O incremento das taxas de transmissão e de armazenamento demanda o desenvolvimento de técnicas para aumentar a taxa de compressão de imagens e ao mesmo tempo mantenha a qualidade destas imagens. O padrão JPEG2000 propõe a utilização da transformada wavelet discreta e codificação aritmética para alcançar altos graus de compressão, proporcionando que a imagem resultante tenha qualidade razoável. Este padrão permite tanto compressão com perdas como compressão sem perdas, dependendo apenas do tipo de transformada wavelet utilizada. Este trabalho propõe a implementação de blocos internos em hardware para compor um compressor de imagens com perdas seguindo o padrão JPEG2000. O principal componente deste compressor de imagens é a transformada wavelet discreta irreversível em duas dimensões, que é implementada utilizando um esquema lifting a partir dos coeficientes Daubechies 9/7 descritos na literatura. Para proporcionar altas taxas de compressão para a transformada irreversível, são utilizados coeficientes reais – que são originalmente propostos em representação de ponto-flutuante. Neste trabalho, estes coeficientes foram implementados em formato de ponto-fixo arredondado, o que resulta erros que foram estimados e controlados. Neste trabalho, várias arquiteturas em hardware para a descrição da transformada wavelet discreta irreversível em duas dimensões foram implementadas para avaliar a relação entre tipo de descrição, consumo de área e atraso de propagação. A arquitetura de melhor relação custo benefício requer 2.090 células de um dispositivo FPGA, podendo operar a até 78,72 MHz, proporcionando uma taxa de processamento de 28,2 milhões de amostras por segundo. Esta arquitetura resultou em um nível de erro médio quadrático de 0,41% para cada nível de transformada. A arquitetura implementada para o bloco do codificador de entropia foi sintetizada a partir de uma descrição comportamental, gerando um hardware capaz de processar até 843 mil coeficientes de entrada por segundo. Os resultados indicam que o compressor de imagens com perdas seguindo o padrão JPEG2000, utilizando os blocos implementados nesta dissertação e operando na máxima freqüência de operação definida, pode codificar em média 1,8 milhões de coeficientes por segundo, ou seja, até 27 frames de 256x256 pixels por segundo. Esta limitação na taxa de codificação é definida pelo codificador de entropia, que possui um algoritmo mais complexo, necessitando de um trabalho complementar para melhorar sua taxa de codificação aumentando o paralelismo do hardware. / The increasing demands for higher data transmission rates and higher data storage capacity call for the development of techniques to increase the compression rate of images while at the same time keeping the image quality. The JPEG2000 Standard proposes the use of the discrete wavelet transform and of arithmetic coding to reach high compression rates, providing reasonable quality to the resulting compressed image. This standard allows lossy as well as loss-less compression, dependent on the type of wavelet transform used. This work considers the implementation of the internal hardware blocks that comprise a lossy image compressor in hardware following the JPEG2000 standard. The main component of this image compressor is the two dimensional irreversible discrete wavelet transform, that is implemented using a lifting scheme with the Daubechies 9/7 coefficients presented in the literature. To provide high compression rates for the irreversible transform, these coefficients – originally proposed in their floating-point representation – are used. In this work, they are implemented as fixed-point rounded coefficients, incurring in errors that we estimate and control. In this work, various hardware architectures for the two dimensional irreversible discrete wavelet transform were implemented to evaluate the tradeoff between the type of description, area consumption and delay. The architecture for the best trade-off requires 2,090 logic cells of a FPGA device, being able to operate up to 78.72 MHz, providing a processing rate of 28.2 million of samples per second. This architecture resulted in 0.41% of mean quadratic error for each transformed octave. The architecture implemented for the block of the entropy encoder was synthesized from a behavioral description, generating the hardware able to process up to 843 thousands of input coefficients per second. The results indicate that the lossy image compressor following JPEG2000 standard, using the blocks implemented in this dissertation and operating in the maximum clock frequency can codify, in average, 1.8 million coefficients per second, or conversely, up to 27 frames of 256x256 pixels per second. The rate-limiting step in this case is the entropy encoder, which has a more complex algorithm that needs further work to be sped up with more parallel hardware.

The main aim of this project is to implement two different types of the watermarking algorithm in frequency (transforamtion) domain. Because of the huge amount of the watermarking algorithms is this thesis dedicated to the watermarking methods in the frequency domain. These methods use kind of transformation implemented on the original data, the second step is modification of transformation coeficients. This project is dedicated to the methods which use discrete wavelet transformation. Nowdays the most popular transformation, which meets the best efforts. The aim of every method is to embeed the watermark into the original data so precisly, that none observer can recognize any change between the original and watermarked data. On the contrary, watermarked picture should be as resistant to the attacks as possible. By the term of attack, we understand all the ways, that disable watermark extraction. The watermark method robustness will be tested with the use of Checkmark program.

No / In this work, we discuss two new multicarrier modulating kernels that can be adopted for multicarrier signaling. These multicarrier transforms are the fractional Forurier transform (FrFT) and discrete wavelet transforms (DWT). At first, we relate the transforms in terms of mathematical relationships, and then using numerical and simulation comparisons we show their performances in terms of bit error ratio (BER) for Multiple Input Multiple Output (MIMO) applications. Numerical results using BPSK and QPSK support that both can be applied for multicarrier signaling, however, it can be resource effective to drive the DWT as the baseband multicarrier kernel at the expense of the FrFT

No description available.

No / We have studied the performance of multidimensional signaling techniques using wavelets based modulation within an orthogonally multiplexed communication system. The discrete wavelets transform and wavelet packet modulation techniques have been studied using Daubechies 2 and 8, Biothogonal1.5 and 3.1 and reverse Biorthognal 1.5 and 3.1 wavelets in the presence of Rayleigh multipath fading channels with AWGN. Results showed that DWT based systems outperform WPM systems both in terms of BER vs. SNR performance as well as processing. The performances of two different equalizations techniques, namely zero forcing (ZF) and minimum mean square error (MMSE), were also compared using DWT. When the channel is modeled using Rayleigh multipath fading, AWGN and ISI both techniques yield similar performance.

Effective image compression requires a non-expansive discrete wavelet transform (DWT) be employed; consequently, image border extension is a critical issue. Ideally, the image border extension method should not introduce distortion under compression. It has been shown in literature that symmetric extension performs better than periodic extension. However, the non-expansive, symmetric extension using fast Fourier transform and circular convolution DWT methods require symmetric filters. This precludes orthogonal wavelets for image compression since they cannot simultaneously possess the desirable properties of orthogonality and symmetry. Thus, biorthogonal wavelets have been the de facto standard for image compression applications. The viability of symmetric extension with biorthogonal wavelets is the primary reason cited for their superior performance. Recent matrix-based techniques for computing a non-expansive DWT have suggested the possibility of implementing symmetric extension with orthogonal wavelets. For the first time, this thesis analyzes and compares orthogonal and biorthogonal wavelets with symmetric extension. Our results indicate a significant performance improvement for orthogonal wavelets when they employ symmetric extension. Furthermore, our analysis also identifies that linear (or near-linear) phase filters are critical to compression performance---an issue that has not been recognized to date. We also demonstrate that biorthogonal and orthogonal wavelets generate similar compression performance when they have similar filter properties and both employ symmetric extension. The biorthogonal wavelets indicate a slight performance advantage for low frequency images; however, this advantage is significantly smaller than recently published results and is explained in terms of wavelet properties not previously considered. / Master of Science

Made available in DSpace on 2016-03-15T19:37:47Z (GMT). No. of bitstreams: 1 Luiz Carlos Bernardo.pdf: 7288586 bytes, checksum: b7562f834db8a5ce808707075e7ce04b (MD5) Previous issue date: 2013-06-14 / A chaotic signal based communication system represents a new wideband transmission model. Nonetheless, chaotic based systems have not yet shown a distinguished performance in terms of bit error rate when transmitted in narrow band channels or in the presence of impairments in comparison to the traditional communications systems. The focus of this work relies on an experiment that overcomes this issue, through the conjugation of the characteristics of traditional communications based in orthogonal carriers and those originated from chaotic signals. More clearly, the chaotic modulation is employed in sub-carriers of traditional OFDM (Orthogonal Frequency Division Multiplexing). This novel modulation scheme is implemented through the generation of chaotic sequences in a one dimensional map controlled by a parameter p which defines the central region of the map as a guard interval, the slope of the delimiting lines and the chaotic behavior of the generated sequence. This parameter also determines directly the amplitude of each symbol, making it more irregular and less predictable, avoiding the detection by eavesdroppers and increasing the security level of the link to be transmitted. Besides the change in the traditional OFDM modulator from 4QAM to chaotic one, the Fast Fourier Transform (IFFT /FFT) will be replaced by Wavelets Transform IDWT/DWT), in order to overcome some conventional OFDM s disadvantages Additionally a quadrature chaotic OFDM system was conceived, where the chaotic modulation was performed in a constellation I and Q that was submitted to the same channel conditions as the previous one. Both systems were simulated in a MATLAB® environment using the built in functions at the Communications System Toolbox and its behavior analyzed using the BER-Bit error rate versus SNR-Signal noise ratio. The obtained results were reported and scrutinized. / Sistemas de comunicações baseados em sinais caóticos representam um novo campo de estudo de transmissão em banda larga. Entretanto, sistemas baseados em sinais caóticos não apresentaram ainda um desempenho distinto em termos de taxa de erro, quando transmitidos em canais sem fios ou na presença de interferências em comparação aos sistemas tradicionais. O foco deste trabalho está na proposta de um novo esquema obtido através da conjugação das características da comunicação tradicional baseada em subportadoras ortogonais e aquelas originadas por sinais caóticos. Mais precisamente, a modulação caótica é empregada nas subportadoras de um sistema OFDM (Multiplexação por Divisão de Frequência Ortogonal) tradicional. Este novo modelo de modulação é implementado através de geração de sequências caóticas em um mapa unidimensional controlado por um parâmetro p que define uma região central do mapa como um intervalo de guarda e, por conseguinte, o comportamento caótico da sequência gerada. Este parâmetro também determina diretamente a amplitude de cada símbolo, fazendo-o mais irregular e menos previsível, evitando a detecção por pessoal não autorizado, possibilitando o aumento do nível de segurança da transmissão. Além da mudança no modulador do OFDM convencional de 4QAM para caótico, ter-se-á a substituição da Transformada Rápida de Fourier (IFFT/FFT), largamente utilizada em sistemas OFDM pela Transformada Wavelet (IDWT/DWT), de maneira a aprimorar os pontos fracos do sistema OFDM convencional. Como contribuição adicional, tem se a concepção do sinal com modulação simbólica em quadratura, ou seja, uma parte do sinal foi gerada no eixo I e a outra parte no eixo Q, criando uma modulação caótica em quadratura que é submetida aos mesmos canais da modulação caótica anterior. Os sistemas propostos foram simulados em ambiente MATLAB® utilizando-se de funções pré-existentes no modulo de ferramentas de comunicações (Communications System Toolbox) e o seu comportamento analisado em termos de gráficos que representam a relação da taxa de erro do bit (BER) versus relação sinal ruído (SNR). Os resultados obtidos foram reportados e debatidos.

This thesis deals with a description of the industrial machine of the DWT (drywall tape) rewinder. The winder rewinds and cuts the drywall tape tape into smaller tapes, that are then sold. The first part contains a description of the winder, its structure and functions of its individual parts. The second part contains a description of the control system and the power wiring of winder. The next section contains a description of programming and setting of PLC, frequency inverters, and touch panel. Some modifications are then described when putting the winder into operation. The winder has been successfully implemented and built into a continuous shift operation. However, the development of the rewinder continues to improve its features and user-friendliness.

In recent years, there has been a rise of interest in the use of various spectral methods in economics and econometrics. These methods have their theoretical background in mathematics, particularly in Fourier analysis. The less tradi- tional and relatively new branch of methods stems from the so-called wavelet analysis. Wavelet methods are believed to have a wide applicability in the anal- ysis of economic time series. The motivation for this thesis is to introduce these methods and apply them in the analysis of economic problems, thereby showing their usefulness within the economic context. Particular attention is paid to band spectrum regression, which allows for decomposition of economic relation- ships into different frequency components. In this work, we use wavelet band spectrum regression, among other wavelet methods, to analyze the relation- ship between realized and implied volatilities for the price of crude oil. Second application is from the field of macroeconomics. We analyze the relationship between unemployment and labor productivity growth for four major European economies. 1

The delimitation of the very fines lithologies from seismic data is a crucial problem in geophysics, indeed the presence of the noise in seismic traces can deteriorate information and hide important hydrocarbons accumulations. For that we have to try in this paper to use a recent technique developed by A.Arneodo and his collaborators which is the wavelet transform modulus maxima lines (WTMM) combined with the discrete wavelet transform (DWT), to denoising traces and characterize each amplitude in the seismic trace by an exponent of Holder. In order to separate information that is of a significant geological lithology variation with the various noises. Our application at VSP data shows that this technique is a powerful tool of processing.