IEEE - Aerospace and Electronic Systems - March 2021 - 85

IEEE AES Tutorials

considerations. The central section of the paper describes
the major algorithmic steps required to form an IFSAR
terrain map. Finally, variations of IFSAR for mapping terrain elevation or reflectivity changes are briefly described.
A web site at users.ece.gatech.edu/»mrichard/AESS IFSAR.htm provides access to color versions of many of the
IFSAR images included in this paper.

LORAN DATA MODULATION: A PRIMER
SHERMAN C. LO, Member, IEEE
Stanford University
BENJAMIN B. PETERSON, Senior Member, IEEE
Peterson Integrated Geopositioning
PER K. ENGE, Fellow, IEEE
Stanford University
Loran has provided navigation service since 1958. Though
not originally designed with data broadcast capabilities,
Loran's versatility has enabled data to be broadcast with
great benefits.
Research in the last two decades has resulted in a tremendous increase in the data capacity of Loran thereby increasing its utility. Currently, a modernized Loran is being
evaluated for its capability to backup GPS and data modulation is an integral part of this Loran design. An overview
and analysis of Loran modulation techniques is provided.

a function of the issues cited above. These formulations
provide analytical bases to guide system trade-off decisions. The organization of this paper is as follows. We
begin with a short overview of HRR and RDI and then
explore a number of ways to process the associated target
templates that range from an ideal, theoretical approach to
an approach that would be more feasible to implement
within current-day radars. We first develop analytic template-based methodologies for constructing confusion
matrix entries for nonscintillating targets for both coherent
and noncoherent processing assumptions. The confusion
matrix entries in these cases are conditional probabilities
obtained from a simple rule: find the probability that among
m (in general, correlated) random variables, each associated with a possible target, that any one is the largest. For
the noncoherent case, the successful application of this rule
requires the target template values to explicitly include the
effects of thermal noise (noise-adjusted templates). We
conclude by showing how to calculate theoretically optimum results (e.g., using maximum likelihood techniques)
for noncoherent processing of targets that exhibit uncorrelated Swerling 1 scintillation in all resolution bins as a
function of the SNR. This approach allows us to include
overall target intensity (e.g., total radar cross section
(RCS)) as a further factor in the target decision process.

TUTORIAL V
TEMPLATE-BASED TARGET IDENTIFICATION AND
CONFUSION MATRICES

Published as Part 2 of IEEE Aerospace & Electronic
Systems Magazine

KENT HASPERT, Member, IEEE
JAMES HEAGY
ROGER SULLIVAN, Member, IEEE
Institute for Defense Analyses

Volume Twenty-Five Number Seven-July 2010.

One-dimensional high-range-resolution (HRR) and twodimensional range-Doppler-imaging (RDI) radar represent
possible sensor technologies where template-based techniques can be applied to perform combat identification (CID).
The majority of the research reported in these areas consists
of empirical studies. This article provides a theoretical basis
for understanding some of the fundamental trade-offs associated with these CID techniques, such as the following.
1) What are the relative advantages of RDI over HRR
radar or of finer versus coarser resolution in the
HRR process?
2) What is the relative advantage of coherent over
noncoherent processing?
3) How do target correlations, signal-to-noise ratio
(SNR), and target scintillation affect the ability to
identify targets?
Because confusion matrices are often used to characterize
the performance of CID systems, we provide analytical
methods for calculating the entries in confusion matrices as
MARCH 2021

A TUTORIAL OVERVIEW OF ANOMALY DETECTION IN
HYPERSPECTRAL IMAGES
STEFANIA MATTEOLI, Student Member, IEEE
MARCO DIANI, Member, IEEE
GIOVANNI CORSINI, Member, IEEE
University of Pisa
In this paper, a tutorial overview on anomaly detection for
hyperspectral electro-optical systems is presented. This
tutorial is focused on those techniques that aim to detect
small man-made anomalies typically found in defense and
surveillance applications. Since a variety of methods have
been proposed for detecting such targets, this tutorial places emphasis on the techniques that are either mathematically more tractable or easier to interpret physically.
These methods are not only more suitable for a tutorial
publication, but also an essential to a study of anomaly
detection. Previous surveys on this subject have focused
mainly on anomaly detectors developed in a statistical
framework and have been based on well-known background statistical models. However, the most recent
research trends seem to move away from the statistical

IEEE A&E SYSTEMS MAGAZINE

IEEE - Aerospace and Electronic Systems - March 2021

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