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Information-theoretic performance bounding of Bayesian identifiers

Description: Statistical target recognition techniques perform well when the true'' target-signature data are deterministic. If the deterministic nature of the data exists and the probabilistic values of a given problem are known, then identifiers, based on Bayesian estimation theory, have great potential for solving the target identification problem. How well an identifier will perform is usually answered by Monte Carlo simulations or implementation experiments. An alternative to these performance analysis techniques is the use of information theory. Information theory has long been applied to the investigation of data compression, which deals with average distortional measures. The association of Bayes risk with distortion allows for information-theoretic tools to be applied to the statistical target identification problem. The rate-distortion function of data compression can be extended to the Bayes rate-distortion function. Derived from designer-specified risk and identifier structure, the theoretical Bayes rate-distortion function relates mutual information to the identifier performance. Mutual information is determined from the target-signature data used by the identifier and by the nature of the noise imposed upon the data. Computational efforts in determining mutual information values allow for identifier performance bounds to be extracted from the Bayes rate-distortion function.
Date: January 1, 1993
Creator: Briles, S.D.
Partner: UNT Libraries Government Documents Department

Power-aware improvement in signal detection.

Description: Improvements in signal detection characteristics for a remote-sensing instrument can be achieved at the expense of computational effort and the power associated with that effort. DSP used in remote sensing scenarios usually involves the detection of a signal and the estimation of parameters as sociated with that signal . Fortunately, the algorithms used for parameter estimation are the same algorithms which, through postprocessing decision making, decrease the false alarm rate . This post processing allows for the reduction in the false alarm rate as seen at the end product of the instrument . The level of false alarm reduction must be balanced against the amount of additional power that is needed to produce this level . This paper will present quantitative results that demonstrate this tradeoff for a specific application . This paper focuses on the detection of transient radio frequency (RF) events (e.g., lighting) as observed from the FORTE satellite . However the methodology presented for power-aware improvement in signal detection is general enough to be applied to most remote-sensing scenarios . A suite of algorithms, which vary widely in their precision of estimated parameters, is presented in the paper . Equally wide in variation is the amount of power required by each of the algorithms. Power requirements of the algorithms were obtained by actual physical measurement for a mimic of a RAD750 processor . Algorithm performance was determined via Monte Carlo testing . Using that same Monte Carlo testing post-pro ce ssing, thresholds for each of the algorithms were developed for the reduction of the false alarm rate. A quantitative display of how each of the algorithms decreases the false alarm rate over the front-end analog detection is displayed versus the power required.
Date: January 1, 2003
Creator: Briles, S. D. (Scott D.); Shriver, P. M. (Patrick M.); Gokhale, M. (Maya) & Harikumar, J. (Jayashree)
Partner: UNT Libraries Government Documents Department

Analysis and System Design Framework for Infrared Spatial Heterodyne Spectrometers

Description: The authors present a preliminary analysis and design framework developed for the evaluation and optimization of infrared, Imaging Spatial Heterodyne Spectrometer (SHS) electro-optic systems. Commensurate with conventional interferometric spectrometers, SHS modeling requires an integrated analysis environment for rigorous evaluation of system error propagation due to detection process, detection noise, system motion, retrieval algorithm and calibration algorithm. The analysis tools provide for optimization of critical system parameters and components including : (1) optical aperture, f-number, and spectral transmission, (2) SHS interferometer grating and Littrow parameters, and (3) image plane requirements as well as cold shield, optical filtering, and focal-plane dimensions, pixel dimensions and quantum efficiency, (4) SHS spatial and temporal sampling parameters, and (5) retrieval and calibration algorithm issues.
Date: April 5, 1999
Creator: Cooke, B.J.; Smith, B.W.; Laubscher, B.E.; Villeneuve, P.V. & Briles, S.D.
Partner: UNT Libraries Government Documents Department

Classification of RF transients in space using digital signal processing and neural network techniques

Description: The FORTE{prime} (Fast On-Orbit Recording of Transient Events) small satellite experiment scheduled for launch in October, 1995 will attempt to measure and classify electromagnetic transients as sensed from space. The FORTE{prime} payload will employ an Event Classifier to perform onboard classification of radio frequency transients from terrestrial sources such as lightning. These transients are often dominated by a constantly changing assortment of man-made ``clutter`` such as TV, FM, and radar signals. The FORTE{prime} Event Classifier, or EC, uses specialized hardware to implement various signal processing and neural network algorithms. The resulting system can process and classify digitized records of several thousand samples onboard the spacecraft at rates of about a second per record. In addition to reducing dowlink rates, the EC minimizes command uplink data by normally using uploaded algorithm sequences rather than full code modules (although it is possible for full code modules to be uploaded from the ground). The FORTE{prime} Event Classifier experiment combines science and engineering in an evolutionary step toward useful and robust adaptive processing systems in space.
Date: February 1, 1995
Creator: Moore, K. R.; Blain, P. C.; Briles, S. D. & Jones, R. G.
Partner: UNT Libraries Government Documents Department

Coherent electromagnetic field imaging through Fourier transform heterodyne

Description: The authors present a detection process capable of directly imaging the transverse amplitude, phase, and if desired, Doppler shift of coherent electromagnetic fields. Based on coherent detection principles governing conventional heterodyned RADAR/LIDAR systems, Fourier Transform Heterodyne (FTH) incorporates transverse spatial encoding of the local oscillator for image capture. Appropriate selection of spatial encoding functions, or basis set, allows image retrieval by way of classic Fourier manipulations. Of practical interest: (1) imaging is accomplished on a single element detector requiring no additional scanning or moving components, and (2) a wide variety of appropriate spatial encoding functions exist that may be adaptively configured in real-time for applications requiring optimal detection. In this paper, they introduce the underlying principles governing FTH imaging, followed by demonstration of concept via a simple experimental setup based on a HeNe laser and a 69 element spatial phase modulator.
Date: December 1998
Creator: Cooke, B. J.; Laubscher, B. E.; Olivas, N. L.; Goeller, R. M.; Cafferty, M.; Briles, S. D. et al.
Partner: UNT Libraries Government Documents Department