2007/4

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    Multi-Carrier Modulation and MIMO Principle Application on Subscriber Lines
    (Společnost pro radioelektronické inženýrství, 2007-12) Vodrazka, Jiri
    The multi-carrier modulation is used in many applications, primary for a wireless transmission, for example Wi-Fi and WiMAX networks or DVB-T. But the same physical principle can be used also for metallic lines in access or local networks, for example ADSL and VDSL. The multi-carrier modulation in these cases is called DMT. The dominant source of noise in multi-pair metallic cables is crosstalk when the information capacity is limited dramatically. However, information capacity of metallic lines can be increased, if the system is using MIMO principles, concrete VDMT modulation and line bounding concept. The methods for VDMT modulation and partial crosstalk cancellation are discussed and simulation results are presented.
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    Novel Method for Color Textures Features Extraction Based on GLCM
    (Společnost pro radioelektronické inženýrství, 2007-12) Benco, Miroslav; Hudec, Robert
    Texture is one of most popular features for image classification and retrieval. Forasmuch as grayscale textures provide enough information to solve many tasks, the color information was not utilized. But in the recent years, many researchers have begun to take color information into consideration. In the texture analysis field, many algorithms have been enhanced to process color textures and new ones have been researched. In this paper the new method for color GLCM textures and comparing with other good known methods is presented.
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    Chip Interleaving and its Optimization for PAPR Reduction in MC-CDMA
    (Společnost pro radioelektronické inženýrství, 2007-12) Fedra, Zbynek; Marsalek, Roman; Sebesta, Vladimir
    This paper analyzes the usability of peak to average power ratio (PAPR) reduction in multicarrier code division multiple access (MC-CDMA) by the chip interleaving optimization. This means chip position formatting to PAPR minimization. One chip interleaving pattern is used for all users in system (all spreading sequences). Dependency on number of subcarriers and spreading sequence length is simulated. The impact on amplitude histogram is presented and relation to random interleaving pattern is shown.
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    The Use of Wavelets in Image Interpolation: Possibilities and Limitations
    (Společnost pro radioelektronické inženýrství, 2007-12) Dumic, Emil; Grgic, Sonja; Grgic, Mislav
    Discrete wavelet transform (DWT) can be used in various applications, such as image compression and coding. In this paper we examine how DWT can be used in image interpolation. Afterwards proposed method is compared with two other traditional interpolation methods. For the case of magnified image achieved by interpolation, original image is unknown and there is no perfect way to judge the magnification quality. Common approach is to start with an original image, generate a lower resolution version of original image by downscaling, and then use different interpolation methods to magnify low resolution image. After that original and magnified images are compared to evaluate difference between them using different picture quality measures. Our results show that comparison of image interpolation methods depends on downscaling technique, image contents and quality metric. For fair comparison all these parameters need to be considered.
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    New Watermarking Scheme for Security and Transmission of Medical Images for PocketNeuro Project
    (Společnost pro radioelektronické inženýrství, 2007-12) Chemak, Chokri; Lapayre, Jean Christophe; Bouhlel, Mohamed Salim
    We describe a new Watermarking system of medical information security and terminal mobile phone adaptation for PocketNeuro project. The later term refers to a Project created for the service of neurological diseases. It consists of transmitting information about patients \"Desk of Patients\" to a doctor\'s mobile phone when he is visiting or examining his patient. This system is capable of embedding medical information inside diagnostic images for security purposes. Our system applies JPEG Compression to Watermarked images to adapt them to the doctor\'s mobile phone. Experiments performed on a database of 30-256x256 pixel-sized neuronal images show that our Watermarking scheme for image security is robust against JPEG Compression. For the purpose of increasing the image Watermarking robustness against attacks for an image transmission and to perform a large data payload, we encode with Turbo-Code image-embedded bits information. Fidelity is improved by incorporation of the Relative Peak Signal-to-Noise Ratio (RPSNR) as a perceptual metric to measure image degradation.