Showing papers on "Reassignment method published in 1997"
TL;DR: A new fast algorithm is introduced which allows the recursive evaluation of classical spectrogram and spectrograms modified by the reassignment method to be extended to CTFDs and can be used to compute recursively reassigned smoothed pseudo-Wigner—Ville distributions.
27 citations
TL;DR: The impact of the reassigned time-frequency representation on the ability to reliably estimate instantaneous frequency for a given seismic signal is studied.
Abstract: This paper explores the method of reassignment for extracting instantaneous frequency attributes from seismic data. The reassignment method was rst applied to the spectrogram by Kodera, Gendrin and de Villedary [5] and later generalized to any bilinear time-frequency or time-scale representation by Auger and Flandrin [1]. Key to the method is a nonlinear convolution where the value of the convolution is not placed at the center of the convolution kernel but rather reassigned to the center of mass of the function within the kernel. The resulting reassigned representation yields signi cantly improved component localization. In this paper we will study the impact of the reassigned time-frequency representation on our ability to reliably estimate instantaneous frequency for a given seismic signal.
14 citations
01 Jan 1997
TL;DR: The proposed solution is based upon a new extension of the reassignment method which allows us to extract the signal component with the help of an unsupervised clustering algorithm.
Abstract: We are dealing with the problem of the partitioning of the timefrequency plane to obtain a simplified description of the signal from which it is possible to extract and reconstruct each of its components. The proposed solution is based upon a new extension of the reassignment method which allows us to extract the signal component with the help of an unsupervised clustering algorithm. The original contribution lies in the way we extract the information used to build the time-frequency partition. In order to achieve this, we do not use the time-frequency distribution itself, but its reassignment vector field, so that we are considering the notion of signal component from a new perspective.
3 citations
TL;DR: In this article, three methods to convert length-frequency data from Total to Fork length were compared and two teleost species, panga Pterogymnus laniarius (with a forked tail) and lesser gurnard Chelidonichthys queketti (with an emarginate tail) were constructed from observed total and fork length measurements to determine the accuracy of the different conversion methods.
2 citations
01 Jan 1997
TL;DR: This work introduces a new fast algorithm which allows the recursive evaluation of classical spectrograms and spectrogram modified by the reassignment method and shows that rectangular, half-sine, Hamming, Hanning and Blackman functions can be used as running 'short-time' windows.
Abstract: Cohen's class time-frequency distributions (CTFDs) have significant potential for the analysis of non-stationary signals, even if the poor readability of their representations makes visual interpretations difficult. To concentrate signal components, Auger and Flandrin recently generalized the reassignment method (first applied to the spectrogram in the 1970s) to any bilinear representations. Unfortunately, this process is computationally expensive. In order to reduce computation time and to improve representations readability, we first introduce a new fast algorithm which allows the recursive evaluation of classical spectrograms and spectrograms modified by the reassignment method. In a second step, we show that rectangular, half-sine, Hamming, Hanning and Blackman functions can be used as running 'short-time' windows. Then the previous algorithm is extended to CTFDs. We show that the windows mentioned above can also be used to compute recursively reassigned smoothed pseudo-Wigner-Ville distributions. Finally, we show that the constraints on candidate windows are not very restrictive: any function (assumed periodic) can be used in practice as long as it admits a 'short enough' Fourier series decomposition. © 1997 Elsevier Science B.V.