Time filter

Source Type

Matawan, NJ, United States

Raj R.G.,US Radar
2012 IEEE Statistical Signal Processing Workshop, SSP 2012 | Year: 2012

We introduce a novel methodology for calculating discriminative codes for different classes of vectors with respect to the same dictionary. This is accomplished by introducing and quantifying the concept of mutual exclusivity between two classes of vectors (endowed possibly with different probabilistic structures) in a manner amenable to convex programming. We study theoretical properties of our mutual exclusivity operator and experimentally demonstrate its capability in generating effective discriminative codes that successfully incorporate both intra-class and inter-class characteristics. We conclude with a brief discussion of a generalization our mutual exclusivity operator to handle arbitrary number of classes, together with future directions emanating from this work. © 2012 IEEE. Source

Chen R.C.,US Radar
IEEE National Radar Conference - Proceedings | Year: 2010

Optimal waveforms for minimum mean square error range profile estimation are investigated. An idealized measurement and waveform adaptation process is developed that yields optimal scene and range specific waveforms. This process is idealized in that during each cycle of the process, a large number of dwells are required. As part of our method, a modified version of the Adaptive Pulse Compression (APC) estimation method is used to estimate the range profile after each dwell cycle. The proposed method is analogous to the APC method in that it yields a set of range specific optimal waveforms, while the APC method yields a set of range specific optimal pulse compression filters. In certain scenarios, the measurement and waveform adaptation process yields range profile estimates that are significantly better than those derived by the APC method alone. © 2010 IEEE. Source

Henke D.,University of Kansas | McCormick P.,University of Kansas | Blunt S.D.,University of Kansas | Higgins T.,US Radar
IEEE National Radar Conference - Proceedings | Year: 2015

The sensitivity impact of range straddling in the form of mismatch loss is well known. What is less appreciated, however, is the effect upon dynamic range, particularly for receive filtering that seeks to minimize range sidelobes. For FM-based waveforms, which are readily implementable in a high-power radar system, it is shown that least-squares (LS) mismatched filtering (MMF) realizes a penalty in sidelobe suppression when range straddling occurs. This degradation can be partially compensated through modification of the LS MMF implementation. Alternatively, adaptive pulse compression (APC), appropriately modified for application to FM waveforms, demonstrates robustness to both straddling and eclipsing effects. Simulated and experimentally measured results are provided to demonstrate the efficacy of these filtering approaches. © 2015 IEEE. Source

Raj R.G.,US Radar
IEEE National Radar Conference - Proceedings | Year: 2014

We apply our recently developed concept of mutual exclusivity [1] in the context of discriminative coding, to the problem of learning dictionary for representing signals drawn from N classes in a way that optimizes their discriminability. We first briefly review our mutual-exclusivity concept and then deploy it a simple discriminative dictionary learning algorithm that directly generalizes the well-known KSVD algorithm which is addressed for the traditional problem of signal coding. We demonstrate performance improvements over traditional KSVD based feature extraction schemes and conclude by describing avenues for future research. © 2014 IEEE. Source

Dorsey W.M.,US Radar | Dorsey W.M.,Virginia Polytechnic Institute and State University | Zaghloul A.I.,Virginia Polytechnic Institute and State University | Zaghloul A.I.,U.S. Army
IET Microwaves, Antennas and Propagation | Year: 2013

A dual-band element that operates with dual-circular polarisation in two separate industrial, scientific and medical bands is presented. The design that is based on concentric square slot/shorted-ring configuration is realisable in cost-effective printed circuit board technology making it attractive for low-cost personal communications devices. The antenna element provides a flexible topology that allows for convenient, independent control of the polarisation and impedance bandwidth of two distinct frequency bands with no fundamental limitation on the ratio between the high- and low-band frequency ranges. The topology of this element is presented, and the antenna concept is validated via simulated and measured results. © The Institution of Engineering and Technology 2013. Source

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