Authors:
Ranveig Nygaard,
John Haakon Husøy,
Dag Haugland,
Sven Ole Aase,
Page (NA) Paper number 1269
Abstract:
In this paper we present a signal compression scheme based on coding
linear segments approximating the signal. Although the approach is
useful for many types of signals, we focus in this paper on compression
of ElectroCardioGram (ECG) signals. ECG signal compression has traditionally
been tackled by heuristic approaches. However, it has recently been
demonstrated that exact optimization algorithms outclass these heuristic
approaches by a wide margin with respect to reconstruction error. The
exact optimization algorithm extracts signal samples from the original
signal by formulating the sample selection problem as a graph theory
problem. Thus known optimization theory can be applied in order to
yield optimal compression. This paper generalizes the exact optimization
scheme by removing the interpolation restriction when applying piecewise
linear approximation. This guarantees a lower reconstruction error
with respect to the number of extracted signal samples. The method
shows superior performance compared to traditional ECG compression
methods.
Authors:
Jakob Ängeby,
Mats Viberg,
Tony Gustafsson,
Page (NA) Paper number 1616
Abstract:
A novel approach for signal parameter estimation, named the Non-Linear
Instantaneous Least Squares (NILS) estimator, is proposed and a high
SNR statistical analysis of the estimates is presented. The algorithm
is generally applicable to deterministic signal in noise models. However,
it is of particular interest in applications where the ``conventional''
non-linear least squares criterion suffers from numerous local minima.
The key idea here is to apply a sliding window to estimate the instantaneous
amplitude, which is then used in a separable least squares criterion-function.
Hereby the radius of attraction of the global minimum is under the
control of the user, which makes the NILS approach advantegous to use
in practical applications.
Authors:
Kutluyil Dogançay, Inst. of Info. Sciences & Technology, Massey University, Palmerston North, New Zealand (New Zealand)
Vikram Krishnamurthy, Dept. of Electrical & Electronic Engineering, The University of Melbourne, Parkville, Australia (Australia)
Page (NA) Paper number 1354
Abstract:
Estimation of the state levels of a discrete-time, finite-state Markov
chain hidden in coloured Gaussian noise and subjected to unknown nonlinear
distortion is considered. If the nonlinear distortion has almost linear
behaviour for small values near zero or for large values, extreme value
theory can be applied to the level estimation problem, resulting in
simple estimation algorithms. The extreme value-based level estimator
is computationally inexpensive and has potential applications in data
measurement systems where inaccuracies are introduced by dead zones
or saturation in sensor characteristics. The effectiveness of the new
level estimator is demonstrated by way of computer simulations.
Authors:
Naresh Sharma,
Edward Ott,
Page (NA) Paper number 1089
Abstract:
Over the past several years, there have been various proposals for
communication with chaotic signals. But the issue of compensating the
distortions introduced by the physical channel like noise, time varying
fading and multi-path has not been fully addressed. In this paper,
we first describe a noise reduction method for chaotic signals corrupted
by an additive noise. The method uses the phenomenon of chaos synchronization
to approximate the maximum likelihood (ML) decoder for the AWGN channel.
Further we use the synchronizing receiver to nullify slowly time varying
fading and multi-path. We find the region of operation for such a receiver
and show how the time varying parameters characterizing such channels
can be tracked at the receiver.
Authors:
Zhiwen Zhu, Communications Research Laboratory, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (Canada)
Henry Leung, Surface Radar Section, Defence Research Establishment Ottawa, Ottawa, Ontario, Canada K1A 0Z4 (Canada)
Page (NA) Paper number 1318
Abstract:
The paper considers the adaptive identification of bilinear systems
using the equation-error approach. An improved least squares (ILS)
objective function is presented to reduce the bias of coefficient estimation
in the case of large measurement noise when the standard least squares
(LS) technique is used. An adaptive algorithm based on the ILS criterion
is proposed for the identification of the bilinear system. Numerical
simulations are given to demonstrate the effectiveness of the adaptive
ILS algorithm. Compared with the least mean squares (LMS) technique,
the proposed algorithm has superior identification performance.
Authors:
Patrick Celka,
Neil J Bershad,
Jean-Marc Vesin,
Page (NA) Paper number 1378
Abstract:
This paper present analytical, numerical and experimental results for
a stochastic gradient adaptive scheme which identifies a polynomial-type
nonlinear system with memory for noisy output observations. The analysis
includes the computation of the stationary points, the mean square
error surface, and the mean behavior of the algorithm for Gaussian
data. Monte Carlo simulations confirm the theoretical predictions which
show a small sensitivity to the observation noise.
Authors:
Hans-Peter Bernhard,
Georges A Darbellay,
Page (NA) Paper number 1945
Abstract:
Nonlinear signal processing is now well established both in theory
and applications. Nevertheless, very few tools are available for the
analysis of nonlinear systems. We introduce the mutual information
function (MIF) as a nonlinear correlation function and describe the
practicalities of estimating it from data. Even if an estimator is
consistent, it is of great interest to check what the bias and variance
are with a finite sample. We discuss these questions, as well as the
computational efficiency, for two estimators. Both algorithms are of
the complexity Nlog_2N, where N is the sample length, but they use
different methods to find the histogram for the estimation of the mutual
information. An efficient implementation makes it possible to apply
the algorithm on real time signal processing problems where the linear
correlation analysis breaks down. Current applications are: mobile
radio channels, load curve forecasting, speech processing, nonlinear
systems theory.
Authors:
Mahmut Ciftci,
Douglas B Williams,
Page (NA) Paper number 1967
Abstract:
In recent years, a variety of communications systems based on chaos
and nonlinear dynamics have been proposed. However, most of these algorithms
fail to work under realistic channel conditions. This paper presents
a channel equalization scheme for chaotic communication systems based
on a family of archetypal chaotic maps. The symbolic-dynamic representation
of these maps is exploited to allow a straightforward and efficient
implementation. Equalizer filter coefficients are updated using appropriately
modified versions of decision-directed and decision-feedback equalization
algorithms with adaptation based on the NLMS algorithm.
Authors:
Anders E. Nordsjö,
Lars H. Zetterberg,
Page (NA) Paper number 5061
Abstract:
The tracking problem in identification of certain classes of time-varying
nonlinear systems is addressed. In particular, a Hammerstein type system
which consists of a nonlinear part, given on a state space description,
followed by a time-varying linear part is considered. A Recursive Prediction
Error Method, RPEM combined with a method for on-line adjustment of
the forgetting factor is proposed. This algorithm does not require
estimation of the statistics of the noise and the dynamics of the true
system. It is shown how the proposed scheme can be used for identification
of certain nonlinear time varying acoustic echo paths. Thus, the suggested
algorithm is applicable to for instance, conference telephony and mobile
telephone handsfree.
Authors:
Byung-Jae Kwak,
Andrew E Yagle,
Joel A Levitt,
Page (NA) Paper number 2184
Abstract:
We present a finite-state memory model for parametric system identification
of the lip seal friction process in a hydraulic actuator. The performance
of the finite state memory model is compared to two Hammerstein type
models using experimental results.
Authors:
Costa Jean-Pierre,
Pronzato Luc,
Thierry Eric,
Page (NA) Paper number 1941
Abstract:
Prediction by kringing does not rely on any specific model structure,
and is thus much more flexible than approaches based on parametric
behavioural models. Since accurate predictions are obtained for extremely
short training sequences, it generally performs better than prediction
methods using parametric models. Application to nonlinear system inversion
is considered.
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