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This paper deals with signal attenuation in ultra-high-frequency bands caused by rain. We focus mainly on the effect of the rain on the radio waves propagation in the frequency band 2.1 GHz. Two exact approaches for investigating this dependency are used. In the first approach, we use the fitting probability density function for determination Rician distribution Kfactor. In the second approach, we want tofind more concrete rain-rate dependency with using linear regression. The results achieved in our long-term investigation clearly indicate that the strong impact of rain itself is a minor. So-called secondary rain impacts such as scattering of reflections from wet surfaces cause the main attenuation contribution. [ABSTRACT FROM AUTHOR]

In this paper, a developed point-to-point wireless link using Universal Software Radio Peripheral (USRP) is presented. The aim of the research is focused on the monitoring and analysing the transmission characteristics on the physical layer of such wireless communication link with the consideration that these parameters could be affected by atmospheric phenomenon and air pollution. For that reason, the wireless link is situated to heavily loaded environment of Ostrava agglomeration where it is assumed extreme atmospheric phenomena such as smog or inverse situation. In the next part, a developed application which perform a fully automatic long term measurement of the transmission characteristics using a wireless link is presented. Finally, the first experimental results based on mathematical regression are presented. [ABSTRACT FROM AUTHOR]

This paper considers an issue of signal coverage in uncovered places using a broadcasting device called a Gap Filler. The main focus is placed on the analysis of potential negative effects while signals from two and more primary transmitters simultaneously enter to the Gap Filler. In particular, in the measurements the impact of reception cross delayed signals received by the Gap Filler from two adjacent primary transmitters operating in the Single Frequency Network was analysed. The influence of different receive signal levels from two adjacent primary transmitters was also examined. In the conclusion, based on the experiments, the limiting factors useful for individual transmitters in the Single Frequency Network were determined. The analysis and finding the limit parameters can help broadcasters in further setting and debugging of the Gap Filler network. Finally, the described laboratory experiment was also verified under the real SFN network condition in border region Vsetinsko to verify the laboratory findings. [ABSTRACT FROM AUTHOR]

In this article, we describe the performance evaluation of INACT tool which is developed for cataloguing of high-level and low-level metadata of the evidence material. INACT tool can be used by police forces in the cases of prosecution of such crimes as as possession and distribution of child pornography (CP). In live forensic cases, the time to first hit (time when the first image containing e.g. CP is found) is important, as then further legal actions are justified (such as arrest of the suspect and his hardware). The performance evaluation of first hit was performed on real data with the cooperation of Czech Police, Department of Internet Crime. [ABSTRACT FROM AUTHOR]

This article brings in the second part general information about half-wave impedance repeater. The third part describes the basic functional principles of the half-wave impedance repeater using Smith chart. The main attention is focused in part four on the derivation of repeater frequency bandwidth depending on characteristics and load impedance of unknown feeder line. Derived dependences are based on the elementary features of the feeder lines with specific length. The described functionality is proved in part 4.3 by measurement of transformed impedance using vector several unbalanced feeder lines and network analyzer VNWA3+. [ABSTRACT FROM AUTHOR]