IEEE - Aerospace and Electronic Systems - May 2022 - Tutorial XV - 99

IEEE AES Tutorials
attention from the image processing scientific community.
In this paper, we consider the specific problem of anomalous
change detection (ACD) in hyperspectral images and
discuss how images taken at two different times can be
processed to detect changes caused by insertion, deletion,
or displacement of small objects in the monitored scene.
We introduce the ACD problem using an approach based
on the statistical decision theory and we derive a common
framework including different ACD approaches. Far from
being inclusive of all the methods proposed in the literature,
this tutorial overview places emphasis on techniques
based on the multivariate Gaussian model that allows a
formal presentation of the ACD problem and the rigorous
derivation of the possible solutions in a way that is both
mathematically more tractable and easier to interpret. The
unification of different approaches under a single rigorous
statistical scheme provides both a tutorial overview of
ACD techniques, and a useful instrument for researchers
already familiar with the ACD problem. Dedicated preprocessing
methods aimed at improving the robustness of
the ACD process are also discussed. Real data are
exploited to test and compare the presented methods,
highlighting advantages and drawbacks of each approach.
The tutorial aspect of the paper has suggested the use of a
freely available data set. This should hopefully motivate the
interested reader to experiment with the processing methods
and performance evaluation chain presented herein.
ARE PLLS DEAD? A TUTORIAL ON KALMAN FILTER-BASED
TECHNIQUES FOR DIGITAL CARRIER SYNCHRONIZATION
JORDI VILA-VALLS
Centre Tecnologic de Telecomunicacions de Catalunya
(CTTC/ CERCA)
Barcelona, Spain
PAU CLOSAS
Northeastern University
Boston, MA, USA
MONICA NAVARRO
CARLES FERNANDEZ-PRADES
Centre Tecnologic de Telecomunicacions de Catalunya
(CTTC/ CERCA)
Barcelona, Spain
Carrier synchronization is a fundamental stage in the
receiver side of any communication or positioning system.
Traditional carrier phase tracking techniques are based on
well-known phase-locked loop (PLL) closed-loop architectures,
which are still the methods of choice in modern
receivers. Those techniques are well understood, easy to
tune, and performwell under benign propagation conditions,
but their applicability is seriously compromised in harsh
propagation environments, where the signal may be affected
by high dynamics, shadowing, strong fadings, multipath
effects, or ionospheric scintillation. From an optimal
MAY 2022
filtering standpoint, the Kalman filter (KF) is clearly a powerful
alternative, but the synchronization community seems
still reluctant to exploit all the potential it has to offer. The
purpose of this article is twofold: i) to review the basics and
state of the art on both PLL and KF-based tracking techniques
and ii) to present and justify the reasoning behind the
systematic use of KF-based tracking approaches instead of
the well established PLL-based architectures from both theoretical
and practical points of view. To support the discussion,
two specific scenarios of interest to the aerospace
community are numerically evaluated: robust carrier tracking
of global navigation satellite systems' signals and synchronization
in a deep space communications system.
WEATHER RADAR: OPERATION AND PHENOMENOLOGY
JENNY L. REED
AARON D. LANTERMAN
JOHN M. TROSTEL
Georgia Tech Research Institute
Smyrna, GA, USA
Radar is an indispensable technology in areas of defense,
air traffic control (ATC), and weather surveillance. The
usual goal of defense and air traffic control radars is to
detect and track individual
targets; in contrast, the " target " of weather radars may
stretch hundreds of kilometers. The meteorology, defense,
and ATC communities typically publish research in different
venues, and each community has a vernacular and
characteristic ways of approaching problems. The goals of
this article are twofold. Its primary goal is to summarize
typical weather radar systems and define associated jargon
in terms more familiar to other radar communities. The
second goal is to provide a detailed discussion
of the physical scattering phenomenology exploited specifically
in radar meteorology. Furthermore, while there
are a number of operational weather radars, we focus
throughout much of this article on the most common
weather radar, Weather Surveillance Radar 1988 Doppler
(WSR-88D), as a canonical example, because much of the
current research and phenomenological analysis are based
on its operational parameters.
TUTORIAL XII
PASSIVE RADAR TUTORIAL
HEINER KUSCHEL
DIEGO CRISTALLINI
Fraunhofer, Germany
KARL ERIK OLSEN
Norwegian Defence Research Establishment
Norway
Passive Radar signifying the localization of a target by radar
measurements without using own controlled emissions has
IEEE A&E SYSTEMS MAGAZINE
99
IEEE - Aerospace and Electronic Systems - May 2022 - Tutorial XV

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