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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Adaptive techniques for multiband parameter estimation and extraction

Sun, Hanwu January 1996 (has links)
No description available.
2

Um estudo sobre filtros IIR adaptativos com aplicação a uma estrutura polifásica. / A study about adaptive IIR filters with application to a polyphase structure.

Burt, Phillip Mark Seymour 11 April 1997 (has links)
Neste trabalho faz-se um estudo sobre filtros IIR adaptativos e é apresentada uma estrutura polifásica para filtragem IIR adaptativa, que, em troca de um aumento de complexidade computacional, pode apresentar características mais favoráveis do que a estrutura direta comumente usada. O aumento da complexidade computacional, relativamente a um algoritmo do tipo newton, por exemplo, é pequeno. Apresenta-se uma análise dos efeitos da proximidade ao círculo unitário dos pólos do sistema sendo modelado. Um dos efeitos considerados é o comportamento limite do condicionamento da matriz de estados associada ao algoritmo de adaptação. São considerados algoritmos de adaptação de passo constante de uso comum para filtros IIR adaptativos. O método utilizado é particularmente útil para a verificação do efeito da posição dos pólos do sistema sendo modelado e também para a introdução de certas restrições ao mesmo, como, por exemplo, norma L2 fixa e resposta em freqüência passa-tudo. Um resultado interessante é que a única situação, entre as testadas, em que o condicionamento da matriz mencionada não tende a infinito quando um número qualquer de polosndo sistema sendo modelado H(z) se aproxima da circunferência unitária, é quando H(z) é passa-tudo e emprega-se o algoritmo PLR. São analisadas também a superfície de erro e a superfície de erro reduzida para filtros IIR adaptativos. Mostra-se que, quando o sistema sendo modelado possui polos próximos à circunferência unitária, a superfície de erro reduzida apresenta regiões planas com erro quadrático médio elevado. A existência destas regiões resulta em uma baixa velocidade de convergência global de algoritmos de passo constante. A partir da decomposição em valores singulares (SVD) da forma de Hankel do sistema sendo modelado, é apresentada também uma decomposição da superfície de erro reduzida, a partir da qual pode-se obter uma separaçãoparcial dos efeitos do sistema sendo modelado e da forma de realização do filtro adaptativo. Uma estrutura polifásica para filtragem IIR adaptativa é apresentada e seu desempenho é comparado com o de filtros IIR adaptativos na forma direta. Mostra-se o possível ganho da estrutura polifásica quanto à velocidade de convergência local e quanto às características da superfície de erro reduzida e à velocidade de convergência global. Demonstra-se, para a estrutura polifásica, que, com entrada branca e modelamento suficiente, todos os pontos estacionários da superfície de erro são mínimos globais da mesma. Este resultado não decorre diretamente de propriedades análogas relativas à estrutura direta, já conhecidas. Tudo para a estrutura direta quanto para a estrutura polifásica, são apresentados os resultados de várias simulações dos algoritmos de adaptação considerados. / A study on IRR adaptive filters and polyphase structure for IIR adaptive filtering are presented. In exchange for an increase in computational complexity, which is small if compared to Newton algorithms, the polyphaser structure may exhibit a better performance than direct structures. An analysis of the effects of the proximity to the unit circle of the modelled system\'s poles is presented. One of the considered points is the limiting behavior of the condition of the state matrix related to the adaptive algorithm. Commonly used constant gain algorithms are considered. The method of analysis is specially usefull for verifying the effects of the position of the system\'s poles and also for introducing certain restrictions to the system, as fixed L2 norm and all-pass frequency response. An interesting result is that, among the situations that were tested, the only one in which the condition of the aforementioned matrix does not tend to infinity as the poles of the modelled system H(z) tend to the unit circle is when H)z) is all-pass and the PLR algorithm is employed. The error surface and the reduced error surface for IIR adaptive filters are also analyzed. It is shown that the modelled system has poles close to the unit circle the reduced error surface presents flat regions with high mean square error. The presence of these flat regions results in low global convergence speed for constant gain adaptive algorithms. Based on the singular value decomposition (SVD) of the modelled system\'s Hankel form, a decomposition of the reduced error surface is also presented. In it there exists a partial separation of the effects of the system and the adaptive filter\'s structure. A polyphaser structure for IIR adaptive filtering is presented and its performance is compared to the performance of the direct structure. The gain in local convergence and global convergencespeed, as well as the better behavior of the reduced error surface which may be attained , are shown. It is demonstrated, for the polyphaser structure, that, with while input and sufficient modelling, all the stationary points of the error surface are global minima. This result does not follow directly from similar well known results for the direct structure. Simulation results for the considered algorithms are also presented.
3

Um estudo sobre filtros IIR adaptativos com aplicação a uma estrutura polifásica. / A study about adaptive IIR filters with application to a polyphase structure.

Phillip Mark Seymour Burt 11 April 1997 (has links)
Neste trabalho faz-se um estudo sobre filtros IIR adaptativos e é apresentada uma estrutura polifásica para filtragem IIR adaptativa, que, em troca de um aumento de complexidade computacional, pode apresentar características mais favoráveis do que a estrutura direta comumente usada. O aumento da complexidade computacional, relativamente a um algoritmo do tipo newton, por exemplo, é pequeno. Apresenta-se uma análise dos efeitos da proximidade ao círculo unitário dos pólos do sistema sendo modelado. Um dos efeitos considerados é o comportamento limite do condicionamento da matriz de estados associada ao algoritmo de adaptação. São considerados algoritmos de adaptação de passo constante de uso comum para filtros IIR adaptativos. O método utilizado é particularmente útil para a verificação do efeito da posição dos pólos do sistema sendo modelado e também para a introdução de certas restrições ao mesmo, como, por exemplo, norma L2 fixa e resposta em freqüência passa-tudo. Um resultado interessante é que a única situação, entre as testadas, em que o condicionamento da matriz mencionada não tende a infinito quando um número qualquer de polosndo sistema sendo modelado H(z) se aproxima da circunferência unitária, é quando H(z) é passa-tudo e emprega-se o algoritmo PLR. São analisadas também a superfície de erro e a superfície de erro reduzida para filtros IIR adaptativos. Mostra-se que, quando o sistema sendo modelado possui polos próximos à circunferência unitária, a superfície de erro reduzida apresenta regiões planas com erro quadrático médio elevado. A existência destas regiões resulta em uma baixa velocidade de convergência global de algoritmos de passo constante. A partir da decomposição em valores singulares (SVD) da forma de Hankel do sistema sendo modelado, é apresentada também uma decomposição da superfície de erro reduzida, a partir da qual pode-se obter uma separaçãoparcial dos efeitos do sistema sendo modelado e da forma de realização do filtro adaptativo. Uma estrutura polifásica para filtragem IIR adaptativa é apresentada e seu desempenho é comparado com o de filtros IIR adaptativos na forma direta. Mostra-se o possível ganho da estrutura polifásica quanto à velocidade de convergência local e quanto às características da superfície de erro reduzida e à velocidade de convergência global. Demonstra-se, para a estrutura polifásica, que, com entrada branca e modelamento suficiente, todos os pontos estacionários da superfície de erro são mínimos globais da mesma. Este resultado não decorre diretamente de propriedades análogas relativas à estrutura direta, já conhecidas. Tudo para a estrutura direta quanto para a estrutura polifásica, são apresentados os resultados de várias simulações dos algoritmos de adaptação considerados. / A study on IRR adaptive filters and polyphase structure for IIR adaptive filtering are presented. In exchange for an increase in computational complexity, which is small if compared to Newton algorithms, the polyphaser structure may exhibit a better performance than direct structures. An analysis of the effects of the proximity to the unit circle of the modelled system\'s poles is presented. One of the considered points is the limiting behavior of the condition of the state matrix related to the adaptive algorithm. Commonly used constant gain algorithms are considered. The method of analysis is specially usefull for verifying the effects of the position of the system\'s poles and also for introducing certain restrictions to the system, as fixed L2 norm and all-pass frequency response. An interesting result is that, among the situations that were tested, the only one in which the condition of the aforementioned matrix does not tend to infinity as the poles of the modelled system H(z) tend to the unit circle is when H)z) is all-pass and the PLR algorithm is employed. The error surface and the reduced error surface for IIR adaptive filters are also analyzed. It is shown that the modelled system has poles close to the unit circle the reduced error surface presents flat regions with high mean square error. The presence of these flat regions results in low global convergence speed for constant gain adaptive algorithms. Based on the singular value decomposition (SVD) of the modelled system\'s Hankel form, a decomposition of the reduced error surface is also presented. In it there exists a partial separation of the effects of the system and the adaptive filter\'s structure. A polyphaser structure for IIR adaptive filtering is presented and its performance is compared to the performance of the direct structure. The gain in local convergence and global convergencespeed, as well as the better behavior of the reduced error surface which may be attained , are shown. It is demonstrated, for the polyphaser structure, that, with while input and sufficient modelling, all the stationary points of the error surface are global minima. This result does not follow directly from similar well known results for the direct structure. Simulation results for the considered algorithms are also presented.
4

THE NEXT GENERATION AIRBORNE DATA ACQUISITION SYSTEMS. PART 1 - ANTI-ALIASING FILTERS: CHOICES AND SOME LESSONS LEARNED

Sweeney, Paul 10 1900 (has links)
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The drive towards higher accuracy and sampling rates has raised the bar for modern FTI signal conditioning. This paper focuses on the issue of anti-alias filtering. Today's 16-bit (and greater resolution) ADC’s, coupled with the drive for optimum sampling rates, means that filters have to be more accurate and yet more flexible than ever before. However, in order to take full advantage of these advances, it is important to understand the trade-offs involved and to correctly specify the system filtering requirements. Trade-offs focus on: • Analog vs. Digital signal conditioning • FIR vs. IIR Digital Filters • Signal bandwidth vs. Sampling rate • Coherency issues such as filter phase distortion vs. delay This paper will discuss each of these aspects. In particular, it will focus on some of the advantages of digital filtering various analog filter techniques. This paper will also look at some ideas for specifying filter cut-off and characteristics.
5

A Time Correlated Approach to Adaptable Digital Filtering

Grossman, Hy, Pellarin, Steve 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / Signal conditioning is a critical element in all data telemetry systems. Data from all sensors must be band limited prior to digitization and transmission to prevent the potentially disastrous effects of aliasing. While the 6th order analog low-pass Butterworth filter has long been the de facto standard for data channel filtering, advances in digital signal processing techniques now provide a potentially better alternative. This paper describes the challenges in developing a flexible approach to adaptable data channel filtering using DSP techniques. Factors such as anti-alias filter requirements, time correlated sampling, decimation and filter delays will be discussed. Also discussed will be the implementation and relative merits and drawbacks of various symmetrical FIR and IIR filters. The discussion will be presented from an intuitive and practical perspective as much as possible.
6

POLYNOMIAL BASED RECURSIVE AND NON RECURSIVE FILTER DESIGN

Kumar, Vinay 20 March 2009 (has links) (PDF)
In this dissertation, several algorithms to design linear phase Finite Impulse Response (FIR) and Infinite Impulse Response (IIR) filters have been discussed.<br /> Contrary to various already existing standard algorithms,the proposed methods approximate magnitude and phase characteristics simultaneously. The basic mechanism used in this study is polynomial based design of digital filters. We have used several already existing polynomials; e.g., Chebyshev polynomials, Legendre polynomials, to develop linear phase digital filters and developed some two dimensional polynomials following orthogonal properties to design digital filters for image processing, their design methodology have also been discussed.<br /> Filters of proposed type can be used for applications where exact linear phase is required. Another application of this type of filters is the design of filters with zero group delay. IIR filters are designed with absolute linear phase and zero group delay.<br /> The algorithms proposed in the present thesis allow user to design filters with his set of constraints, which is required in practical filter design problems. Very narrow band 1D and 2D linear phase FIR filters can easily be designed by the proposed methodology. The IIR filters proposed provide the guarantee to result in a stable filter.<br /> All the algorithms have been discussed stepwise to make sure that any one with basic programming capability can easily design them. We have not used any standard routine of any particular platform, therefore any freely available programming platform (like C, C++, Scilab, Octave, etc.) can be used to design these filters.
7

Využití techniky C2H při implementaci algoritmů pro FPGA / IMPLEMENTING ALGORITHMS ON FPGA UTILIZING C2H TECHNIQUE

Otisk, Libor January 2012 (has links)
This thesis deals with utilizing C2H technique for implementation algorithm on FPGA. Several structures of digital filters FIR and IIR are implemented within this work with usage of C2H. For such a comparison is in terms of FPGA resources utilized, the maximum frequency, latency, complexity of implementation and acceleration obtained to Nios II processor itself. Example for image processing using local operators implemented using C2h is also created to display the result on the LCD.
8

Prostředí pro verifikaci digitálních filtrů / Software for digital filter verification

Tesařík, Jan January 2016 (has links)
Diploma thesis deals with design of verification environment for analyzing systems with digital filters. Verification environment is written in SystemVerilog language and it is generated by program, which is also providing generation of input data for system of filters. Matlab environment is used for gaining the reference data. The simulation of the designed involvement with digital filters is performed by program ModelSim. The most watched parameter is functional coverage which indicates how big part of the HDL description has been tested.
9

A VLSI-nMOS hardware implementation of an IIR bandpass orthogonal digital filter

Kaake, Fadi M. January 1986 (has links)
No description available.
10

Optimising IIR Filters Using ARM NEON

Bentmar Holgersson, Sebastian January 2012 (has links)
ARMs processorserie Cortex-A9 har stöd för SIMD-instruktioner med hjälp av NEON MPE. Detta innebär att processorn kan använda sig av vektor-instruktioner som kan utföra operationer på ett flertal element med varje instruktion. Målet med bruk av NEON MPE är att öka prestandan, men då man försöker optimera en speciell IIR-filtertyp som kallas för "biquads" kan man stöta på problem. Problemen med NEON-optimering av "biquads" beror på att endast fem operationer krävs för varje iteration och att behandling av IIR-filter kräver att man behandlar en sampel i taget eftersom varje behandlat sampels värde beror på tidigare behandlade samplar. Rapporten ger en kort beskrivning och genomgång av hur IIR-filter och NEON-optimering fungerar.För att analysera NEON-optimering av biquad-filter skapas fyra olika implementationer av en audioeffekt. De fyra implementationerna jämför prestandan hos flyttalsaritmetik, fixpunkts-aritmetik och NEON-optimering samt en version som implementerar både fixpunktsaritmetik och NEON-optimering. Problemen med optimering av biquad-filter med hjälp av NEON-instruktioner löses genom parallell behandling av ljudkanalerna. Eftersom kanalerna är självständiga kan man fördubbla prestanda genom att utföra varje operation på såväl höger- som vänsterkanal. Vidare prestandaförbättring ges även då effektiviteten hos minnesoperationer förbättras och med hjälp av fixpunkts-behandling.Resultaten visar att fixpunktsversionen som använder sig av NEON-instruktioner är snabbast, men flyttalsversionen med NEON-instruktioner är bara marginellt långsammare och dessutom enklare att implementera. Användandet av NEON-instruktioner förbättrar prestandan med mellan 1,7-2,8 gånger i de fall som testas. / The ARM Cortex-A9 CPU has a SIMD extension called NEON MPE. It allows for vector instructions that can perform operations on multiple elements in a single instruction. Whilst this usually improves performance, certain IIR filters called biquads pose problems as only five operations are necessary per sample and every iteration is dependent on the result of the previous result. A brief overview is given for IIR filters, the NEON extension and fixed-point processing.In order to analyse optimisation of biquad filters, an audio effect with four different implementations is produced, comparing results with/without fixed-point processing and with/without NEON optimisation. The problems introduced by the use of biquad filters are solved by running multiple channels in parallel. As the audio channels are independent, two samples can be calculated in parallel, which approximately doubles peformance. Further performance improvement is provided by improved memory operation efficiency and the use of fixed-point processing.The results show that the fixed-point NEON implementation is the fastest, however the floating-point NEON implementation is marginally slower but simpler to write. The use of NEON MPE improves performance by between 1.7 to 2.8 times in this case.

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