This paper deals with the SIMULINK model of DVB–T system with parameters settled in Lithuania. Special attention has been given to the design of the tuner phase noise model. The simulation results are presented. The critical values of signal–to–noise ratio in the channel and phase noise level of the tuner determining the critical value of bit error rate were estimated. Ill. 5, bibl. 11 (in English; abstracts in English, Russian and Lithuanian).
This paper deals with the image encryption scheme based on non-linear dynamic chaotic system in stream cipher architecture. The narrowing of the numbers domain interval to [0.2, 0.8] and a double precision floating point format to encode float numbers to binary format were used for pseudo random stream generator. The results of the NIST statistical test suite and security analysis are given. The results show very good cryptographic properties and high security. Key-Words: Image encryption, Non-linear chaotic dynamic system, Stream generator, Security analysis, Cryptography.
This paper deals with the original construction of the cryptographic secure pseudo random number generator based on non-linear dynamic chaotic system. The narrowing of the numbers domain interval to [0.2, 0.8] and a double precision floating point formatting to encode float numbers to binary format were used for getting pseudo random bits. The results of the second level NITS tests for randomness of the proposed pseudo random bit generator (PRBG) are presented. They testify very good cryptographic properties of the proposed PRBG.
Modulation impulse shaping in conventional communication systems usually is realized by the root-raised-cosine filtering. Recently modulation impulse shaping on the basis of wavelet transform was proposed. The present paper deals with the use of quasiorthogonal sequencies for impulse shaping. The main objective is to design the SIMULINK models of communication systems with modulation impulse shaping on the basis of quasi-orthogonal sequencies, wavelets and root-raised-cosine filters and to evaluate the nonlinear amplification sensitivity and the performance of systems corrupted by noise. The main results are: the systems with quasiorthogonal sequences require more bandwith, the performance of them is is some what less and non-linear amplification sensitivity of them is notibly less comparing with other systems. Ill. 16, bibl. 7 (in Lithuanian; summaries in English, Russian and Lithuanian).
An investigation method of the functionality of user interface software for measuring devices is introduced and described. The software verification procedure using the proposed method is discussed as well.
Currently analogue technologies are presented in cable and terrestrial TV networks solely. Whereas rapid implementation of digital information technologies (IT) in television enables to provide new interactive services and analogue turn off (ATO) on the whole. The article deals with some aspects and conditions for DVB-T/C networks rollout and preconditions for ATO in Lithuania.
Currently analogue technologies are present in cable and terrestrial TV networks solely, whereas rapid implementation of digital information technologies (11) in television enables to provide new interactive services and analogue turn off (ATO) on the whole. The article deals with the development level of digital accesses as well as with preconditions for ATO and conditions for development of DVB networks in Lithuania.
All known technologies of digital accesses are applied or are going to be applied in Lithuania. The article introduces with a range ofmore advanced technologies: ADSL. VDSL, LMDS, GSM, UMTS, DVB-S, C, T, etc.. It is emphasized versatility of MPEG, DVB andMHP platform standards and creation of universal MHP set-top box (STB). Analysis of relationships among image quality, access bitrate capacity, transmission time, storage capacity and price for five image quality levels is presented. It is pointed out, that DVB-Ttechnology is the most acceptable for the strategical development of TV networks with full coverage of the country and withpossibilities to interactivity, mobility and Internet access downstream. Bibl. 4 (in Lithuanian; summaries provided in Lithuanian,English, and Russian).
Currently the world experiences revolutionary changes in the field of Information Technologies, which have resulted in the direct impact on Telecommunications and Audio-Visual (AV) markets. Analogue technologies remained only in cable and terrestrial broadcasting networks. But rapid implementation of digital technologies in this field enables to offer a wide range of new services including interactive ones. The article deals with the development level of the AV market in Lithuania, its expansion trends and development tendencies of digital accesses in terms of interactive technologies, possibilities, demand, competition, prices, etc. Bibl. 6 (in Lithuanian; summaries in Lithuanian, English and Russian).
This paper deals with measurement methods of the rms value of periodic signals based on frequency measurement and resampling, or interpolation of a signal. In this paper analytical expressions relating rms value measurement error and frequency measurement error are shown and computer-based simulation results are presented.
