December 1998, Volume 7, Number 4

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R. Vargic [full-text]
An Approach to 2D Wavelet Transform and Its Use for Image Compression

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.

S. Pagel, F. P. Fontan, M. Van Looy [full-text]
A PC Controlled Filter

In this paper we present a switched capacitor filter design using the SC22324 1C, which is fitted with an E2PROM. It contains four digitally programmable switched-capacitor filter sections, in order to obtain different responses. The SC22324 also contains the on-chip RAM. We'd like to explain, how could the on-chip RAM controlled via a PC. In this way the chip may be used afterwards with a menu where the user may select the wanted parameters.

R. Cmejla, P. Sovka [full-text]
Speech Segmentation Using Bayesian Autoregressive Changepoint Detector

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.

A. Mahdavi, D. Gordon, N. Riley [full-text]
Differential GMSK Receivers with Phase Control for Narrowband Radio Communications

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.

J. Rozman, M. Zona, J. Peroutik [full-text]
An Ischemic Disease Classification of Lower Limbs

An ischemic disease of lower limbs is a manifestation of general arteriosclerosis. Its early noninvasive diagnostic is possible using the approach of the Doppler measurement of the blood flow in the vessels with following classification by a neural network expert system.

M. Hajny [full-text]
Rain Scattering and Co-ordinate Distance Calculation

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.

A. Prokes [full-text]
Generalized Sampling Theorem for Bandpass Signals

Bandpass time-continuos signals are shown being able to be uniquely expressed in terms of the samples gi(nTv) of the impulse responses gi(t) of m linear time-invariant systems with input f(t) sampled at 1/m Nyquist rate. Various known extensions of the sampling theorem can be regarded as special cases of the resulting generalized sampling expansion of f(t).

T. Dostal [full-text]
ARC Filters with Diamond Transistors and Buffers

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.

E. Machuca, P. Sovka, V. Davidek [full-text]
Study of 2-input 2-output Blind Signal Separation by Output Decorrelation

The simulations and experiments representing the initial study of the output decorrelation approach to blind signal separation are presented in this paper. The definition of performance indexes for the evaluation and comparison of different algorithms are proposed. Two algorithms are compared. Some first results of real experiments are discussed.

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