2006/2

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Now showing 1 - 5 of 9
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    Difference Equations with Forward and Backward Differences and Their Usage in Digital Signal Processor Algorithms
    (Společnost pro radioelektronické inženýrství, 2006-06) Smekal, Zdenek
    In the paper the relation is given between linear difference equations with constant coefficients those obtained via the application of forward and backward differences. Relation is also established between input-output difference equations and state-space difference equations, which define the state of inner quantities of a discrete system. In conclusion, the state-space representation of a discrete system is given, which is suitable for implementing a discrete system in the microprocessor and digital signal processor. The resultant solution consists of the response to input signal and the response to non-zero initial conditions.
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    3D Motion Estimation of Human Head by Using Optical Flow
    (Společnost pro radioelektronické inženýrství, 2006-06) Mihalik, Jan; Michalcin, Viktor
    The paper deals with the new algorithm of estimation of large 3D motion of the human head by using the optical flow and the model Candide. In the algorithm prediction of 3D motion parameters in a feedback loop and with multiple iterations was applied. The prediction of 3D motion parameters does not require creating of the synthesized frames but directly uses the frames of input videosequence. Next the algorithm does not need extracting of feature points inside the frames because they are given by the vertices of the used calibrated model Candide. As achieved experimental results show, the iteration process in prediction of 3D motion parameters increased the accuracy of estimation above all the large 3D motion. Such a way the estimation error is decreased without its accumulation in long videosequence. Finally the experimental results show that for 3 iterations a state of saturation was achieved what means that by next increasing of the number of iterations practically no significant increasing of the accuracy of estimation of 3D motion parameters is occurred.
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    L-System Tool for Generating Fractal Antenna Structures with Ability to Export into EM Simulators
    (Společnost pro radioelektronické inženýrství, 2006-06) Hazdra, Pavel; Mazanek, Milos
    An L-System (Lindenmayer system) is a scheme primarily developed in the area of the computer science for simulating the development of biological structures. It has also been found very useful for generating the geometry of various fractal antennas. A Matlab environment has been used for both implementing an in-plane L-systems algorithm and for creating appropriate files for widely used EM simulators like the IE3D and the CST Microwave Studio. Finally, the performance of the developed script is demonstrated on two fractal microstrip patch antennas.
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    Quad-Band U-Slot Antenna for Mobile Applications
    (Společnost pro radioelektronické inženýrství, 2006-06) Palmero, Eduardo de las Heras; Raida, Zbynek; Ruiz, Roberto Lamadrid
    In this paper, two different planar quad-band antennas are designed, modeled, fabricated and measured. Subsequently, the antennas are redesigned using an electromagnetic band gap substrate (EBG). Those new planar antennas operate in four frequency bands: 900 MHz, 1 800 MHz (both GSM), 1 900 MHz (USA) and 2 400 to 2 500 MHz (Bluetooth) The antenna has four narrow U-shaped slots etched to the patch. Using software, CST Microwave Studio [1], Zeland IE3D [2], and FEMLAB [3], simulations have been carried out to investigate the antenna\'s performance and characteristics. The antennas designed have been also built and measured to compare the real results with those obtained from the simulations.
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    Statistical CAC Methods in ATM
    (Společnost pro radioelektronické inženýrství, 2006-06) Baronak, Ivan; Kvackaj, Peter
    Admission control is a very useful tool for a network operator. It enables effective link utilization with QoS guaranty. Without doubts, CAC function will be important part in evolution of next generation networks. The question, how to choose suitable CAC method as admission control, is crucial for effective exploitation of CAC function. In this paper, we compare three statistical CAC methods providing their suitability as control for specific traffic: Method of Effective Bandwidth, Diffusion Approximation Method and Gaussian Approximation Method.