Authors:
Carine Simon, Laboratoire systèmes de communication - UMLV - Champs sur Marne - 5, bvd Descartes - 77454 Marne la Vallée Cedex - FRANCE (France)
Philippe Loubaton, Laboratoire systèmes de communication - UMLV - Champs sur Marne - 5, bvd Descartes - 77454 Marne la Vallée Cedex - FRANCE (France)
Christophe Vignat, Laboratoire systèmes de communication - UMLV - Champs sur Marne - 5, bvd Descartes - 77454 Marne la Vallée Cedex - FRANCE (France)
Christian Jutten, LIS/TIRF - 44,avenue Félix Viallet - 38031 Grenoble Cedex - FRANCE (France)
Guy d'Urso, EDF/DER - 6, quai Watier - 78401 Chatou Cedex - FRANCE (France)
Page (NA) Paper number 1666
Abstract:
In this paper, we address the problem of the separation of convolutive
mixtures in the case where the non Gaussian source signals are not
necessarily filtered versions of i.i.d. sequences. In this context,
we show that the contrast functions, used in the linear process source
case, still allow to separate the sources by a deflation approach.
Some particular properties of higher order cumulants based contrast
functions are also given.
Authors:
T. Engin Tuncer, Middle East Technical Unv., EE. Dept., Ankara, Turkey (U.K.)
Page (NA) Paper number 1143
Abstract:
Recently a new time-domain method has been presented for deconvolution
[1]. This multidimensional method completely eliminates the problems
of the previous methods in one dimension and covers a reasonable part
of the solutions in multidimensions. In this paper, we present some
of the properties of this method. We will especially focus on the frequency
domain behaviour of the algorithm as well as the performance under
numerical errors and errors due to noise. In addition we will present
examples of the applications including deconvolution with a modified
NAS-RIF algorithm.
Authors:
James P Reilly, Communications Research Laboratory, McMaster University, 1280 Main St. W., Hamilton Ontario, CANADA L8S 4K1 (Canada)
Lino E Coria Mendoza, Communications Research Laboratory, McMaster University, 1280 Main St. W, Hamilton, Ontario, CANADA L8S 4K1 (Canada)
Page (NA) Paper number 2031
Abstract:
In this paper we extend the infomax technique [1] for blind signal
separation from the instantaneous mixing case to the convolutive mixing
case. Separation in the convolutive case requires an unmixing system
which uses present and past values of the observation vector, when
the mixing system is causal. Thus, in developing an infomax process,
both temporal and spatial dependence of the observations must be considered.
We propose a stochastic gradient based structure which accomplishes
this task. Performance of the proposed method is verified by subjective
listening tests and quantitative measurements.
Authors:
Dragan Obradovic,
Page (NA) Paper number 2286
Abstract:
Methods for blind source separation (BSS) from linear instantaneous
signal mixtures have drawn a significant attention due to their ability
to recover original independent non-Gaussian sources without analyzing
their temporal statistics. Hence, original voices or images (modulo
permutation and linear scaling) are extracted from their mixtures without
modeling the dynamics of the signals. The typical methods for performing
blind source separation are Linear Independent Component Analysis (ICA)
and the InfoMax method. Linear ICA directly penalizes a suitably chosen
measure of the statistical dependence between the extracted signals.
These measures are either obtained from the Information theoretic postulates
such as the mutual information or from the cumulant expansion of the
associated probability density functions. The InfoMax method is based
on the entropy maximization of the non-linear transformation of the
separated signals. This paper analyzes extensions of the instantaneous
blind source separation techniques to the case of linear dynamic signal
mixtures. Furthermore, the paper introduces a novel method based on
combining Time Delayed Decorrelation (TDD) with the minimization of
the cumulant cost function. TDD is used to obtain an acceptable initial
condition for the cumulant based cost function optimization in order
to reduce the numerical complexity of the latter method. This combined
approach is illustrated on two examples including a real life cocktail
party example. Keywords: higher order statistics, signal reconstruction
Authors:
Anisse Taleb,
Christian Jutten,
Page (NA) Paper number 1737
Abstract:
This paper discusses some theoritical results on underdetermined source
separation i.e. when the mixing matrix is degenerate, espcially when
there is more sources than observations. In this case, we show that
the sources can be restored up to an arbitrary additive random vector.
In the particular case of discrete sources, very relevant for digital
communications, we show that this vector is certain.
Authors:
James R Hopgood,
Peter J.W Rayner,
Page (NA) Paper number 1682
Abstract:
Separability of signal mixtures given only one mixture observation
is defined as the identification of the accuracy to which the signals
can be separated. The paper shows that when signals are separated using
the generalised Wiener filter, the degree of separability can be deduced
from the filter structure. To identify this structure, the processes
are represented on an arbitrary spectral domain, and a sufficient solution
to the Wiener filter is obtained. The filter is composed of a term
independent of the signal values, corresponding to regions in the spectral
domain where the desired signal components are not distorted by interfering
noise components, and a term dependent on the signal correlations,
corresponding to the region where components overlap. An example of
determining perfect separability of modulated random signals is given.
Authors:
Vicente Zarzoso,
Asoke K Nandi,
Page (NA) Paper number 1144
Abstract:
Blind source separation aims to extract a set of independent signals
from a set of observed linear mixtures. After whitening the sensor
output, the separation is achieved by estimating an orthogonal transformation,
which in the real-mixture two-source two-sensor case is entirely characterized
by a single rotation angle. This contribution studies an estimator
of such an angle. Even though it is derived from geometric notions
based on the scatter-plots of the signals involved, it is found, empirically,
to exhibit a performance clearly up to the mark of other methods based
on optimality criteria and, theoretically, to improve and generalize
one of such procedures. The simplicity of the suggested estimator results
in a straightforward adaptive version, which converges regardless of
the source distribution, for quite mild conditions, and whose asymptotic
analysis is easy to carry out. The applicability of the estimator in
a full separation system is also illustrated.
Authors:
Lahouari Ghouti,
Chi Hau Chen,
Page (NA) Paper number 5067
Abstract:
In ultrasonic nondestructive evaluation (NDE) of materials, pulse echo
measurements are masked by the characteristics of the measuring instruments,
the propagation paths taken by the ultrasonic pulses, and are corrupted
by addictive noise. Deconvolution operation seeks to undo these masking
effects and extract the defect impulse response which is essential
for identification. In this contribution, we show that the use of higher-order
statistics (HOS)-based deconvolution methods is more suitable to unravel
the aforementioned effects. Synthetic and real ultrasonic data obtained
from artificial defects is used to show the improved performance of
the proposed technique over conventional ones, based on second-order
statistics (SOS), commonly used in ultrasonic NDE.
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