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Articles 1 - 8 of 8
Full-Text Articles in Electrical and Computer Engineering
Coupling Efficiencies For General Target Illumination Ladar Systems Incorporating Single Mode Optical Fiber Receivers, Christopher Brewer, Bradley Duncan, Kenneth Barnard, Edward Watson
Coupling Efficiencies For General Target Illumination Ladar Systems Incorporating Single Mode Optical Fiber Receivers, Christopher Brewer, Bradley Duncan, Kenneth Barnard, Edward Watson
Bradley D. Duncan
A rigorous method for modeling received power coupling efficiency (ηF/R) and transmitted power coupling efficiency (ηF/T) in a general-target-illumination ladar system is presented. For our analysis we concentrate on incorporating a single-mode optical fiber into the ladar return signal path. By developing expressions for both ηF/R and ηF/T for a simple, diffuse target, our model allows for varying range, beam size on target, target diameter, and coupling optics. Through numerical analysis ηF/R is shown to increase as the range to target increases and decrease as target diameter increases, and ηF/T is shown to decrease with target range. A baseline signal-to-noise …
Space-Bandwidth Product Enhancement Of A Monostatic, Multi-Aperture Infrared Image Upconversion Ladar Receiver Incorporating Periodically Polled Linbo3, Christopher Brewer, Bradley Duncan, Phillip Maciejewski, Sean Kirkpatrick, Edward Watson
Space-Bandwidth Product Enhancement Of A Monostatic, Multi-Aperture Infrared Image Upconversion Ladar Receiver Incorporating Periodically Polled Linbo3, Christopher Brewer, Bradley Duncan, Phillip Maciejewski, Sean Kirkpatrick, Edward Watson
Bradley D. Duncan
We investigate the space-bandwidth product of a ladar system incorporating an upconversion receiver. After illuminating a target with an eye-safe beam, we direct the return into a piece of periodically poled LiNbO3 where it is upconverted into the visible spectrum and detected with a CCD camera. The theoretical and experimental transfer functions are then found. We show that the angular acceptance of the upconversion process severely limits the receiver field of regard for macroscopic coupling optics. This limitation is overcome with a pair of microlens arrays, and a 43% increase in the system’s measured space-bandwidth product is demonstrated.
Fibre-Optic Network Architectures For On-Board Digital Avionics Signal Distribution, Mohammad Alam, Mohammed Atiquzzaman, Bradley Duncan, Hung Nguyen, Richard Kunath
Fibre-Optic Network Architectures For On-Board Digital Avionics Signal Distribution, Mohammad Alam, Mohammed Atiquzzaman, Bradley Duncan, Hung Nguyen, Richard Kunath
Bradley D. Duncan
Continued progress in both civil and military radio-frequency (RF) digital avionics applications is overstressing the capabilities and reliability of existing RF communication networks based on coaxial cables on board modern aircrafts. Future avionics systems will require high-bandwidth on-board communication links that are lightweight, immune to electromagnetic interference, and highly reliable. Fibre-optic networks can meet all these challenges in a cost-effective manner. Recently, on-board fibre-optic communication systems, where a fibre-optic network acts like a local area network (LAN) for digital data communications, have become a topic of extensive research and development. However, modern digital avionics systems require a system capable of …
Scene-Based Nonuniformity Correction With Video Sequences And Registration, Russell Hardie, Majeed Hayat, Ernest Armstrong, Brian Yasuda
Scene-Based Nonuniformity Correction With Video Sequences And Registration, Russell Hardie, Majeed Hayat, Ernest Armstrong, Brian Yasuda
Russell C. Hardie
We describe a new, to our knowledge, scene-based nonuniformity correction algorithm for array detectors. The algorithm relies on the ability to register a sequence of observed frames in the presence of the fixed-pattern noise caused by pixel-to-pixel nonuniformity. In low-to-moderate levels of nonuniformity, sufficiently accurate registration may be possible with standard scene-based registration techniques. If the registration is accurate, and motion exists between the frames, then groups of independent detectors can be identified that observe the same irradiance ~or true scene value!. These detector outputs are averaged to generate estimates of the true scene values. With these scene estimates, and …
Improved Optimization Of Soft Partition Weighted Sum Filters And Their Application To Image Restoration, Yong Lin, Russell Hardie, Qin Sheng, Kenneth Barner
Improved Optimization Of Soft Partition Weighted Sum Filters And Their Application To Image Restoration, Yong Lin, Russell Hardie, Qin Sheng, Kenneth Barner
Russell C. Hardie
Soft-partition-weighted-sum (Soft-PWS) filters are a class of spatially adaptive moving-window filters for signal and image restoration. Their performance is shown to be promising. However, optimization of the Soft-PWS filters has received only limited attention. Earlier work focused on a stochastic-gradient method that is computationally prohibitive in many applications. We describe a novel radial basis function interpretation of the Soft-PWS filters and present an efficient optimization procedure. We apply the filters to the problem of noise reduction. The experimental results show that the Soft-PWS filter outperforms the standard partition-weighted-sum filter and the Wiener filter.
Computationally Efficient Video Restoration For Nyquist Sampled Imaging Sensors Combining An Affine-Motion-Based Temporal Kalman Filter And Adaptive Wiener Filter, Michael Rucci, Russell Hardie, Kenneth Barnard
Computationally Efficient Video Restoration For Nyquist Sampled Imaging Sensors Combining An Affine-Motion-Based Temporal Kalman Filter And Adaptive Wiener Filter, Michael Rucci, Russell Hardie, Kenneth Barnard
Russell C. Hardie
In this paper, we present a computationally efficient video restoration algorithm to address both blur and noise for a Nyquist sampled imaging system. The proposed method utilizes a temporal Kalman filter followed by a correlation-model based spatial adaptive Wiener filter (AWF). The Kalman filter employs an affine background motion model and novel process-noise variance estimate. We also propose and demonstrate a new multidelay temporal Kalman filter designed to more robustly treat local motion. The AWF is a spatial operation that performs deconvolution and adapts to the spatially varying residual noise left in the Kalman filter stage. In image areas where …
Extended Permutation Filters And Their Application To Edge Enhancement, Russell Hardie, Kenneth Barner
Extended Permutation Filters And Their Application To Edge Enhancement, Russell Hardie, Kenneth Barner
Russell C. Hardie
Extended permutation (EP) filters are defined and analyzed. In particular, we focus on extended permutation rank selection (EPRS) filters. These filters are constrained to output an order statistic from an extended observation vector. This extended vector includes N observation samples and K statistics that are functions of the observation samples. The rank permutations from selected samples in this extended observation vector are used as the basis for selecting an order statistic output. We show that by including the sample mean in the extended observation vector, the filters exhibit excellent edge enhancement properties. We also show that several previously defined classes …
Applications Of High Throughput Screening Tools For Thermoelectric Materials, W. Wong-Ng, H. Joress, J. Martin, Y. Yan, M. Otani, E. Thomas, M. Green, Jason Hattrick-Simpers
Applications Of High Throughput Screening Tools For Thermoelectric Materials, W. Wong-Ng, H. Joress, J. Martin, Y. Yan, M. Otani, E. Thomas, M. Green, Jason Hattrick-Simpers
Jason R. Hattrick-Simpers
No abstract provided.