1,720,960 research outputs found
Adaptive System Identification with Tap-Assignment in Oversampled and Critically Sampled Subbands
No full textAdaptation of the tap profile in subband adaptive system identification problems can further enhance the efficient use of computational resources if implemented on a DSP with an otherwise too tight benchmark performance. Here, we derive a generalisation of previous work to extend tap-assignment algorithms to a new class of oversampled filter banks with non-uniform bandwidths and different subsampling rations. We compare efficiency and adaptation results for this approach to the critically sampled case and a fullband identification with same complexity
Design and Efficient Implementation of Oversampled GDFT Filter Banks for Subband Adaptive Filtering
No full textThis paper introduces a polyphase implementation and design of an oversampled K-channel generalized DFT (GDFT) filter bank, which can be employed for subband adaptive filtering, and therefore is required to have a low aliasing level in the subband signals. A polyphase structure is derived which can be factorized into a real valued polyphase network and a GDFT modulation. For the latter, an FFT realization may be used, yielding a highly efficient polyphase implementation for arbitrary integer decimation ratios N <= K. We also present an analysis underlining the efficiency of complex valued subband processing. The design of the filter bank is completely based on the prototype filter and solved using a fast converging iterative least squares method, for which we give examples. The design specifications closely correspond with performance limits of subband adaptive filtering, which are under-pinned by simulation results
Polyphase Analysis of Subband Adaptive Filters
No full textIn this paper, we derive a polyphase analysis to determine the optimum filters in a subband adaptive filter (SAF) system. The structure of this optimum solution deviates from the standard SAF approach and presents its best possible solution only as an approximation. Besides this new insight into SAF error sources, the discussed analysis allows to calculate the optimum subband responses and the standard SAF approximation. Examples demonstrating the validity of our analysis and its use for determining SAF errors are presented
Interactive Teaching of Adaptive Signal Processing
No full textOver the last 30 years adaptive digital signal processing has progressed from being a strictly graduate level advanced class in signal processing theory to a topic that is part of the core curriculum for many undergraduate signal processing classes. The key reason is the continued advance of communications technology, with its need for echo control and equalisation, and the widespread use of adaptive filters in audio, biomedical, and control applications. In this paper we will review the basic theory and applications of adaptive signal processing and also present information on the current multimedia teaching methods on an adaptive signal processing 24 hour module course. In particular we will present some recent world wide web JAVA programmes that were developed for teaching and self-study. We also provide information on how to download and run the JAVA applet
Design of Near Perfect Reconstruction Oversampled Filter Banks for Subband Adaptive Filters
Full text linkIn this brief, a design algorithm for real-valued and complex-valued oversampled filter banks which yield a low level of inband alias and enable simple subband adaptiv structures is presented. The filter banks are either based on complex modulation of a real-valued low-pass prototype or on the direct or modulated setups of real-valued filter banks. If real-valued filter banks are required, then the different channels will have different subsampling ratios so that the bandpass sampling theorem is not violated. This brief also presents design examples of real-valued and complex-valued filter banks
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
On Implementation and Design of Filter Banks for Subband Adaptive Systems
No full textThis paper introduces a polyphase implementation and design of an oversampled K-channel generalized DFT (GDFT) filter bank, which can be employed for subband adaptive filtering, and therefore is required to have a low aliasing level in the subband signals. A polyphase structure is derived which can be factorized into a real valued polyphase network and a GDFT modulation. For the latter, an FFT realization may be used, yielding a highly efficient polyphase implementation for arbitrary integer decimation ratios N <= K. We also present an analysis underlining the efficiency of complex valued subband processing. The design of the filter bank is completely based on the prototype filter and solved using a fast converging iterative least squares method, for which we give examples. The design specifications closely correspond with performance limits of subband adaptive filtering, which are under-pinned by simulation results
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