1998/4

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Recent Submissions

Now showing 1 - 5 of 9
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    An Approach to 2D Wavelet Transform and Its Use for Image Compression
    (Společnost pro radioelektronické inženýrství, 1998-12) Vargic, R.
    In this paper is constructed a new type of two-dimensional wavelet transform. Construction is based on lifting scheme. We transform 1D wavelets with symmetrical factorisation to their 2D counterparts. Comparison to existing similar 2D wavelet constructions is given. Application for image compression is given using progressive (SP1HT) and classical type transform coder.
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    ARC Filters with Diamond Transistors and Buffers
    (Společnost pro radioelektronické inženýrství, 1998-12) Dostal, T.
    Active RC first and second order filters using diamond transistors (voltage controlled current sources) and voltage diamond buffers (voltage controlled voltage sources) are given in this paper. Circuits are simulated and experimentally compared.
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    Differential GMSK Receivers with Phase Control for Narrowband Radio Communications
    (Společnost pro radioelektronické inženýrství, 1998-12) Mahdavi, A.; Gordon, D.; Riley, N.
    An implementation method for differential Gaussian Minimum Shift Keying receivers with Phase Control is presented. It is shown that in such receivers the effect' of InterSymbol Interference (ISI) on the signal, caused by the adjacent bits is reduced by introducing Phase Control in accordance with the data stream. This results in improved system performance, particularly at low values of time-bandwidth product of the premodulation gaussian filter where ISI is high. With the application of this technique the performance of differential receiver is enhanced to a level where it is comparable to that of coherent receiver and yet avoids the problems associated with the complex carrier recovery in the latter case.
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    Rain Scattering and Co-ordinate Distance Calculation
    (Společnost pro radioelektronické inženýrství, 1998-12) Hajny, M.
    Calculations of scattered field on the rain objects are based on using of Multiple MultiPole (MMP) numerical method. Both bi-static scattering function and bi-static scattering cross section are calculated in the plane parallel to Earth surface. The co-ordination area was determined using the simple model of scattering volume [1]. Calculation for frequency 9.595 GHz and antenna elevation of 25° was done. Obtained results are compared with calculation in accordance to ITU-R recommendation.
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    Speech Segmentation Using Bayesian Autoregressive Changepoint Detector
    (Společnost pro radioelektronické inženýrství, 1998-12) Cmejla, R.; Sovka, Pavel
    This submission is devoted to the study of the Bayesian autoregressive changepoint detector (BCD) and its use for speech segmentation. Results of the detector application to autoregressive signals as well as to real speech are given. BCD basic properties are described and discussed. The novel two-step algorithm consisting of cepstral analysis and BCD for automatic speech segmentation is suggested.