2011/3
Browse
Recent Submissions
- ItemLocation Privacy on DVB-RCS using a “Spatial-Timing” Approach(Společnost pro radioelektronické inženýrství, 2011-09) Aggelis, Aggelis; Sarris, Emmanuel T.DVB-RCS synchronization scheme on the Return Channel requires the RCSTs to be programmed with their location coordinates with an accuracy of no more than a few kilometers. RCSTs use this location information in their ranging calculation to the servicing satellite. For certain users this location information disclosure to the network operator can be seen as a serious security event. Recent work of the authors overcame this requirement by cloaking the location of an RCST in such a way (based on "spatial/geometric" symmetries of the network) that the respective ranging calculations are not affected. In this work we argue that timing tolerances in the Return Channel synchronization scheme, accepted by the DVB-RCS standard, can be used in combination to the "spatial" method, further enhancing the location privacy of an RCST. Theoretical findings of the proposed "spatial-timing" approach were used to develop a practical method that can be used by workers in the field. Finally this practical method was successfully tested on a real DVB-RCS system.
- ItemCFOA-Based Lossless and Lossy Inductance Simulators(Společnost pro radioelektronické inženýrství, 2011-09) Kacar, Firat; Kuntman, HakanInductance simulator is a useful component in the circuit synthesis theory especially for analog signal processing applications such as filter, chaotic oscillator design, analog phase shifters and cancellation of parasitic element. In this study, new four inductance simulator topologies employing a single current feedback operational amplifier are presented. The presented topologies require few passive components. The first topology is intended for negative inductance simulation, the second topology is for lossy series inductance, the third one is for lossy parallel inductance and the fourth topology is for negative parallel (-R) (-L) (-C) simulation. The performance of the proposed CFOA based inductance simulators is demonstrated on both a second-order low-pass filter and inductance cancellation circuit. PSPICE simulations are given to verify the theoretical analysis.
- ItemSingle-Input Five-Output Electronically Tunable Current-Mode Biquad Consisting of Only ZC-CFTAs and Grounded Capacitors(Společnost pro radioelektronické inženýrství, 2011-09) Satansup, Jetsdaporn; Tangsrirat, WorapongThis paper presents an electronically tunable current-mode biquadratic filter constructing with four Z-copy current follower transconductance amplifiers (ZC-CFTAs) and only two grounded capacitors. The presented filter can realize all the five standard biquadratic functions simultaneously without requiring any component matching conditions and connecting any relevant output currents. The circuit has one low-impedance input and five high-impedance outputs, resulting in easy cascadability in current-mode. Also, the developed circuit exhibits the advantage of non-interactive electronic control of the natural angular frequency and the quality factor Q along with low incremental active and passive sensitivities. Computer simulation results using PSPICE program are given to confirm the validity of the theoretical prediction and to point out the attractive performance of the circuit.
- ItemSupplementary Inductance Simulator Topologies Employing Single DXCCII(Společnost pro radioelektronické inženýrství, 2011-09) Metin, BilginIn this study, six grounded inductance simulator circuits are presented including additional useful features in comparison to previous dual-X current conveyor (DXCCII) based implementations. To demonstrate the performance and usefulness of the presented circuits, one of them is used to construct a fifth order Butterworth high-pass filter and a current-mode multifunction filter as application examples. Simulation results are given to confirm the theoretical analysis. The derived DXCCII and its applications are simulated using CMOS 0.35 μm technology.
- ItemExploiting Temporal Context in High-Resolution Movement-Related EEG Classification(Společnost pro radioelektronické inženýrství, 2011-09) Dolezal, Jaromir; Stastny, Jakub; Sovka, PavelThe contribution presents an application of a movement-related EEG temporal development classification which improves the classification score of voluntary movements controlled by closely localized regions of the brain. A dynamic Hidden Markov Model-based (HMM) classifier specifically designed to capture EEG temporal behavior was used. Surprisingly, HMM classifiers are rarely used for BCI design despite of their advantages. Because of this we also experimented with Learning Vector Quantization, Perceptron, and Support Vector Machine classifiers using a feature space which captures the temporal dynamics of the data. The results presented in this work show that HMM achieves the best performance due to an a priori information on physiological behavior of EEG inserted to the HMM classifier. Feature extraction process and problems with classification were analyzed as well. Classification scores of 66.7% – 94.7% were achieved in our experiments.