Results 251 to 260 of about 4,499,288 (288)

Bilinear time-frequency distributions

1994
One of the main features of wavelet and Gabor theories is that they aim at decomposing signals into elementary ones localized to a certain extent in the time-frequency plane. One way of making this notion of localization more precise is to use time-frequency distributions.
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Cross Hilbert time-frequency distributions

SPIE Proceedings, 1998
It is mathematically convenient to consider both positive nd negative frequencies in signal representation. This idea is critically important to time-frequency analysis. Usually, however one is presented with real signals. It is also well known that the analytic signal is formed using the Hilbert transform.
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Wavelet windowed time-frequency distribution decompositions

SPIE Proceedings, 1997
This paper outlines means of combining and reconciling concepts associated with Cohen's class of distributions and with the wavelet transform. Both have their assets and their liabilities. Previous work has shown that one can decompose any time-frequency distribution (TFD) in Cohen's class into a weighted sum of spectrograms.
William J. Williams, Tzuhsien Sang, Jeffrey C. O Neill, Eugene J. Zalubas   +3 more
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On generalized-marginal time-frequency distributions

IEEE Transactions on Signal Processing, 1996
We introduce a family of time-frequency (TF) distributions with generalized marginals, i.e., beyond the time-domain and the frequency-domain marginals, in the sense that the projections of a TF distribution along one or more angles are equal to the magnitude squared of the fractional Fourier transforms of the signal.
Xiang-gen Xia, Y. Owechko, B.H. Soffer, R.M. Matic   +3 more
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Instantaneous frequency and time-frequency distributions

1995 International Conference on Acoustics, Speech, and Signal Processing, 2002
It is generally stated that the conditional mean frequency of a time-frequency distribution (TFD) should equal the instantaneous frequency of the signal. The commonly accepted definition of instantaneous frequency as the derivative of the phase of the analytic signal sometimes leads to curious results.
B. Tacer, P.J. Loughlin
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Local stationarity and time-frequency distributions

SPIE Proceedings, 2006
We use time-frequency distributions to define local stationarity of a random process. We argue that local stationarity is achieved when the Wigner spectrum is approximately factorable. We show that when that is the case the autocorrelation function is the one considered by Silverman in 1957. Other time-frequency representations are also considered.
GALLEANI, Lorenzo, COHEN L, SUTER B.
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Fast implementation of time-frequency distributions

[1992] Proceedings of the IEEE-SP International Symposium on Time-Frequency and Time-Scale Analysis, 2003
Cohen's class of bilinear time-frequency energy distributions (TFDs) offer improved resolution over linear time-frequency representations (TFRs). Several problems with TFDs persist. Many TFDs are costly to evaluate, nonrepresentational, and not associated with low-cost signal synthesis algorithms.
G.S. Cunningham, W.J. Williams
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Positive Time-Frequency Distributions via Quadratic Programming

Multidimensional Systems and Signal Processing, 1998
As is known, the Fourier Transform approach does not provide a good solution for nonstationary stochastic signals. A possible approach to such cases is provided by the so-called time-frequency analysis. There exist many ways to achieve it. One of them consists of a bilinear time-frequency representation, which needs an explicit description of a kernel ...
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Spectrogram decompositions of time-frequency distributions

Proceedings of the Sixth International Symposium on Signal Processing and its Applications (Cat.No.01EX467), 2002
This paper outlines means of combining spectrograms formed using specially designed windows. Previous work has shown that one can decompose any time-frequency distribution (TFD) in Cohen's class into a weighted sum of spectrograms. This is accomplished by decomposing the kernel of the distribution in terms of an orthogonal set of analysis windows.
W.J. Williams, S. Aviyente
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Kernel decomposition of time-frequency distributions

IEEE Transactions on Signal Processing, 1994
Bilinear time-frequency distributions (TFDs) offer improved time-frequency resolution over linear representations, but suffer from difficult interpretation, higher implementation cost, and the lack of associated low-cost signal synthesis algorithms. In the paper, the authors introduce some new tools for the interpretation and quantitative comparison of
G.S. Cunningham, W.J. Williams
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