. PhD thesis, Uppsala University, Sweden, 2001.
  3. PSENAK, V., WIESER, V. High speed downlink packed access in UMTS network. Advances in Electrical Engineering. University of Zilina. 2005, vol. 4, no. 1, pp. 8-13, ISSN 1336-1376.
  4. HOLMA, H., TOSKALA, A. HSDPA / HSUPA for UMTS. Wiley, 2001. ISBN: 0-470-01888-4
  5. WIESER, V., PSENAK, V. Analysis of mobile radio channel prediction methods. Science & Military journal, 2007, vol. 2, no. 2, pp.42-45. The Academy of the Armed Forces of General Milan Rastislav Stefanik, Demanova 393, 031 01 Liptovsky Mikulas, Registered No: 3487/2005, ISSN 1336-8885
  6. WIESER, V., PSENAK, V. WCDMA Mobile radio network simulator with hybrid link adaptation. Advances in Electrical Engineering. University of Zilina. 2005, vol. 4, no. 3, pp. 200-205. ISSN 1336-1376.
  7. WIESER, V., PSENAK, V. BER and SIR based hybrid link algorithms performance in mobile radio channel. Radioenginnering 2005, vol. 14, no.4, p. 81-86. ISSN 1210-2512.
  8. CASTRO, P. J. The UMTS Network and Radio Access Technology – Air Interface Techniques for Mobile Systems. Wiley, 2001, ISBN 0 471 81375 3.
  9. WIESER,V., PSENAK,V. Data rate increasing for high speed multimedia services in enhanced WCDMA mobile radio network. In IWSSIP 2006, 13th International Conference on Systems, Signals and Image Processing. Budapest (Hungary), 2006, pp.75-78, ISBN 80-89082-09-2.
  10. 3GPP TS 25.213 V6.2.0 (2005-03). Spreading and Modulation (FDD).
  11. ETSI TR 101 112 V3.2.0. (1998-04). Selection Procedures for the Choice of Radio Transmission Technologies of the UTMS.
  12. 3GPP TS 25.212 V6.4.0 (2005-03). Multiplexing and Channel Coding (FDD).
  13. WIESER,V., PSENAK,V. Performance of hybrid link adaptation algorithm with prediction of mobile radio channel state. In TPS 2007, 30th International Conference on Telecommunications and Signal Processing. Brno (Czech Republic), 2007, pp.32-35, ISBN 978-80- 214-3445-5.

Keywords: Next generation mobile networks, link adaptation algorithm, prediction methods, uplink data transmission efficiency, hybrid adaptation

R. R. A. Oni [references] [full-text] [Download Citations]
Preamble Design Problematic with 802.11a IEEE Standard (Minn’s Training Sequence Approach)

Generally OFDM systems use a predefined signal pattern, called preamble [2] [3], which helps the receiver to achieve a better signal detection (coarse, fine time synchronization) with the frequency offset and channel estimation. In most of the time having all these conditions fulfilled the receiver achieves relatively a good performance while keeping as low as possible the total consuming power and the BER (Bite Error Rate).
This paper presents the results obtained while combining a part of the preamble [2] [3] and the Minn\'s training sequence. We have got interesting performance results comparable to those results obtained for the relatively new standard 802.16a.

  1. SCHMIDL, T. M., COX, D. C. Robust frequency and timing synchronization for OFDM. IEEE Transactions on Communications, 1997, vol. 45, no. 12, pp. 1613 – 1621. Digital Object Identifier 10.1109/26.650240.
  2. http://standards.ieee.org/getieee802/download/802.11-1999.pdf, 2007-06-15.
  3. HLAING MINN; AL-DHAHIR, N. Training signal design for MIMO OFDM channel estimation in the presence of frequency offsets. In Wireless Communications and Networking Conference. 2005 IEEE, vol. 1, 13-17 March 2005, pp. 1 – 6. Digital Object Identifier 10.1109/WCNC.2005.1424466
  4. http://www.wimaxforum.org/technology/downloads/WiMAXWhitep aper.pdf, 2007-06-15.

Keywords: OFDM, 802.11a, WiFi, WiMax, LAN, preamble design, IDFT/ DFT, FFT

S. G. Pleshkova-Bekiarska [references] [full-text] [Download Citations]
Joint Source-Channel CELP Coding

The method of speech coding CELP is extensively used in much voice communication-, multimedia-, video conference and other systems. There are a lot of papers related to CELP coding characteristics improvement for a better speech quality after decoding. Most of the papers are dedicated to lower the rate of CELP coded speech transmission. One problem related to low rate CELP speech transmission with a good speech decoding quality is noising in the channel for transmission. The goal of this paper is to combine the advantages and the possibilities of CELP speech coding to reduce the rate of transmission and the methods of channel coding to protect the most important CELP coding parameters in each speech frame such as line prediction coefficients, excitation indexes etc.

  1. SHANNON, C. A mathematical theory of communication. Bell Sys. Tech. Journal, 1948, vol. 27, p. 379-423.
  2. CAMPBELL, J., TREMAN, T. The federal standard 1016 4800 bps CELP voice coder. Digital Signal Processing, Academic Press, 1991, vol.1, no.3, p.145-155.
  3. HAGENAUER, J. Rate-compatible punctured convolutional codes (RCPC Codes) and their applications. IEEE Transactions on Communications, 1988, vol. 36, no. 4, p.389-400.
  4. MILETIEV, R., ARNAUDOV, R. Spectrum analysis of nonuniformly sampled data for radar applications. Frequenz, 2007, vol. 61, no. 3-6, p. 128-132.
  5. PLESHKOVA, S., MOMCHEDJIKOV, M. Fast CELP code book search method. In Proc. of the Int. Sci. Conf. on Energy and Information Syst. and Technol. Sofia (Bulgaria), 2003, p.178-182.

Keywords: Source-channel Coding, CELP Coding, Speech coding, Speech Processing

T. Kratochvil, R. Stukavec [references] [full-text] [Download Citations]
DVB-T Digital Terrestrial Television Transmission over Fading Channels

The paper deals with the transmission of the digital television signal according to the DVB-T standard in SFN network over fading channels for the fixed reception. The laboratory transmission system for the real broadcasting based on R&S RF test and measuring equipments is presented including the transmission parameters setup. The results of broadcasting over Gausian, Ricean and Rayleigh channels and results of the echo impairments are presented and discussed with the theory and simulation results. The BER before and after Viterbi decoding and according to MER equal to S/N ratio in the channel from the constellation diagram were compared in all transmission experiments. Additional picture quality evaluation is presented using DVQL-W metric that monitors blockiness structures in MPEG-2 compressed pictures and gives notice of known \"cliff-off\" effect.

  1. REIMERS, U. Digital Video Broadcasting, The Family of International Standards for Digital Television. 2nd ed. Berlin: Springer Verlag, 2004. ISBN 3-540-43545-X.
  2. FISHER, W. Digital Television. A Practical Guide for Engineers. 1st ed. New York: Springer-Verlag, 2004. ISBN 3-540-01155-2.
  3. ETSI EN 300 744 V1.4.1 (2001-01). European Standard. Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for DTT. ETSI, 2001.
  4. ETSI TR 101 290 V1.2.1 (2001-05). Technical report. Digital Video Broadcasting (DVB); Measurement guidelines for DVB systems. ETSI, 2001.
  5. Rohde & Schwarz. Operating Manual. Broadcast Test System R&S SFU. Model 2110.2500.02. Rohde&Schwarz, 2005.
  6. Rohde & Schwarz. Operating Manual. Digital Video Quality Analyzer R&S DVQ. Model 2079.6003.03. Rohde&Schwarz, 2005.

Keywords: Digital Terrestrial Transmission, Gaussian channel, Ricean channel, Rayleigh channel, DVQL, DVB-T

M. Slanina, V. Ricny [references] [full-text] [Download Citations]
Estimating PSNR in High Definition H.264/AVC Video Sequences Using Artificial Neural Networks

The paper presents a video quality metric designed for the H.264/AVC codec. The metric operates directly on the encoded H.264/AVC bit stream, parses the encoding parameters and processes them using an artificial neural network. The network is designed to estimate peak signal-to-noise ratios of the video sequence frames, thus enabling computation of full reference objective quality metric values without having the undistorted video material prior to encoding for comparison. We present the metric framework and test its performance for LDTV (low definition television) as well as HDTV (high definition television) video material.

  1. WINKLER, S. Digital Video Quality: Vision Models and Metrics. Chichester: Wiley, 2005.
  2. WU, H. R., RAO, K. R. Digital Video Image Quality and Perceptual Coding. Boca Raton: Taylor & Francis, 2006.
  3. WANG, Z., LU, L., BOVIK, A. C. Video quality assessment based on structural distortion measurement. Signal Processing: Image Communication, February 2004, vol. 19, no. 2, p. 121-132.
  4. WANG, Z., BOVIK, A. C., EVANS, B. L. Blind measurement of blocking artifacts in images. In Proceedings of 2000 International Conference on Image Processing, vol. 3, p. 981-984, 2000.
  5. EDEN, A. No-reference estimation of the coding PSNR for H.264- coded sequences. IEEE Transactions on Consumer Electronics, May 2008, vol. 53, no. 2, p. 667-674.
  6. ITU-T Recommendation H.264, Advanced Video Coding for Generic Audiovisual Services. Geneva: The International Telecommunication Union, 2006.
  7. SUEHRING, K. The H.264/MPEG-4 AVC reference software – JM11. [online] Available: http://iphome.hhi.de/suehring/tml/download/
  8. Arizona State University, Video Traces Research Group. CIF Sequences. [online] Available: http://trace.eas.asu.edu/yuv/cif.html
  9. HAGLUND, L. The SVT High Definition Multi Format Test Set. Sveriges Television AB, 2005 [online] Available: http://www.ebu.ch/en/technical/hdtv/test_sequences.php
  10. DEMUTH, H., BEALE, M. Neural Network Toolbox for Use With MATLAB. User’s Guide, version 4. Natick: Mathworks, Inc., 2000.

Keywords: H.264/AVC, video quality, objective quality metric, HDTV, artificial neural network

R. Kolar, J. Jan [references] [full-text] [Download Citations]
Detection of Glaucomatous Eye via Color Fundus Images Using Fractal Dimensions

This paper describes a method for glaucomatous eye detection based on fractal description, followed by classification. Two methods for fractal dimensions estimation, which give a different image/tissue description, are presented. The fundus color images are used, in which the areas with retinal nerve fibers are analyzed. The presented method shows that fractal dimensions can be used as features for retinal nerve fibers losses detection, which is a sign of glaucomatous eye.

  1. PELI, E., HEDGES, T. R., SCHWARTZ, B. Computer measurement of the retina nerve fiber layer striations. Applied Optics, 1989, no. 28, p. 1128 - 1134.
  2. LEE, S. Y., KIM, K. K., SEO, J. M., KIM, D. M., CHUNG, H., PARK, K. S., KIM, H. C. Automated quantification of retinal nerve fiber layer atrophy in fundus photograph. In 26th Annual International Conference of the IEEE IEMBS. San Francisco (USA), 2004, vol. 1, p. 1241 – 1243.
  3. OLIVA, A. M., RICHARDS, D., SAXON, W. Search for colordependent nerve-fiber-layer thinning in glaucoma: A pilot study using digital imaging techniques. ARVO meeting, Fort Lauderdale (USA), 2007, e-Abstract 3309. [Online] cited 08-08-2008. Available at http://www.arvo.org.
  4. TORNOW, R. P., LAEMMER, R., MARDIN, C. Quantitative imaging using a fundus camera. ARVO meeting. Fort Lauderdale (USA), 2007, e-Abstract 1206. [Online] cited 08-08-2008. Available at http://www.arvo.org.
  5. BUDENZ, D. L. Reproducibility of retinal nerve fiber thickness measurements using the stratus OCT in normal and glaucomatous eyes. Investigative Ophthalmology and Visual Science, 2005, vol. 46, p. 2440 – 2443.
  6. JANKNECHT, P., FUNK, J. Optic nerve head analyser and Heidelberg retina tomograph: accuracy and reproducibility of topographic measurements in a model eye and in volunteers. British Journal of Ophthalmology, 1994, vol. 78, p. 760 – 768.
  7. HOFFMAN, E. M. et.al. Glaucoma detection using the GDx nerve fibre analyzer and the retinal thickness analyzer. European Journal of Ophthalmology, 2006, vol. 16, p. 251 – 258.
  8. BARNELEY, M. F., DEVANEY, R. L., MANDELBROT, B. B. The Science of Fractal Images. New York: Springer-Verlag, 1988.
  9. CARDINAL, J. Fast fractal compression of greyscale images. IEEE Transaction on Image Processing, 2001, vol. 10, no. 1, p. 159 – 164.
  10. HARTENSTEIN, H., RUHL, M., SAUPE, D. Region-based fractal image compression. IEEE Transactions on Image Processing, 2000, vol. 9, no. 7, p. 1171 – 1184.
  11. CHANG, R. F., CHEN, CH. J., HO, M. F., CHEN, D.-R., MOON, W. K. Breast ultrasound classification using fractal analysis. In Proceedings of the Fourth IEEE Symposium on Bioinformatics and Bioengineering. Taichung (Taiwan), 2004, pp. 100-107.
  12. CHARALAMPIDIS, D., PASCOTTO, M., KERUT, E. K. LINDNER, J. R. Anatomy and flow in normal and ischemic microvasculature based on a novel temporal fractal dimension analysis algorithm using contrast enhanced ultrasound. IEEE Transactions on Medical Imaging, 2006, vol. 25, no. 8, p. 1079 to 1086.
  13. PESQUET-POPESCU, B., VEHEL, J. L. Stochastic fractal models for image processing. IEEE Signal Processing Magazine, 2002, vol. 19, no. 5, p. 48 – 62.
  14. CHENG, S. CH., HUANG, Y. M. A novel approach to diagnose diabetes based on the fractal characteristics of retinal images. IEEE Transactions on Information Technology in Biomedicine, 2003, vol. 7, no. 3, p. 163 – 170.
  15. BERNDT-SCHREIBER, M. Fractal based approaches to morphological analysis of fundus eye images. Advances in Soft Computing, Springer, 2005, vol. 30, p. 477 – 484.
  16. PETROU, M., SEVILLA, P. G. Image processing: Dealing with Texture. Wiley Publishing, 2006.
  17. TURNER, M. J., BLACKLEDGE, J. M., ANDREWS, P. R. Fractal Geometry in Digital Imaging. Academic Press, 1998
  18. LAEMMER, R., KOLAR, R., JAN, J., MARDIN, C. Y. Impact of parapapillary autofluorescence in glaucoma – clinical aspects. In Analysis of Biomedical Signals and Images. Biosignal 2008, Brno (Czech Republic), CD-ROM proceedings, 2008, 5 pages. ISSN 1221-412X.
  19. DUDA, R. O., HART, P. E., STORK, D. Pattern Classification, New York: John Wiley & Sons, 2000.
  20. SCHOLKOPF, B., SMOLA, A. J. Learning with Kernels. Support Vector Machines, Regularization, Optimization and Beyond., Cambridge, MA: MIT Press, 2002.
  21. KOLAR, R., URBANEK, D., JAN, J. Texture based discrimination of normal and glaucomatous retina. In Analysis of Biomedical Signals and Images. Biosignal 2008, Brno (Czech Republic), CDROM proceedings, 5 pages, 2008. ISSN 1221-412X.
  22. CHANG, CH. CH., LIN, CH. J. LIBSVM - A Library for Support Vector Machines. URL: .
  23. TUULONEN, A. et al. Digital imaging and microtexture analysis of the nerve fibre layer. Journal of Glaucoma, 2000, vol. 9, p. 5 – 9.
  24. JENNANE, R., OHLEY, W. J., MAJUMDAR, S., LEMINEUR, G. Fractal analysis of bone x-ray tomographic microscopy projections. IEEE Transaction on Medical Imaging, 2001, vol. 20, p. 443-449.
  25. ZOOK, J., IFTEKHARUDDIN, K. Statistical analysis of fractalbased brain tumor detection algorithms. Magnetic Resonance Imaging, 2005, vol. 23 , no. 5, p. 671 – 678.
  26. BOCK, R., MEIER, J., MICHELSON, G., NYUL, L., G. HORNEGGER, J. Classifying glaucoma with image-based features from fundus photographs. Lecture Notes in Computer Science, Springer, 2007, vol. 4713, p. 355 – 365.
  27. GAZAREK, J., JAN, J., KOLAR, R. Detection of neural fibre layer in retina images via textural analysis. In Analysis of Biomedical Signals and Images. Biosignal 2008, Brno (Czech Republic), CDROM proceedings, 7 pages, 2008. ISSN 1221-412X.

Keywords: Fractal, texture analysis, feature description, classification, glaucoma, retina

M. Oravec, B. Kristof, M. Kolarik, J. Pavlovicova [references] [full-text] [Download Citations]
Extraction of Facial Features from Color Images

In this paper, a method for localization and extraction of faces and characteristic facial features such as eyes, mouth and face boundaries from color image data is proposed. This approach exploits color properties of human skin to localize image regions – face candidates. The facial features extraction is performed only on preselected face-candidate regions. Likewise, for eyes and mouth localization color information and local contrast around eyes are used. The ellipse of face boundary is determined using gradient image and Hough transform. Algorithm was tested on image database Feret.

  1. KAKUMANU, P., MAKROGIANNIS, S., BOURBAKIS, N. A survey of skin-color modeling and detection methods. Pattern Recognition, 2007, vol. 40, p. 1106 – 1122.
  2. YANG, M. H., KRIEGMAN, D. E., AHUJA, N. Detecting Faces in Images: A Survey. IEEE Tranactions on Pattern Analysis and Machine Intelligence, 2002, vol. 24, no. 1, p. 34-58.
  3. SANDEEP, K., RAJAGOPALAN, A. N. Human face detection in cluttered color images using skin color and edge information. In Proceedings of the Indian Conference on Computer Vision, Graphics and Image Processing (ICVGIP'02). Ahmedabad (Dec. India), 2002, p. 230-235.
  4. REIN-LIEN, HSU K., MOHAMED, ABDEL-MOTTALEB, ANIL K. JAIN. Face detection in color images. IEEE Transactions on Pattern Analysis and Machine Intelligence, 2002, vol. 24, p. 696 to 706.
  5. PHUNG, S. L., BOUZERDOUM, A., CHAI, D. Skin segmentation using color pixel classification: analysis and comparison. IEEE Transactions on Pattern Analysis and Machine Intelligence, 2005, vol. 27, no. 1, p. 148-154.
  6. HERODOTOU, N., PLATATONIS, K. N., VENETSANOPOULOS, A. N. Image Processing Techniques for Multimedia Processing. CRC Press, Boca Raton, Florida, 2000, p. 97-127, ISBN 0-8493- 3492-6.
  7. JACKWAY, P. T., DERICHE, M. Scale-space properties of the multiscale morphological dilation-erosion. IEEE Transactions on Pattern Analysis and Machine Intelligence, 1996, vol. 18, p. 38-51.
  8. WAQAR, M., NOMAN, A., CHUNG-TSE MAR Face Detection Project, 2003, http://www.stanford.edu/~wmohsin/ee368group10.pdf
  9. FERET Database, http://www.itl.nist.gov/iad/humanid/colorferet/ home.html, NIST, 2003.
  10. FISCHER, R., PERKINS, S., WALKER, A., WOLFART, E. Hough Transform, University of Edinburgh UK 2003, http://homepages.inf.ed.ac.uk/rbf/HIPR2/hough.htm.
  11. LEI, Y., WONG, K. C. Ellipse detection based on symmetry. Nanyang Technological University, Singapore, Pattern Recognition Letters 20 1999, p. 41-47.

Keywords: Skin color segmentation, face detection, facial features extraction, morphological operations, ellipse detection, Hough transform, Feret database

P. Stranak [references] [full-text] [Download Citations]
Interfering DC Component, Suppression and Influence to Digital Signal Processing

The article concentrates on effects of a digitized audio signal DC component on a typical A/D converter and its influence on further signal processing. This article analyses reasons of the interfering DC component emergence in the A/D converter. Results of the measurement made on Analog Devices converter are presented. The DC component can adversely affect a series of signal processing algorithms such as algorithms for maintaining stable level of signal (e.g. leveler algorithm). The article examines the possibility of a DC component removal by digital filtering. Attention is focused on the choice of a suitable filter type and its parameters in order to avoid any destruction of a transmitted signal, e.g. due to poor group delay characteristic, or by suppressing low frequencies in the filter.

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Keywords: DC component, A/D converter, audio digital signal processing, DSP, digital filtering, FIR, IIR