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Radioelektronika (RADIOELEKTRONIKA), 2010 20th International Conference

Date 19-21 April 2010

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Displaying Results 1 - 25 of 55
  • Changes in frequency spectrum of vowels due to psychological stress

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (430 KB) |  | HTML iconHTML  

    A significant part of information carried in speech signal refers to the speaker expressing their personality, transferring emotions, and reflecting situations such as fatigue, stress or some medical problems. This paper deals with speech signal spoken by speaker under psychological stress. A classification of various states of stress and the corresponding type of stressor is defined. For use in our experiments, a new database of speech under stress consisting of data collected during oral examinations at our university was created. Long-time changes of fundamental frequency and short-time changes in spectrum of vowels due to exam stress were investigated. The primary goal of the study reported here is to give an introduction to the problem “speaker's stress and speech signal”. View full abstract»

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  • Towards reliable speech recognition in operating room noise environment

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (457 KB) |  | HTML iconHTML  

    This paper describes several practical steps for accurate statistical modeling of a known acoustical noise environment to attain good performance of a small vocabulary speech recognizer for isolated words based on whole-word hidden Markov models. Hierarchical segmentation based on Bayes information criterion and k-means clustering followed by split-merge Gaussian mixture model training were utilized for noise model estimation. Parallel model combination technique produces final noise-corrupted speech models for a small group of speakers. Experiments were carried out on a real operating room ambient noise recorded during a neurosurgery at the University Hospital in Marburg. View full abstract»

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  • Performance of interpolation algorithms for PWM driven power amplifiers

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (382 KB) |  | HTML iconHTML  

    The new radio broadcasting standards as Digital Radio Mondiale (DRM) and HD Radio impose new demands on AM transmitters. Nowadays, two modulating designs dominate over the AM transmitter market - Pulse Width Modulation (PWM) technology and digital technology. In both cases, it is profitable to implement the modulator in all-digital form, which enables to use powerful DSP algorithms. This paper presents performance study of digital PWM generator, which is the key component of the PWM AM transmitters. As only the natural PWM is baseband distortion-free modulation scheme, the digital PWM generator must calculate the intersection of the modulating signal and a piecewise linear reference signal, requiring a low-distortion interpolating algorithm. Moreover, the digital PWM generator output stage must offer exceptional time resolution and low jitter. Therefore, the accuracy of interpolating algorithm and time resolution of PWM generator are surely the critical points of the digital PWM generator design. Both phenomena are discussed in this paper. The different interpolating algorithms are tested for Signal-to-Sampling Noise Ratio (SSNR) and the digital PWM generator time resolution impact on spectral properties is simulated. View full abstract»

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  • DVB-T and DVB-H measuring software for PC connected with spectral analyzer

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (458 KB) |  | HTML iconHTML  

    This contribution describes Digital Video Broadcasting-Terrestrial and Digital Video Broadcasting-Handheld measuring software for personal computer connected with a spectral analyzer. The free of charge software could upgrade a radio measurement laboratory, where a spectral analyzer is assumed as a one of basic devices, to measure some spectral and signal parameters and characteristics of above-mentioned systems. The main aim is to explain the processing of digital signal received samples and compare software features with a test receiver. Measuring software was developed and created during the diploma project. View full abstract»

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  • Modulator imperfections and I/Q errors influence on the DVB-T signal

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2889 KB) |  | HTML iconHTML  

    This paper deals with the modulator imperfections and I/Q errors influence on the DVB-T signal and its spectrum and I/Q constellation analysis. Theoretical backgrounds of the Amplitude Imbalance, Phase Error and Carrier Suppression effects are summarized in the paper. Then the practical results measured in the laboratory environment are compared with the theoretical assumed impacts on Modulation Error Rate from the I/Q constellation and Bit Error Rates before and after Viterbi decoding in DVB-T signal decoding. View full abstract»

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  • Performance of hiearichcal modulation in DVB-T

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (716 KB) |  | HTML iconHTML  

    This paper deals with hierarchical modulation technique that can be used in the DVB-T system. The purpose is to provide higher video quality in good receiving conditions and lower video quality in worse receiving conditions, while maintaining low BER rate needed for successful signal decoding. Hierarchical modulation technique is described as well as its simulation. Results of BER dependence on C/N ratio simulated in Matlab are compared to the results of laboratory measurement and are discussed. View full abstract»

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  • Comparison of native and In-depth Symbol interleaving used in DVB-T/H channel coding

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (325 KB) |  | HTML iconHTML  

    This paper presents two options of the Inner Symbol interleaving in channel coding of digital television DVB-T and DVB-H standards. Comparison and differences of both the Native and In-depth interleaving are outlined. There is also described MATLAB model of the transmission channel and simulation results of the DVB-H system working in an impulse noise conditions are presented. Comparison between the 2k, 4k and 8k transmission modes and different Symbol Interleaving choices are discussed considering specific mode application in DVB-T/H digital television systems. View full abstract»

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  • Simulation of the DVB-H channel coding and transmission in Matlab

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1149 KB) |  | HTML iconHTML  

    This paper deals with the Matlab implementation of the DVB-H (Digital Video Broadcasting to Handhelds) channel coding in AWGN (Additive White Gaussian Noise) transmission channel. Developed application structure and its functions are described. Channel encoder and decoder were implemented in Matlab as it is specified in the DVB-H standard. Created application can evaluate and shows two types of BER (Bit Error Ratio) - BER before Viterbi decoding and BER after Viterbi decoding. The OFDM (Orthogonal Frequency Division Multiplexing) modulation was not implemented yet. Finally, obtained results are evaluated and discussed. View full abstract»

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  • DVB-S/S2 satellite television broadcasting measurement and comparison

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1534 KB) |  | HTML iconHTML  

    This paper deals with an experimental measurement of real DVB-S and DVB-S2 signal. As a digital satellite signal source were used a 90cm diametric parabolic antenna in top of DREL BUT destined to satellite ASTRA 3A 23,5° East longitude for DVB-S signal and to satellite ASTRA 1E 19,2° East longitude for DVB-S2 signal. Antenna measurement system Kathrein MSK 200 was used as a test receiver for the measurement with a set top box Humax HD 2000-CI. Finally, obtained results are evaluated, compared and commented. View full abstract»

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  • Fuzzy logic based call admission control with user movement prediction for UMTS system

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (346 KB) |  | HTML iconHTML  

    Universal mobile telecommunications system (UMTS) is one of the 3rd generation (3G) cell phone technologies. The capacity of UMTS is interference limited. Radio resources management (RRM) functions are therefore used. They are responsible for supplying optimum coverage, ensuring efficient use of physical resources, and providing the maximum planned capacity. This paper deals with admission control techniques for UMTS system. A UMTS system model and several versions of admission control algorithms are presented in this paper. These algorithms are based on fuzzy logic and they use simple user movement prediction methods. The algorithms are mutually compared via simulations. View full abstract»

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  • Notes to multistage Wiener filter in DS-CDMA detector

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    The contribution follows report oriented towards design of Wiener filter in DS-CDMA detector of signals as a multistage structure. Such approach avoids evaluation of the inverse of a known autocorrelation matrix of a sampled response of the chip matched filter to a wide-sense stationary input signal. The contribution gives more detailed description of detector signal processing and its consequences. View full abstract»

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  • Impact of fragmentation threshold tuning on performance of voice service and background traffic in IEEE 802.11b WLANs

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB) |  | HTML iconHTML  

    This paper deals with measurements of the impact of fragmentation threshold tuning on speech quality and background traffic throughput in mixed voice/data transmission in an environment of WLANs (IEEE 802.11b). The ITU-T G.729AB encoding scheme is deployed in this study and the Distributed Internet Traffic Generator (D-ITG) is used for the purpose of the background traffic generation. The primary goal of generated background traffic is to affect the speech transmission by changing of VoIP connection network performance parameters such as jitter (delay variation), and packet loss. In general, those parameters have a significant impact on overall speech quality perceived by user. The speech quality and performance of background traffic are assessed by means of the accomplished PESQ algorithm and Wireshark network analyzer, respectively. This experiment shows that fragmentation threshold tuning can significantly decline speech quality and performance of background traffic. View full abstract»

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  • Refined iterative detection of coded SC-FDMA based transmission systems

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    Single Carrier Frequency Division Multiplex (SC-FDMA) is the modulation technique being considered in Long Term Evolution (LTE) proposal announced recently. The reason for this stems from the fact that SC-FDMA envelope fluctuation is considerable lower than that of conventional Orthogonal Frequency Division Multiplex (OFDM) technique, thereby results in less sensitivity to the nonlinear distortion introduced by the High Power Amplifiers (HPA). However, in order to achieve high spectrum and power efficiency of the transmission, it is convinient to look for additional strategies to further improve the SC-FDMA robustness against the nonlinear amplification. Therefore, in this paper we introduce the technique based on the iterative detection of nonlinearly distorted SC-FDMA symbols that aims to tackle the nonlinear distortion in an iterative fashion. The performance analysis show the considerable performance improvements of presented technique performing over frequency selective channels. View full abstract»

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  • Impact of the number of access points in indoor fingerprinting localization

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (582 KB) |  | HTML iconHTML  

    In the paper the solution for indoor positioning based on IEEE 802.11 platform is proposed and experimentally verified. The paper investigates an impact of the number of access points on the localization accuracy in fingerprinting method. The solution is based on deterministic approach. The properties of the solution are tested by experimental measurements in real environment. View full abstract»

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  • Evaluation of channel estimation error inflicted by nonlinear amplification and of its recovery by the means of iterative algorithm

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB) |  | HTML iconHTML  

    When high power amplifiers are in OFDM transmitters employed in the area of their nonlinear characteristics, the transmitters became more energy efficient and their consumption decreases. However, transmitted signal is nonlinearly amplified and therefore subject to nonlinear distortion. When assuming perfect channel state information present at the receiver, only data symbols are nonlinearly distorted, what results in a decreased performance. However, real world devices must obtain channel state information through estimation process, which is usually based on insertion of pilot symbols into transmission and subsequent pilot symbols channel estimation. In this case, also transferred pilot symbols are subject to nonlinear amplification and distortion, which lowers the accuracy of channel estimation process, and further decreases the transmission performance. This article concerns with evaluation of channel estimation error in a situation of nonlinear amplification, and with an improvement of channel estimation error by iterative algorithm of nonlinear distortion estimation, cancellation and channel reestimation. View full abstract»

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  • Signal processing for vector control of AC drive

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (502 KB) |  | HTML iconHTML  

    An induction motor with vector control has a very good dynamic behavior and as a consequence is well suited for high performance applications. But, the vector control is very sensitive to variations in the rotor time constant. In the paper there is presented signal processing for the vector control of an induction motor with rotor time constant adaptation using TMS320F2812 DSP. The method employs the model reference adaptive system. The estimated rotor time constant is necessary for so-called current model which is used in the vector control and serves for the determination of the quantities for the transformation from stationary reference frame into reference frame. At the end of the paper some experimental results are provided to demonstrate the effectiveness of realized signal processing. View full abstract»

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  • New unconventional reliability growth model

    Publication Year: 2010 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    The reliability growth model (RGM) is a very specific tool used during the development phase of electronic devices and software products. The new unconventional reliability growth models are based on the homogeneity testing of different Poisson process characteristics. This makes it possible to find the time frame for finishing the technological constructing operations for further reliability growth in the next design of an electronic object. We review one new unconventional reliability growth model of electronic devices in this paper. It is RGM algorithm based on Poisson process homogeneity testing of correlation function R(t1, t2). View full abstract»

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  • Real time processing in educational practice with help of TMS320C6713 DSP starter kit

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB) |  | HTML iconHTML  

    In this paper the application of fundamental algorithms for signal processing in educational domain are presented. The original motivation of the contribution is to show the possibilities of digital signal processors programming in education practice. The aim is approximate the author's experience with university students teaching. Mainly the using of floating-point digital signal processors to implement the C and assembly source code is outlined. The practical experiments bring students the deeper understanding of the microprocessor technique principles as well as the signal processing algorithms. In the text the short presentation of students' experiments with DSPs is outlined. Moreover the impact of programming in high-level and low-level languages, followed by the optimizing is proved as well. View full abstract»

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  • Using DCT coefficients flipping for information hiding in still images

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (677 KB) |  | HTML iconHTML  

    The paper deals with information hiding in general and special focus is given to information content hiding in still images. A solution of information hiding of protected part of an image within the image itself is also presented. Three approaches are proposed - digital watermarking, DCT coefficients flipping and cryptography. The main focus of this paper is oriented to information hiding based on DCT coefficients flipping. In this case the information content protection is based on pixelisation and mosaic approach. Some experimental results are shown and advantages and drawbacks are also discussed. View full abstract»

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  • Comparison of two watermarking methods based on DWT

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (310 KB) |  | HTML iconHTML  

    This paper describes a new method for video watermark embedding, using the knowledges already available from watermark embedding into digital static pictures. The watermark is embedded in transformed domain using Discrete Wavelet Transform (DWT). This paper also describes experiments conducted on the proposed watermark embedding method. The goal of these experiments was the test the robustness of the method presented in the paper against several watermarking attacks. View full abstract»

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  • Temporal-spatial error concealment algorithm for intra-frames in H.264/AVC coded video

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    Video communication through wireless channels is still a major problem due to the limitations in bandwidth and the presence of channel errors. The other limitations within the mobile networks is low transmission bit rate which demands the reduction of the used video resolution and a high efficient video compression technique. Video transmission in wireless environments is a challenging task calling for high-compression efficiency as well as a network-friendly design. The network-friendly design of H.264/AVC is addressed via the network abstraction layer that has been developed to transport the coded video data over any existing and future networks including wireless systems. Exploiting this feature, we present a modified temporal-spatial error concealment algorithm for H.264 coded video. Simulations were carried out in computing environment Matlab using the standard video-sequences. View full abstract»

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  • Simulation of packet losses in video transfers using real-time transport protocol

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    Multimedia content transmitted over unreliable environment, like wireless channels or in generally any network with unreliable transport protocol, is always subject to packet loss due to network congestion and channel noise. By using compressed video, errors could propagate to the subsequent frames with resulting worse video quality. Therefore it is necessary to study impact of packet loss on overall video quality. First step in such study is creation of network models. The most popular approach is network modeling using Markov chains. In our paper we have analyzed in which way have occurred packet losses during transmission of video through wired and also wireless network. View full abstract»

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  • Information hiding using pseudo-random number sequences with error correction

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (485 KB) |  | HTML iconHTML  

    In this paper, we present a novel method of steganography system based on CDMA (Code Division Multiple Access) approach having regard to perceptibility of stego-image. Also additional extraction algorithms were designed due to enhancing of secret message decomposition. As it will be shown later, aptly imposed features of CDMA techniques are in consonance with imperatives claimed upon steganography systems. View full abstract»

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  • Estimating a spectral correlation function and its errors owing to inexact frequencies

    Publication Year: 2010 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (965 KB) |  | HTML iconHTML  

    This paper is devoted to estimating a spectral correlation function using DFT. The examined signal is a simple DSB-SC signal. The aim of the paper is to analytically describe events connected with nonstandard relations between signal frequency parameters and sampling frequency. They manifest by descending the spectral correlation function modulus. Validity of the analytical description was verified using computer simulations for deviations of carrier frequency, cyclic frequency and both frequencies and variable number of the sliding DFT windows. Analysis of the errors is presented. An imperfection of the analytical relations is mostly insignificant. Founded equations are simple and allow judge consequences of the frequency faultiness without simulations. View full abstract»

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  • The 2D spreading based communication systems implementation using USRP

    Publication Year: 2010 , Page(s): 1 - 4
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    This paper deals with issues related with implementation of Variable Spreading Factor Orthogonal Frequency and Code Division Multiplexing (VSF-OFCDM) systems using Universal Software Radio Peripheral (USRP). Comparison of simulated and with USRP hardware achieved results of VSF-OFCDM systems with various 2D spreading factors (SF) are being done. Simulation of complete communication chain is being done but only the transmitter part was implemented and investigated using USRP. View full abstract»

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