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Electrical and Computer Engineering

Brigham Young University

2002

Articles 1 - 6 of 6

Full-Text Articles in Engineering

An Assessment Of Seawinds On Quikscat Wind Retrieval, David Draper, David G. Long Dec 2002

An Assessment Of Seawinds On Quikscat Wind Retrieval, David Draper, David G. Long

Faculty Publications

The scatterometer ocean wind retrieval process produces several possible solutions or ambiguities at each point, requiring a separate ambiguity selection step to infer a unique wind vector field. An ambiguity selection error occurs when the selected wind vector is not the closest ambiguity to the true wind. The current ambiguity selection routine for SeaWinds is ad hoc, but performs well under most circumstances. Factors such as instrument noise and rain can also cause the estimated wind flow to deviate from the true wind. A quality assurance (QA) analysis is performed to assess the ambiguity selection effectiveness and noise level of …

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Experimental Demonstration Of Multiple Robot Cooperative Target Intercept, Timothy W. Mclain, Randal W. Beard, Jed M. Kelsey Aug 2002

Experimental Demonstration Of Multiple Robot Cooperative Target Intercept, Timothy W. Mclain, Randal W. Beard, Jed M. Kelsey

Faculty Publications

This paper presents experimental results for the simultaneous intercept of preassigned targets by a team of mobile robots. The robots are programmed to mimic the dynamic behavior of unmanned air vehicles in constant-altitude flight. In proceeding to their targets, robots must avoid both known static threats and pop-up threats. An overview of the cooperative control strategy followed is given, as well as a description of the robot hardware and software used. Experimental results demonstrating simultaneous intercept of targets by the robot team are presented.

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Validation Of Sea Ice Motion From Quikscat With Those From Ssm/I And Buoy, David G. Long, Yunhe Zhao, Antony K. Liu Jun 2002

Validation Of Sea Ice Motion From Quikscat With Those From Ssm/I And Buoy, David G. Long, Yunhe Zhao, Antony K. Liu

Faculty Publications

Arctic sea ice motion for the period from October 1999 to March 2000 derived from QuikSCAT and ocean buoy observations. Special Sensor Microwave/Imager (SSM/I) data using the wavelet analysis method agrees well with ocean buoy observations. Results from QuikSCAT and SSM/I are compatible when compared with buoy observations and complement each other. Sea ice drift merged from daily results from QuikSCAT, SSM/I, and buoy data gives more complete coverage of sea ice motion. Based on observations of six months of sea ice motion maps, the sea ice motion maps in the Arctic derived from QuikSCAT data appear to have smoother …

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Modeling The Indoor Mimo Wireless Channel, Michael A. Jensen, Jon W. Wallace May 2002

Modeling The Indoor Mimo Wireless Channel, Michael A. Jensen, Jon W. Wallace

Faculty Publications

This paper demonstrates the ability of a physically based statistical multipath propagation model to match capacity statistics and pairwise magnitude and phase distributions of measured 4 x 4 and 10 x 10 narrow-band multiple-input multiple-output data (MIMO) at 2.4 GHz. The model is compared to simpler statistical models based on the multivariate complex normal distribution with either complex envelope or power correlation. The comparison is facilitated by computing channel element covariance matrices for fixed sets of multipath statistics. Multipolarization data is used to demonstrate a simple method for modeling dual-polarization arrays.

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Evaluation Of A Compound Probability Model With Tower-Mounted Scatterometer Data, David G. Long, Benjamin E. Barrowes Jan 2002

Evaluation Of A Compound Probability Model With Tower-Mounted Scatterometer Data, David G. Long, Benjamin E. Barrowes

Faculty Publications

Six months of data from the YSCAT94 experiment conducted at the CCIW WAVES research platform on Lake Ontario, Canada, are analyzed to evaluate a compound probability model. YSCAT was an ultrawideband small footprint (ap 1 m) microwave scatterometer that operated at frequencies of 2-18 GHz, incidence angles from 0° to 60°, both h-pol and v-pol, and which tracked the wind using simultaneous weather measurements. The probability distribution function of the measured instantaneous backscattered amplitude (p(a)) is compared to theoretical distributions developed from-the composite model and a simple wave spectrum. Model parameters of the resulting Rayleigh/generalized lognormal distribution probability density function …

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Reliability Of Programmable Input/Output Pins In The Presence Of Configuration Upsets, Paul S. Graham, Nathaniel Rollins, Michael J. Wirthlin, Michael P. Caffrey Jan 2002

Reliability Of Programmable Input/Output Pins In The Presence Of Configuration Upsets, Paul S. Graham, Nathaniel Rollins, Michael J. Wirthlin, Michael P. Caffrey

Faculty Publications

Sponsorship: Los Alamos National Laboratories (LA-UR-02-3163). Field programmable gate arrays (FPGAs) are an attractive alternative for space-based remote sensing applications. However, SRAM-based FPGAs are sensitive to radiation induced single-event upsets within the configuration memory. Such configuration upsets may change the logic, routing, and operating modes of a user FPGA design. Upsets within the configuration of an I/O block are especially troublesome as they may impact the operation of other system components. This paper will evaluate the operation of the I/O block within the Xilinx Virtex FPGA in the presence of configuration memory upsets and introduce techniques for detecting and repairing …

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