# December 2003, Volume 12, Number 4

**J. Dobes**
[references] [full-text]

An Accuracy Comparison of the Digital Filter Poles-Zeros Analysis

In the paper, a comparison of MATLAB and CIA procedures for computing the poles and zeros of digital filters is performed. The accuracy of both tools is tested using finite impulse response filters of a higher order - the first was designed by "remez" algorithm and the second came from the area of psychoacoustics.

- RUBNER-PETERSEN, T. On sparse matrix reduction for computingthe poles and zeros of linear systems, In Proceedings of the 4thInternational Symposium on Network Theory. Ljubljana, 1979.
- DOBES, J., MICHAL, J. Using the variable-length arithmetic for anaccurate poles-zeros analysis. Radioengineering, 2003, vol. 12,no. 3, p. 1 - 5.
- MITRA, S. K., KAISER, J. F. Handbook for digital signal processing.New Jersey: John Wiley & Sons, 1993.
- LOBOVSKY, J. Digital psychoacoustic filter design. MastersThesis, Czech Technical University in Prague, Dept. of RadioElectronics, 2001.
- BIOLEK, D. Secondary root polishing techniques in computercircuit analysis. In Proceedings of the Radioelektronika'99. Brno(Czech Republic), 1999, p. 42 - 45.
- DOBES, J. An accurate poles-zeros analysis for large-scale analogand digital circuits. In Proceedings of the IEEE InternationalConference on Electronics, Circuits and Systems. St.Julians (Malta),2001, p. 1027 - 1030.

**L. Brancik**
[references] [full-text]

Utilization of MATLAB in Simulation of Linear Hybrid Circuits

In the paper a MATLAB-based method for simulating transient phenomena in linear hybrid circuits containing parts with both lumped and distributed parameters is presented. Distributed parts of the circuit are multiconductor transmission lines, which can generally be nonuniform, with frequency-dependent parameters, and under nonzero initial voltage and/or current distributions. In principle a solution is formulated using the modified nodal analysis method in the frequency domain. Subsequently an improved fast method of the numerical inversion of Laplace transforms in the vector or matrix form is applied to obtain solution in the time domain.

- LUM, S., NAKHLA, M. S., ZHANG, Q. J. Sensitivity Analysis of Lossy Coupled Transmission Lines. IEEE Trans. on Microwave Theory and Techniques, 1991, vol. 39, no. 12, p. 2089-2099.
- CHIPROUT, E., NAKHLA, M. S. Asymptotic Waveform Evaluation and Moment Matching for Interconnect Analysis. Carleton University, Kluwer Academic Publisher, Boston, 1994.
- BRANCIK, L. Time-Domain Simulation of Multiconductor Transmission Line Systems under Nonzero Initial Conditions. In Proc.of the 15th ECCTD'01. Espoo, Finland, 2001, vol. 1, p. 73-76.
- BRANCIK, L. Time-Domain Simulation of Nonuniform Multicon-ductor Transmission Lines under Nonzero Initial Conditions Using Matlab Language. In Proc. of the 14th ECCTD´99. Stresa, Italy, 1999, vol. 2, p. 1135-1138.
- PAUL, C. R. Analysis of Multiconductor Transmission Lines. John Wiley & Sons, New York, 1994.
- GANTMACHER, R The Theory of Matrices. Chelsea, N.York, 1977.
- BRANCIK, L. Utilization of Quotient-Difference Algorithm in FFT-based Numerical ILT Method. In Proc. 11th Radioelektronika'2001. Brno, Czech Republic, 2001, p. 352-355.
- HENRICI, P. Quotient-Difference Algorithms, Math. Methods for Digital Computers. Eds. A. Ralston and H. S. Wilf, John Wiley & Sons, New York, 1967, vol. 2, p. 37-62.
- BRANCIK, L. Improved Numerical Inversion of Laplace Transforms Applied to Simulation of Distributed Circuits. In Proc. XI. ISTET01. Linz, Austria, 2001, p. 51-54.
- BRANCIK,L. Matlab Oriented Matrix Laplace Transforms Inversion for Distributed Systems Simulation. In CD ROM Proc. of 12th Radioelektronika'2002. Bratislava, Slovakia, 2002, paper no. 114.

**N. Kostov**
[references] [full-text]

Mobile Radio Channels Modeling in MATLAB

In this paper, a MATLAB based approach for mobile radio channels modeling is presented. Specifically, the paper introduces the basic concepts for modeling flat fading channels in MATLAB by means of user-defined m-files. Typical small-scale fading channel models are derived such as uncorrelated Rician fading channel and Rayleigh fading channel with Doppler shift. Further, simple and useful MATLAB constructions for approximation of cumulative distribution functions (CDFs) and probability density functions (PDFs) are also given. Finally, a MATLAB based Monte Carlo simulation example is presented, which comprises performance estimation of phase shift keying (PSK) signaling over a Rician fading channel.

- SKLAR, B. Rayleigh fading channels in mobile digital communication systems, Part I: Characterization. IEEE Communications Magazine, 1997, vol. 35, no. 7, p. 90 - 100.
- SUZUKI, H. A statistical model for urban radio propagation. IEEE Transactions on Communications, 1977, vol. COM-25, no. 7, p. 673 to 680.
- PROAKIS, J. G. Digital communications. 2nd ed. New York: McGraw-Hill, 1989.
- CLARKE, R. H. A statistical theory of mobile-radio reception. Bell Systems Technical Journal, 1968, vol. 47, no. 6, p. 957 - 1000.
- JAKES, W. C. Microwave mobile communications. New York: Wiley, 1974.
- PATZOLD, M., KILLAT, U., LAUE, F., LI, Y. On the statistical properties of deterministic simulation models for mobile fading channels. IEEE Transactions on Vehicular Technology, 1998, vol. 47, no. 1, p. 254 - 269.
- HOEHER, P. A statistical discrete-time model for the WSSUS multi-path channel. IEEE Transactions on Vehicular Technology, 1992, vol. 41, no. 4, p. 461 - 468.
- ZHENG, Y., R., XIAO, C. Improved models for the generation of multiple uncorrelated Rayleigh fading waveforms. IEEE Communications Letters, 2002, vol. 6, no. 6, p. 256 - 258.

**T. Fryza, S. Hanus**
[references] [full-text]

Image Compression Algorithms Optimized for MATLAB

This paper describes implementation of the Discrete Cosine Transform (DCT) algorithm to MATLAB. This approach is used in JPEG or MPEG standards for instance. The substance of these specifications is to remove the considerable correlation between adjacent picture elements. The objective of this paper is not to improve the DCT algorithm it self, but to re-write it to the preferable version for MATLAB thus allows the enumeration with insignificant delay. The method proposed in this paper allows image compression calculation almost two hundred times faster compared with the DCT definition.

- WALLACE, G.K. The JPEG Still Picture Compression Standard. Communication of the ACM. 1991, vol. 34, no. 4, p. 30 - 44.
- FRYZA, T. Two Dimensional Discrete Cosine Transform 2D-DCT. PhD course project. Dept. of Radio Electronics, Brno University of Technology (Czech Republic), 2003.
- BLANCHET, G., CHARBIT, M., LIEBENGUTH, D. TP JPEG mo-dule SVA. Travaux Pratiques. Dept. of Signal and Image Processing. Ecole Nationale des Telecommunications, Paris (France), 2000.
- PRADO, J., NICOLAS, J.M. Techniques Numeriques en Traitement de Signal. Elective course papers. Dept. of Signal and Image Processing. Ecole Nationale des Telecommunications, Paris (France), 1999.
- DE VRIES, E. F., KUMARA, G. P. Operations on JPEG Images. Diploma Thesis. Universiteit Leiden, 1994.
- SAAVEDRA, E., GRAUEL, A., MORTON, D. Combined Methods for Image Compression. In Recent Advances in Intelligent Systems and Signal Processing. Kanoni (Greece), 2003, p.233 - 235.
- FRYZA, T. HANUS, S. DCT Velocity Test in Dissimilar Programming Environments. In Conference Proceedings of the 17th International Conference on Applied Electromagnetics and Communica-tions 2003. Dubrovnik (Croatia), 2004, p. 117 - 119.

**H. Ymeri, B. Nauwelaers, K. Maex, D. de Roest**
[references] [full-text]

Modeling the Substrate Skin Effects in Mutual RL Characteristics.,

The goal of this work was to model the influence of the substrate skin effects on the distributed mutual impedance per unit length parameters of multiple coupled on-chip interconnects. The proposed analytic model is based on the frequency-dependent distribution of the current in the silicon substrate and the closed form integration approach. It is shown that the calculated frequency-dependent distributed mutual inductance and the associated mutual resistance are in good agreement with the results obtained from CAD-oriented circuit modeling technique.

- EDELSTEIN, D., SAI-HALASZ, G. A., MII, Y.-J. VLSI On-chip Interconnection Performance Simulations and Measurements. IBM J. Res. Develop., 1995, vol. 39, pp. 383 - 401.
- GROTELUSCHEN, E., DUTTA, L. S., ZAAGE, S. Full-Wave Analysis and Analytic Formulas for the Line Parameters of Transmission Lines on Semiconductor Substrates. Integration, the VLSI J., 1993, vol. 16, pp. 33 - 58.
- RUSSER, P., BIEBL, E., HEINRICH, W. Planar Millimeter Wave Circuits on Silicon. Proceedings of the German IEEE Joint MTT/AP Chapter International Workshop on Silicon-Based High-Frequency Devices and Circuits, Gunzburg, 1994, pp. 1 - 16.
- YMERI, H., NAUWELAERS, B., MAEX, K. Distributed Inductance and Resistance Per-Unit-Length Formulas for VLSI Interconnects on Silicon Substrate. Microwave Opt. Technol. Lett., 2001, vol. 30, pp. 302 - 304.
- CHANG, L., CHENG, K., MATHEWS, T. Simulating Frequency-Dependent Current Distribution for Inductance Modeling of On-Chip Copper Interconnects. Proc. Int. Symp. Physical Design, 2000, pp. 117 - 120.
- WEE, J.-K., PARK, Y.-J., MIN, H.-S., CHO, D.-H., SEUNG, M.-H., PARK, H.-S. Modeling the Substrate Effect in Interconnect Line Characteristics of High-Speed VLSI Circuits. IEEE Trans. Microwave Theory Tech., 1998, vol. 46, pp. 1436-1443.
- YMERI, H., NAUWELAERS, B., MAEX, K., DE ROEST, D., VANDENBERGHE, S. Accurate Analytic Expressions for Frequency-Dependent Inductance and Resistance of Single On-Chip Interconnects on Conductive Silicon Substrate. Physics Letters A, 2002, vol. 293, pp. 195-198.
- ZHENG, J., HAHM, Y.-C., TRIPATHI,V. K., WEISSHAAR, A. CAD-Oriented Equivalent-Circuit Modeling of On-Chip Interconnects on Lossy Silicon Substrate. IEEE Trans. MTT., 2000, vol. 48, pp. 1443-1451.
- HASEGAWA, H., FURUKAWA, M., YANAI, H. Properties of Microstrip Line on Si-SiO2 System. IEEE Trans. Microwave Theory Tech., 1971, vol. 19, pp. 869 - 881.
- KORN, G. A., KORN, T. M. Mathematical Handbook for Scientists and Engineeres. New York: McGraw-Hill, 1951.
- TEGOPOULOS, J. A., KRIEZIS, E. E. Eddy Currents in Linear Conducting Media. Amsterdam: Elsevier, 1985.
- YMERI, H., NAUWELAERS, B., MAEX, K., DE ROEST, D., VANDENBERGHE, S. Frequency-Dependent Expressions of Inductance and Resistance of Microstrip Line on Silicon Substrate. Microwave Opt. Technol. Letters, 2002, vol. 33, pp. 349 - 352.
- EO, Y., EISENSTADT, W. High Speed VLSI Interconnection Lines and Packages in High Speed Integrated Circuits. IEEE Trans. Comp., Packag., Manufact. Technol. B, 1993, vol. 16, pp. 552 - 562.
- YMERI, H., NAUWELAERS, B., MAEX, K., DE ROEST, D. New Modeling Approach of On-Chip Interconnects for RF Integrated Circuits in CMOS Technology. Microelectronics International, 2003 vol. 20, pp. 41 - 44.
- ABRAMOWITZ, M., STEGUN, I. A. Handbook of Mathematical Functions, New York: Dover, 1965.

**D.Orel, J. Rozman**
[references] [full-text]

A Computer Simulation of Ultrasound Thermal Bio-Effect in Embryonic
Model

At the present time, the usage of ultrasound diagnostic equipment has become an inseparable part of diagnosis for a number of medical investigations. Several scientific studies published in the last years showed that when applying a diagnostic ultrasound system on animals it is possible to create negative changes in tissues. New ultrasound technologies and higher output acoustic powers have brought a possible risk connected to the usage of ultrasound in diagnostics. The knowledge of risk level and exploration of limiting factors is an important point for the assessment of marginal ultrasound exposure values of medical investigation during pregnancy, especially in the first trimester. The contribution presents a MATLABZ application for modeling of tissue heating in human embryos at the developmental age of seven and eight weeks. Recent calculations of US fields, which are generated by several types of various unfocused single transducers (rectangular, circular, and annular), represent maximum temperature elevation of 0.4 °C in embryonic model tissues for the exposure of 1 min. The models of embryonic tissue heating provide comparative studies of possible bio-effect with the purpose to explore limiting factors of ultrasound exposure.

- BARR, L., L. Clinical Concerns in the Ultrasound Exposure of the Developing Central Nervous System. Ultrasound in Med.& Biol., 2001, vol. 27, p. 889 - 892.
- BARNETT, S., B. Intracranial Temperature Elevation from Diagnostic Ultrasound. Ultrasound in Med.& Biol., 2001, vol. 27, p. 883 - 888.
- HILL, C., R. Physical Principles of Medical Ultrasonics. 1st ed., Chichester, England: Ellis Horwood Limited, 1986.
- MALINSKY, J., LICHNOVSKY, V. Prehled Embryologie cloveka v obrazech. 2nd ed., Olomouc: Univerzita Palackeho, 2001.
- NYBORG, W. L. Biological Effects of Ultrasound: Development of Safety Guidelines. Part II: General Review. Ultrasound in Med.& Biol., 2001, vol. 27, p. 301 - 333.
- OHTSUKI, S. Sound Field of Disc and Concave Circular Transducers. In Proceeding of the Sendai Symposium on Ultrasonic Tissue Characterisation 1994, Sendai 1994, pp. 53 - 62.
- OREL, D., ROZMAN, J. Modelovani ultrazvukovych poli idealnich menicu. Lekar a technika, 2002, vol. 33, no. 1, p. 13 - 16.
- OREL, D., ROZMAN, J. The Modelling of Tissue Heating Caused by Applied Diagnostic Ultrasound. In Conference Proceeding of the 16th International EURASIP Conference BIOSIGNAL. Brno, 2002, p. 430 -432.
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- SHAW, A. et al. Assessment of the Likely Thermal Index Values for Pulsed Ultrasonic Equipment - Stage 1: calculation based on manufacture's data. Report CIRA (EXT)018. Teddington, UK: National Physical Laboratory, 1997.
- WHITTINGHAN, T., A. Estimated Fetal Cerebral Ultrasound Exposures from Clinical Examinations. Ultrasound in Med.& Biol., 2001, vol. 27, p. 877 - 882.
- British Medical Ultrasound Society: Guidelines for the safe use of diagnostic ultrasound equipment. http://www.bmus.org/BMUS Safety Guidelines final.htm, August 2003.
- European Federation of Societies for Ultrasound in Medicine and Biology: Clinical Safety Statement for Diagnostic Ultrasound. http://www.efsumb.org/statemflo.htm, August 2003.

**T. Kratochvil**
[references] [full-text]

Utilization of MATLAB for Digital Image Transmission Simulation.,

The paper deals with the utilization of Matlab for simulation and analysis of the digital image transmission and transmission distortions in DTV (Digital Television) and DVB (Digital Video Broadcasting) area. The simulation model that covers selected phenomena of DVB standard baseband signal processing applied in Matlab is presented and features of the protection against transmission errors are outlined. The practical results of FEC (Forward Error Correction) codes efficiency are presented and at the end the GUI application for experimental simulation and education is outlined with a simulation example.

- RIEMERS, U. Digital Video Broadcasting. New York, Berlin Heildeberger:Springer - Verlag, 2001.
- COLLINS, G. W. Fundamentals of Digital Television Transmission.A Wiley-Interscience Publication. New York: John Wiley & Sons,Inc., 2001.
- JAN, J. Digital filtering, analysis and restoration of signals. Brno:Brno University of Technology, 1997 (in Czech).
- KRATOCHVIL, T. Simulation and analysis of the digital televisionsignal transmission. In Eurocon 2003 Computer as a Tool ProceedingsVolume I. Ljubljana (Slovenia), 2003, p. 459 - 463.
- HRDINA, J. Simulation of the digital signal transmission in TV technique.Diploma thesis. Brno: Brno University of Technology, 2003(in Czech).
- KRATOCHVIL, T. Simulation of the Digital Real TransmissionChannel Characteristics. Research report of the grant project of theCzech Ministry of Education no. 156/2001. Brno: Brno University ofTechnology, 2001 (in Czech).
- KRATOCHVIL, T., HRDINA, J. Utilization of Matlab for educationof the digital image transmission. In Proceedings of the 10th ConferenceMatlab 2002. Prague: Humusoft, 2002, p. 261 - 264.

**M. Karafiat, F. Grezl**
[references] [full-text]

Using MATLAB for Analysis of TRAP System

This article describes a Matlab function for reading and processing file outputs from a structure of classifiers. These classifiers - neural nets - are used in speech recognition based on temporal trajectories (TRAP) of energy in frequency bands. This nonstandard approach is introduced and the program is presented. The utility of resulting figures is enhanced by the possibility of reading and displaying results from all critical bands at once. Resulting analyses are more focused on the reliability of classifiers than on the basic accuracy measure. The first uses colors and their depth to display both cues, reliability and accuracy, in one informative picture. Others are focused on more precise measures, where it is possible to precisely define classifier mistakes.

- ADAMI, A., BURGET, L., DUPONT, S., GARUDADRI, H., GRE-ZL, F., HERMANSKY, H., JAIN, P., KARAJEKAR, S., MORGAN, N., SIVADAS, S., Qualcomm-ICSI-OGI features for ASR. In Pro-ceedings of International Conference on Spoken Language Proces-sing, ICSLP 2002, Denver, Colorado, USA, 2002.
- GREZL, F., HERMANSKY, H., Local averaging and differentiating of spectral plane for trap-based ASR. In Proceedings of Eurospeech 2003, Geneva, Switzerland, 2003.
- KINGSBURY, B., JAIN, P., ADAMI, A., A hybrid HMM/TRAPS model for robust voice activity detection. In Proceedings of International Conference on Spoken Language Processing, ICSLP 2002, Denver, Colorado, USA, 2002.
- CERNOCKY, J., MATEJKA, P., SCHWARZ, P., Recognition of phoneme strings using trap technique. In Proceedings of Eurospeech 2003, Geneva, Switzerland, 2003.
- CERNOCKY, J., Temporal processing for feature extraction in speech recognition. Habilitation thesis. Brno: Brno Univ. of Technology, 2002. http://www.fit.vutbr.cz/~cernocky/publi/2002/habil.pdf
- HERMANSKY, H., SHARMA, S., TRAPS - classifiers of temporal patterns. In Proceedings of 5th International Conference on Spoken Language Processing, ICSLP 98, Sydney, Australia. Paper 615.
- JOHNSON, D., ftp://ftp.icsi.berkeley.edu/pub/real/davidj/quicknet-v0 96.tar.gz.
- The MathWorks, Inc., Using MATLAB, Natick, MA, 1997.

**S. Zvanovec, P. Pechac, M. Klepal**
[references] [full-text]

Wireless LAN Network Design: Site Survey or Propagation Modeling?

There are two basic ways to deploy wireless LAN access points in an indoor scenario: manual deployment using a site survey based on empirical measurements or planning using a software tool with built-in signal propagation models. In this paper advantages and disadvantages of both ways are discussed. The planning based on propagation modeling is recognized as a highly preferable approach for design of large WLANs. Experimental data in this paper were processed in MATLAB.

- OHRTMAN, F., ROEDER, K. Wi-Fi Handbook: Building 802.11bWireless Networks. McGraw-Hill, 2003.
- IEEE 802.11 Working Group,http://grouper.ieee.org/groups/802/11/index.html
- ITU-T Recommendation E.800: Terms and definitions related toquality of service and network performance including dependability.
- Symbol Technologies, http://www.symbol.com.
- SILER, M., WALRAND, J. Monitoring Quality of Service:Measurement and Estimation. Proceedings of the 37th IEEEConference on Decision and Control, vol. 1, 1998.
- The Internet Engineering Task Force (IETF),http://www.ietf.org/html.charters/ippm-charter.html.
- Quality of future Internet Services: COST263,http://www.fokus.fraunhofer.de/research/cc/glone/projects/cost263/.
- Orinoco WLAN Card Specifications, http://www.lucent.com/orinoco
- ZVANOVEC, S., VALEK, M., PECHAC, P. Results of IndoorPropagation Measurement Campaign for WLAN Systems Operatingin 2.4 GHz ISM Band. The International Conference on Antennasand Propagation ICAP 2003, Exeter, UK, p.63-66.
- YOUSSEF, M., AGRAWALA, A. Small-scale Compensation forWLAN Location Determination Systems. Wireless Communicationsand Networking, IEEE WCNC 2003, vol. 3, 2003.
- CATEDRA, M., PEREZ-ARRIAGA, J. Cell Planning for WirelessCommunications. Artech House,1999.
- KLEPAL, M. , PECHAC, P. Prediction of Wide-Band Parameters ofMobile Propagation Channel. XXVIIth URSI General Assembly theInternational Union of Radio Science [CD-ROM], Maastricht, 2002,pp. 459.
- Digital Mobile Radio towards Future Generation Systems, COST231 Final Report, Brussels, 1996.
- PECHAC, P., KLEPAL, M., ZVANOVEC, S. Results of IndoorPropagation Measurement Campaign at 1900 MHz.Radioengineering, 2001,vol. 10, p. 2-4.
- ZVANOVEC, S. Coverage Prediction for GSM Picocells. DiplomaThesis, CTU Prague, 2002 (in Czech).
- TAMMINEM, J. 2.4 GHz WLAN Radio Interface -Presentation atTampere University of Technology 2002, www.radionet.fi.
- CHEUNG, D., PRETTIE, C. A Path Loss Comparison Between the 5GHz UNII Band (802.11a) and the 2.4 GHz ISM Band (802.11b).Intel Labs Comporation, 2002.
- TAROKH, V., GHASSEMZADEH, S.S. 2002: The Ultra-widebandIndoor Path Loss Model. IEEE P802.15-02/277-SG3a and IEEEP802.15-02/278-SG3a.
- PECHAC, P., KLEPAL, M. Empirical Models for Indor Propagationin CTU Prague Buildings. Radioengineering, 2000, vol. 9, no. 1, p.31-36.
- European Radiocommunications Committee, Compatibility StudiesRelated to the Possible Extensions Band For HIPERLAN at 5 GHz,Draft, SE24H(99)3 rev1, 1999.
- ANDERSON, CH. R. Design and Implementation of anUltrabroadband Millimetre-Wavelength Vector Sliding CorrelatorChannel Sounder and In-Building Multipath Measurements at 2.5 &60 GHz. Diploma thesis, Virginia Polytechnic Institute, 2002.
- Architect/One automated planning tool, www.strixsystems.com.

**M. Grabner, V. Kvicera**
[references] [full-text]

Clear-Air Propagation Modeling using Parabolic Equation Method

Propagation of radio waves under clear-air conditions is affected by the distribution of atmospheric refractivity between the transmitter and the receiver. The measurement of refractivity was carried out on the TV Tower Prague to access evolution of a refractivity profile. In this paper, the parabolic equation method is used in modeling propagation of microwaves when using the measured data. This paper briefly describes the method and shows some practical results of simulation of microwave propagation using real vertical profiles of atmospheric refractivity.

- GRABNER, M., KVICERA, V. Refractive Index Measurement at TV Tower Prague. Radioengineering, 2003, vol. 12, no. 1, p. 5 - 7.
- DOCKERY, G. D. Modeling Electromagnetic Wave Propagation in the Troposphere using the Parabolic Equation. IEEE Transaction on Antennas and Propagation, 1988, vol. 3, no. 10, p. 1464 - 1470.
- BARRIOS, A. E. A Terrain Parabolic Equation Model for Propaga-tion in the Troposphere. IEEE Transaction on Antennas and Propagation, 1994, vol. 42, no. 1, p. 90 - 98.
- KUTTLER, J. R., DOCKERY G. D. Theoretical Description of the Parabolic Approximation/Fourier Split Step Method of Representing Electromagnetic Propagation in the Troposphere. Radio Science, 1991, vol. 26, no. 2, p. 381 - 393.
- SOKOL, Z., STEKL, J. 3-D Mesoscale Objective Analysis of Selected Elements from SYNOP and SYRED Reports. Meteorol. Z., 1994, N.F.3, H.4, p. 242-246.
- REZACOVA, D., FISER, O., RAMON SAEZ, L. Statistics of the Radio Refractivity Derived from Radiosounding Data. Radioengineering, 2003, vol. 12, no. 4, pp. 84-88.

**S. Vitek, J. Hozman**
[references] [full-text]

Modeling of Imaging Systems in MATLAB

For many applications in image processing it is necessary to know model of imaging system, which has been used for image data obtain. Knowledge about system can be used for the simulation of an image data in astronomy (telescope and CCD camera, for example in near IR band) or we can treat the compression algorithm as any other imaging system and perform objective image quality measurement.

- HOLST, G.C. CCD arrays, Cameras and Displays. 2nd ed. Bellingham: SPIE Press, 1998.
- YALID-PECHT Geometrical MTF for Different Pixel Active Area Shapes. Optical Engineering, 2000, 34, p. 859 - 865.
- VITEK, S., HOZMAN J. Image Quality Influenced by Selected Image Sensor Parameters. In Photonics Prague. Prague, 2002, p. 167

**H. Kuchynkova**
[references] [full-text]

Compatibility of Data Transfer between CAD Applications

Compatibility of data transfers between individual CAD programs is topical when in another program we need to use a drawing or a 3D model created in a program that uses a different modeling kernel. The paper characterizes features and structures of existing CAD formats, problems in their transfer, it notes the export/import conversion through the IGES, SAT, STEP and STL formats. It takes a closer look at using the STL format for visualization and animation.

- TOMIS, M. Datove prenosy mezi CAD/CAM aplikacemi. itCAD Journal, 2001, vol. 10. no.3, p.3-5.
- STEINBERG, B., RZDAN, A., FARIN, G. Reverse Engineering Trimmed NURBS Surfaces from Laser Scanned Data. Available from http://link.springer.de/link/service/journals/00170/papers/ /0016011/00160784.pdf
- BECKA,J. Pouziti STEP pro vymenu formatu CAD. Available from http://www.czstep.cz/step/aktivity/cvut_99.html
- NEMEC, L. Konverze formatu. http://forum.3dscena.cz/
- CEVELA L. Vymena dat mezi ruznymi systemy CAD. [HTML document], http://www.automa.cz/automa/2001/

**E. Cocherova**
[references] [full-text]

Modification of Ordinary Differential Equations MATLAB Solver

Various linear or nonlinear electronic circuits can be described by the set of ordinary differential equations (ODEs). The ordinary differential equations can be solved in the MATLAB environment in analytical (symbolic toolbox) or numerical way. The set of nonlinear ODEs with high complexity can be usually solved only by use of numerical integrator (solver). The modification of ode23 MATLAB numerical solver has been suggested in this article for the application in solution of some special cases of ODEs. The main feature of this modification is that the solution is found at every prescribed point, in which the special behavior of system is anticipated. The extrapolation of solution is not allowed in those points.

- PRESS, W. H., FLANNERY, B. P., TEUKOLSKY, S. A., VETTERLING,W. T. Numerical recipes in C. Cambridge: Cambridge UniversityPress, 1992.
- SHAMPINE, L. F., REICHELT, M. W. The MATLAB ODE suite.SIAM Journal on Scientific Computing. 1997, vol. 18, no. 1, p. 1-22.
- http://kre.elf.stuba.sk/~cocherova.
- COCHEROVA, E. Refractory period determination in the Hodgkin -Huxley model of the nerve fibre membrane. In Proceedings of the 4thElectronic Circuits and System Conference. Bratislava, 2003, p. 171to 174.

**Z. Raida et al.**
[references] [full-text]

Electronic Textbook of Electromagnetic Waves

Teaching university courses, which deal with the phenomena of the electromagnetic (EM) substantiality and their applications, is rather difficult due to their abstract nature. Therefore, teaching has to be accompanied by clear explanations and by simulations illustrating the examined topics. This is why an electronic textbook (ET) of EM waves and applications was developed. The ET presents theoretical descriptions of selected EM phenomena on two levels - on a bachelor's one and a master's one. Descriptive parts of the ET are completed by computer programs, which enable the reader to simulate the studied phenomena. Moreover, the ET explains the practical implementation of simulation routines in MATLAB, which helps students to understand a relationship between rather complicated mathematics and a relatively simple source code of its software implementation. Since the ET is freely accessible on the web, students can use it whenever as a classical textbook, a handbook or a software package. This fact positively influences the students' knowledge and understanding as proven by our experience.

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Statistics of Radio Refractivity Derived from Prague Radiosounding Data

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