The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
Markku Renfors - One of the best experts on this subject based on the ideXlab platform.
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decimation by non Integer Factor in multistandard radio receivers
Signal Processing, 2005Co-Authors: D Babic, Markku RenforsAbstract:In many applications it is required to have a system for non-Integer sampling rate conversion (SRC), which supports any decimation Factor, and provides enough attenuation for aliasing and imaging signal components. A good example case is a software radio receiver, where the ratio of sampling rate just after A/D converter and symbol rate for a supported standard may be a ratio of two large mutually prime numbers. In a digital mobile receiver, it is very important to reduce the power consumption. The power consumption in context of SRC can be reduced by designing a system that has low rate of multiplication and addition operations.This paper introduces a novel non-Integer decimation method. The proposed structure is a combination of an FIR filter and a polynomial-based interpolation filter. For the special case based on a cascaded integrator-comb (CIC) filter and simple polynomial-based interpolation filter, the proposed combination has a very efficient implementation structure. The results shown in this paper indicate that the computational complexity and multiplication rate can be reduced compared to the earlier solutions.
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decimation by non Integer Factor in software radio receivers
Facta universitatis. Series electronics and energetics, 2003Co-Authors: D Babic, Markku RenforsAbstract:The sampling rate conversion is a critical functionality of the software radio receiver. Because the signals of different system standards have incommensurate symbol/sampling rates and a common Analog-to Digital Converter (ADC) is to be used for all supported standards, the decimation Factor may become very difficult non-Integer number. This paper gives overviews and comparisons of two efficient fractional decimator structures based on Cascaded Integrator-Comb (CIC) filters and low order polynomialbased interpolation filters.
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EUSIPCO - Programmable modified fractional comb decimation filter
2002Co-Authors: D Babic, Markku RenforsAbstract:In multistandard radio receivers, the hardware should be configurable or programmable for the reception of different types of signals having different symbol rates. The decimation by a non-Integer Factor becomes a critical functionality of the multistandard radio. The Cascaded Integrator-Comb (CIC) filters are commonly used for decimation by an Integer. By using polynomial interpolation filter between integrator and comb stages of CIC, and non-Integer delay in the feed-forward branch of the comb stage, we achieve improved attenuation for the aliasing frequency components, and we make possible to use this type of structure for decimation by a non-Integer Factor. We name this structure as a programmable fractional CIC filter structure. This paper presents an efficient fractional structure for flexible decimation in the multistandard radio receivers. This structure is based on the so-called modified comb filter using the programmable fractional CIC principle. The main advantages of the proposed structure are flexibility and programmability with increased attenuation for aliasing frequency components.
M J Bastiaans - One of the best experts on this subject based on the ideXlab platform.
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gabor s signal expansion and the zak transform with oversampling by an Integer Factor
IEEE Transactions on Signal Processing, 1995Co-Authors: M J Bastiaans, M C W GeilenAbstract:Gabor's expansion of a signal into a discrete set of shifted and modulated versions of an elementary signal is reviewed and its relation to sampling of the sliding-window spectrum is shown. It is indicated how Gabor's expansion coefficients can be found as samples of the sliding-window spectrum, where the window function - which still has to be determined - is related to the elementary signal. Gabor's critical sampling as well as the case of oversampling by an Integer Factor are considered. The Zak transform is introduced and its intimate relationship to Gabor's signal expansion is demonstrated. It is shown how the Zak transform can be helpful in determining Gabor's expansion coefficients and how it can be used in finding window functions that correspond to a given elementary signal. An arrangement is described which is able to generate Gabor's expansion coefficients of a rastered, one-dimensional signal by coherent-optical means.
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oversampling in gabor s signal expansion by an Integer Factor
IEEE-SP International Symposium on Time-Frequency and Time-Scale Analysis, 1994Co-Authors: M J BastiaansAbstract:Gabor's (1946) expansion of a signal into a discrete set of shifted and modulated versions of an elementary signal is reviewed and its relation to sampling of the sliding-window spectrum is shown. It is indicated how Gabor's expansion coefficients can be found as samples of the sliding-window spectrum, where the window function, which still has to be determined, is related to the elementary signal. Gabor's critical sampling as well as the case of oversampling by an Integer Factor are considered. The Zak (1967) transform is introduced and its intimate relationship to Gabor's signal expansion is demonstrated. It is shown how the Zak transform can be helpful in determining Gabor's expansion coefficients and how it can be used in finding window functions that correspond to a given elementary signal. An arrangement is described which is able to generate Gabor's expansion coefficients of a rastered, one-dimensional signal by coherent-optical means. >
D Babic - One of the best experts on this subject based on the ideXlab platform.
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decimation by non Integer Factor in multistandard radio receivers
Signal Processing, 2005Co-Authors: D Babic, Markku RenforsAbstract:In many applications it is required to have a system for non-Integer sampling rate conversion (SRC), which supports any decimation Factor, and provides enough attenuation for aliasing and imaging signal components. A good example case is a software radio receiver, where the ratio of sampling rate just after A/D converter and symbol rate for a supported standard may be a ratio of two large mutually prime numbers. In a digital mobile receiver, it is very important to reduce the power consumption. The power consumption in context of SRC can be reduced by designing a system that has low rate of multiplication and addition operations.This paper introduces a novel non-Integer decimation method. The proposed structure is a combination of an FIR filter and a polynomial-based interpolation filter. For the special case based on a cascaded integrator-comb (CIC) filter and simple polynomial-based interpolation filter, the proposed combination has a very efficient implementation structure. The results shown in this paper indicate that the computational complexity and multiplication rate can be reduced compared to the earlier solutions.
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decimation by non Integer Factor in software radio receivers
Facta universitatis. Series electronics and energetics, 2003Co-Authors: D Babic, Markku RenforsAbstract:The sampling rate conversion is a critical functionality of the software radio receiver. Because the signals of different system standards have incommensurate symbol/sampling rates and a common Analog-to Digital Converter (ADC) is to be used for all supported standards, the decimation Factor may become very difficult non-Integer number. This paper gives overviews and comparisons of two efficient fractional decimator structures based on Cascaded Integrator-Comb (CIC) filters and low order polynomialbased interpolation filters.
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EUSIPCO - Programmable modified fractional comb decimation filter
2002Co-Authors: D Babic, Markku RenforsAbstract:In multistandard radio receivers, the hardware should be configurable or programmable for the reception of different types of signals having different symbol rates. The decimation by a non-Integer Factor becomes a critical functionality of the multistandard radio. The Cascaded Integrator-Comb (CIC) filters are commonly used for decimation by an Integer. By using polynomial interpolation filter between integrator and comb stages of CIC, and non-Integer delay in the feed-forward branch of the comb stage, we achieve improved attenuation for the aliasing frequency components, and we make possible to use this type of structure for decimation by a non-Integer Factor. We name this structure as a programmable fractional CIC filter structure. This paper presents an efficient fractional structure for flexible decimation in the multistandard radio receivers. This structure is based on the so-called modified comb filter using the programmable fractional CIC principle. The main advantages of the proposed structure are flexibility and programmability with increased attenuation for aliasing frequency components.
M C W Geilen - One of the best experts on this subject based on the ideXlab platform.
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gabor s signal expansion and the zak transform with oversampling by an Integer Factor
IEEE Transactions on Signal Processing, 1995Co-Authors: M J Bastiaans, M C W GeilenAbstract:Gabor's expansion of a signal into a discrete set of shifted and modulated versions of an elementary signal is reviewed and its relation to sampling of the sliding-window spectrum is shown. It is indicated how Gabor's expansion coefficients can be found as samples of the sliding-window spectrum, where the window function - which still has to be determined - is related to the elementary signal. Gabor's critical sampling as well as the case of oversampling by an Integer Factor are considered. The Zak transform is introduced and its intimate relationship to Gabor's signal expansion is demonstrated. It is shown how the Zak transform can be helpful in determining Gabor's expansion coefficients and how it can be used in finding window functions that correspond to a given elementary signal. An arrangement is described which is able to generate Gabor's expansion coefficients of a rastered, one-dimensional signal by coherent-optical means.
Amod Agashe - One of the best experts on this subject based on the ideXlab platform.
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Visibility and the Birch and Swinnerton-Dyer conjecture for analytic rank zero
arXiv: Number Theory, 2009Co-Authors: Amod AgasheAbstract:Let $E$ be an optimal elliptic curve over $\Q$ of conductor $N$ having analytic rank zero, i.e., such that the $L$-function $L_E(s)$ of $E$ does not vanish at $s=1$. Suppose there is another optimal elliptic curve over $\Q$ of the same conductor $N$ whose Mordell-Weil rank is greater than zero and whose associated newform is congruent to the newform associated to $E$ modulo an Integer $r$. The theory of visibility then shows that under certain additional hypotheses, $r$ divides the product of the order of the Shafarevich-Tate group of $E$ and the orders of the arithmetic component groups of $E$. We extract an explicit Integer Factor from the the Birch and Swinnerton-Dyer conjectural formula for the product mentioned above, and under some hypotheses similar to the ones made in the situation above, we show that $r$ divides this Integer Factor. This provides theoretical evidence for the second part of the Birch and Swinnerton-Dyer conjecture in the analytic rank zero case.
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Visibility and the Birch and Swinnerton–Dyer Conjecture for Analytic Rank One
International Mathematics Research Notices, 2009Co-Authors: Amod AgasheAbstract:Let E be an optimal elliptic curve over of conductor N having analytic rank one, i.e. such that the L-function L E (s) of E vanishes to order one at s = 1. Let K be a quadratic imaginary field in which all the primes dividing N split and such that the L-function of E over K vanishes to order one at s = 1. Suppose there is another optimal elliptic curve over of the same conductor N whose Mordell-Weil rank is greater than one and whose associated newform is congruent to the newform associated to E modulo an Integer r. The theory of visibility then shows that under certain additional hypotheses, r divides the product of the order of the Shafarevich-Tate group of E over K and the orders of the arithmetic component groups of E. We extract an explicit Integer Factor from the Birch and Swinnerton-Dyer conjectural formula for the product mentioned above, and under some hypotheses similar to the ones made in the situation above, we show that r divides this Integer Factor. This provides theoretical evidence for the second part of the Birch and Swinnerton-Dyer conjecture in the analytic rank one case.