Authors:
David C. Munson Jr.,
Orhan Arikan,
Page (NA) Paper number 3025
Abstract:
This paper considers the problem of interpolating a signal from one
uniformly-spaced grid to another, where the grid spacings may be related
by an arbitrary, irrational factor. Noting that interpolation is the
digital equivalent of magnification, we begin by reviewing optical
systems for magnification and "computation" of the chirp Fourier transform.
This route suggests several analog schemes for magnification, which
can be discretized to produce algorithms for interpolation. We then
derive one of these algorithms from first principles, using a digital-signal-processing
perspective. The result is an important, but forgotten, algorithm for
interpolation first suggested as an application of the chirp-z transform
by Rabiner, Schafer, and Rader. Unlike the earlier derivation, our
approach is direct -- we do not make use of Bluestein's trick of completing
the square. In addition, our approach identifies parameters under user
control that can be optimized for best performance.
Authors:
Michael Papazoglou, Duke University (U.K.)
Jeffrey L Krolik, Duke University (U.K.)
Page (NA) Paper number 3003
Abstract:
In previous work, a matched-field estimate of aircraft altitude which
uses multiple over-the-horizon radar dwells was presented. This approach
exploited the altitude dependent structure of the micro-multipath rays
which result from reflections local to the aircraft. While it was shown
that the multi-dwell matched-field estimate is able to accurately estimate
altitude while using typical radar parameters, the estimate was derived
assuming that the aircraft altitude is constant for the duration of
the track. In this paper, a matched-field method for jointly estimating
altitude and altitude rate is presented which extends the micro-multipath
model to include effects of constant altitude rate on the micro-multipath
Doppler frequencies. Simulation results illustrate that altitude and
altitude rate can be jointly estimated while achieving an altitude
estimation accuracy of +/-2500 feet using 10 radar dwells.
Authors:
M. Porter,
P. Roux,
H. Song,
W. Kuperman,
Page (NA) Paper number 3026
Abstract:
There has been a great deal of work in ocean science over the last
10 years in using acoustic channel models in the signal processing.
The goal has been to compensate for the "barbershop" effect in which
a SONAR system confuses the true source with its reflections in the
acoustic mirrors formed by the ocean surface and bottom. Separately,
in medicine, hyperthermia acoustic beams are trained on tumors with
the goal of reversing their growth. Our interest is the question of
what (if any) lessons from the SONAR experience can be applied to hyperthermia.
Authors:
Peter Gerstoft,
Donald F. Gingras,
Page (NA) Paper number 3027
Abstract:
Modern signal and array processing methods now incorporate the physics
of wave propagation as an integral part of the processing. Matched
field processing (MFP) refers to signal and array processing techniques
in which, rather than a plane wave arrival model, complex-valued (amplitude
and phase) field predictions for propagating signals are used. Matched
field processing has been successfully applied in ocean acoustics and
electromagnetics. In this paper, source localization performance via
MFP is examined in the electromagnetics domain. Specifically, the impact
of uncertainty in the a priori knowledge of the underlying physical
parameters, atmospheric refractivity vs height, on source localization
performance is examined.
Authors:
Paul Runkle, Department of Electrical and Computer Engineering, Duke University (U.K.)
Lawrence Carin, Department of Electrical and Computer Engineering, Duke University (U.K.)
Page (NA) Paper number 3001
Abstract:
A wave-based matching-pursuits algorithm is used to parse multi-aspect
time-domain backscattering data into its underlying wavefront-resonance
constituents, or features. Consequently, the N multi-aspect waveforms
under test are mapped into N feature vectors. Target identification
is effected by fusing these N vectors in a maximum-likelihood sense,
which we show, under reasonable assumptions, can be implemented via
a hidden Markov model (HMM). Algorithm performance is assessed by considering
measured acoustic scattering data from five similar submerged elastic
targets.
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