2005/1

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    Analysis of Rain Rate Spatial Cross-Correlation Coefficients in the Basque Country Area
    (Společnost pro radioelektronické inženýrství, 2005-04) Antonio Romo, Juan; Anitzine, Ignacio F.; Fontan, Fernando P.; Marino, Perfecto
    This paper reports on a study on the spatial characteristics of rain rates recorded in the Basque region in northern Spain. To perform this study a network of eighty raingauges spread throughout the region has been used. Statistical parameters such as the spatial cross-correlation coefficient and the space-time cross-correlation coefficient were calculated and their evolution with separation distance studied. It is hoped that information reported could be useful in better understanding characteristics of rain and in developing countermeasures for terrestrial and satellite radio networks operating at frequencies above 10 GHz.
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    Estimation of Spread Spectrum Signal Parameters Utilizing Wavelet Transform Analysis
    (Společnost pro radioelektronické inženýrství, 2005-04) Leonis, Nikolaos; Katsoulis, George; Amditis, Angelos; Uzunoglu, Nikolaos
    This paper investigates the application of wavelet transform (WT) to the extraction of particular features of direct sequence spread spectrum signals. The WT is exploited to the point that not only its capabilities but also its limitations are exposed to achieve the specific task of identifying spread spectrum signal parameters. The capabilities focus on the detection of the chipping sequence, while the limitations refer primarily to the advent of direct sequence CDMA signals. In the latter case no progress has yet been made to distinguish the different chipping sequences by the WT, whose resultant effect on the carrier appears as a single-phase change.
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    Detection of Acoustic Change-Points in Audio Streams and Signal Segmentation
    (Společnost pro radioelektronické inženýrství, 2005-04) Zdansky, Jindrich
    This contribution proposes an efficient method for the detection of relevant changes in continuous stream of sound. The detected change-points can then serve for the segmentation of long audio recordings into shorter and more or less homogenous sections. First, we discuss the task of a single change-point detection using the Bayes decision theory. We show that it leads to a quite simple and computationally efficient solution based on the Bayesian Information Criterion. Next, we extend this approach to formulate the algorithm for the detection of multiple change-points. Finally, the proposed algorithm is applied for the segmentation of broadcast news audio-streams into parts belonging to different speakers or different acoustic conditions. Such segmentation is necessary as the first step in the automatic speech-to-text transcription of TV or radio news.
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    Generator of Time Series of Rain Attenuation: Results of Parameter Extraction
    (Společnost pro radioelektronické inženýrství, 2005-04) Grabner, Martin; Fiebig, Uwe-Carsten; Kvicera, Vaclav
    Rain attenuation has a significant impact on the availability of millimeter wave communication systems. In order to dynamically simulate such radio systems, several generators of artificial time series of rain attenuation have been developed. This paper briefly describes the DLR channel model and presents the results of model parameter extraction from time series measured on terrestrial microwave paths in the Czech Republic.
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    Impact of Ultra Wide Band (UWB) on Macrocell Downlink of DCS-1800 and GSM-900 Systems
    (Společnost pro radioelektronické inženýrství, 2005-04) Taha-Ahmed, Bazil; Calvo-Ramon, Miguel; de Haro-Ariet, Leandro
    The effect of UWB interference on the DCS-1800 and GSM-900 downlink is studied for different UWB power density. For high UWB power density (-70 dBm/MHz), the effect of UWB signals is very high when the distance between UWB transmitter and DCS-1800 receiver is less than 1 m. For low UWB power density (-100 dBm/MHz), the effect of the UWB signals is quasi null even if the distance between the UWB transmitter and the DCS-1800 receiver is 0.5 m. It is found that the spectrum mask proposed by the FCC for indoor application (-53 dBm/MHz in the DCS-1800 band and -41 dBm/MHz in the GSM-900 band) is very high to be tolerated by the two mobile systems and we have to propose another spectrum mask with lower UWB power density.