2007/3
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Recent Submissions
- ItemSpreading Sequences Generated Using Asymmetrical Integer-Number Maps(Společnost pro radioelektronické inženýrství, 2007-09) Sebesta, VladimirChaotic sequences produced by piecewise linear maps can be transformed to binary sequences. The binary sequences are optimal for the asynchronous DS/CDMA systems in case of certain shapes of the maps. This paper is devoted to the one-to-one integer-number maps derived from the suitable asymmetrical piecewise linear maps. Such maps give periodic integer-number sequences, which can be transformed to the binary sequences. The binary sequences produced via proposed modified integer-number maps are perfectly balanced and embody good autocorrelation and crosscorrelation properties. The number of different binary sequences is sizable. The sequences are suitable as spreading sequences in DS/CDMA systems.
- ItemBiquads Based on Single Negative Impedance Converter Implemented by Classical Current Conveyor(Společnost pro radioelektronické inženýrství, 2007-09) Dostal, Tomas; Axman, VladimirThe paper deals with continuous-time ARC biquadratic (second-order) filters based on the single classical three-port current conveyors, so called second generation CC II. A unique application of the CC II is discussed, when the terminals Y and Z are connected together. Using this way a negative impedance converter is obtained as a suitable building block in synthesis of several biquads, including notch filters.
- ItemSoftware for CATV Design and Frequency Plan Optimization(Společnost pro radioelektronické inženýrství, 2007-09) Hala, OndrejThe paper deals with the structure of a software medium used for design and sub-optimization of frequency plan in CATV networks, their description and design method. The software performance is described and a simple design example of energy balance of a simplified CATV network is given. The software was created in programming environment called Delphi and local optimization was made in Matlab.
- ItemAnalysis of Analog Neural Network Model with CMOS Multipliers(Společnost pro radioelektronické inženýrství, 2007-09) Docheva, Liliana; Bekiarski, Alexander; Dochev, IvoThe analog neural networks have some very useful advantages in comparison with digital neural network, but recent implementation of discrete elements gives not the possibility for realizing completely these advantages. The reason of this is the great variations of discrete semiconductors characteristics. The VLSI implementation of neural network algorithm is a new direction of analog neural network developments and applications. Analog design can be very difficult because of need to compensate the variations in manufacturing, in temperature, etc. It is necessary to study the characteristics and effectiveness of this implementation. In this article the parameter variation influence over analog neural network behavior has been investigated.
- ItemIterative Unsupervised GMM Training for Speaker Indexing(Společnost pro radioelektronické inženýrství, 2007-09) Paralic, Martin; Jarina, RomanThe paper addresses a novel algorithm for speaker searching and indexation based on unsupervised GMM training. The proposed method doesn\'t require a predefined set of generic background models, and the GMM speaker models are trained only from test samples. The constrain of the method is that the number of the speakers has to be known in advance. The results of initial experiments show that the proposed training method enables to create precise GMM speaker models from only a small amount of training data.