2008/4

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Parametric Study of Mushroom-like and Planar Periodic Structures in Terms of Simultaneous AMC and EBG Properties
(Společnost pro radioelektronické inženýrství, 2008-12) Kovacs, Peter; Raida, Zbynek; Martinez-Vazquez, Marta
In the paper, the parametric analysis of a mushroom-like and a planar metallo-dielectric periodic structure with square unit cell and metallic patch is presented. First, the angular stability for different unit cell settings was studied. Second, restrictions for simultaneous behavior as artificial magnetic conductor (AMC) and electromagnetic band gap (EBG) are briefly discussed. Finally, main differences between the mushroom-like and the planar structure are specified and conclusions are formulated.
The Time Difference of Arrival Estimation of Wi-Fi Signals
(Společnost pro radioelektronické inženýrství, 2008-12) Nemec, Zdenek; Bezousek, Pavel
The papers deals with a modeling of a Time- Difference of Arrival system for a subscriber station localization, based on the 802.11 standard wireless network. In the case of severe multipath effects the standard TDOA estimation methods, based on correlation of signals, received by conveniently displaced receiving stations show large errors. Thus, a new algorithm is proposed using received signals decomposition to a set of delayed replicas. This represents a linear estimation of reflected signals amplitudes. The described method leads to a better estimation of time differences of the signals, propagating on the direct paths between the emitter and the receiving stations.
A New CAC Method Using Queuing Theory
(Společnost pro radioelektronické inženýrství, 2008-12) Baronak, Ivan; Kvackaj, Peter
The CAC (Connection Admission Control) method plays an important role in the ATM (Asynchronous Transfer Mode) network environment. The CAC is the first step in the prevention of congested states in the network topology, and conducts to the optimal network resources utilization. The paper is aimed to propose an enhancement for a convolution method that is one of the statistical CAC methods used in ATM. The convolution method uses a buffer-less assumption in the estimation of the cell loss. Using formulas for the G/M/1 queuing system, the cell loss can be estimated as the buffer overflow probability. In this paper, the proposed CAC method is compared with other three statistical CAC methods, and conclusions regarding the exploitation of the CAC method are presented
Design of Microstrip Band Pass Fractal Filter for Suppression of Spurious Band
(Společnost pro radioelektronické inženýrství, 2008-12) Baral, R. N.; Singhal, P. K.
In this paper, the design and subsequent fabrication of a hairpin-line band pass filter has been proposed. This filter exhibits periodic frequency response. By proper design, the spurious bands are being suppressed significantly through the implementation of Koch fractal on the microstrip coupled line.
Implementation and Evaluation of Power Consumption of an Iris Pre-processing Algorithm on Modern FPGA
(Společnost pro radioelektronické inženýrství, 2008-12) Blasinsky, Henryk; Amiel, Frederic; Ea, Thomas; Rossant, Florence; Mikovicova, Beata
In this article, the efficiency and applicability of several power reduction techniques applied on a modern 65nm FPGA is described. For image erosion and dilation algorithms, two major solutions were tested and compared with respect to power and energy consumption. Firstly the algorithm was run on a general purpose processor (gpp) NIOS and then hardware architecture of an Intellectual Property (IP) was designed. Furthermore IPs design was improved by applying a number of power optimization techniques. They involved RTL level clock gating, power driven synthesis with fitting and appropriate coding style. Results show that hardware implementation is much more energy efficient than a general purpose processor and power optimization schemes can reduce the overall power consumption on an FPGA.

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