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Full-Text Articles in Engineering
Modified Multiple Model Adaptive Estimation (M3Ae) For Simultaneous Parameter And State Estimation, Mikel M. Miller
Modified Multiple Model Adaptive Estimation (M3Ae) For Simultaneous Parameter And State Estimation, Mikel M. Miller
Theses and Dissertations
In many estimation problems, it is desired to estimate system states and parameters simultaneously. However, inherent to traditional estimation architectures of the past, the designer has had to make a trade-off decision between designs intended for accurate state estimation versus designs concerned with accurate parameter estimation. This research develops one solution to this trade-off decision by proposing a new architecture based on Kalman filtering (KF) and Multiple Model Adaptive Estimation (MMAE) techniques. This new architecture, the Modified-MMAE (M3AE), exploits the benefits of an MMAE designed for accurate parameter estimation, and yet performs at least as well in state …
Evaluation Of A Maximum A-Posteriori Slope Estimator For A Hartmann Wavefront Sensor, Troy B. Van Caster
Evaluation Of A Maximum A-Posteriori Slope Estimator For A Hartmann Wavefront Sensor, Troy B. Van Caster
Theses and Dissertations
Current methods for estimating the wavefront slope at the aperture of a telescope using a Hartmann wavefront sensor are based upon a centroid shift estimator. The centroid shift estimator determines the displacement, or shift, of the centroid off the optical axis using a moment calculation of the intensity distributions recorded in each subaperture. This centroid shift is proportional to the average slope of the wavefront in each subaperture. A maximum a-posteriori (MAP) slope estimator takes advantage of a-priori knowledge of the wavefront slope statistics and total irradiance falling on the subaperture detector arrays when determining the shift estimate. In order …
Atmospheric Turbulence Scintillation Effects On Wavefront Tilt Estimation, James A. Louthain
Atmospheric Turbulence Scintillation Effects On Wavefront Tilt Estimation, James A. Louthain
Theses and Dissertations
A new atmospheric turbulence screen generator is developed for use in performance calculations of adaptive optics systems valid over a wide range of atmospheric turbulence parameters. The screen generator accounts for diffraction effects caused by weak turbulence and incorporates the phase, amplitude, and cross statistics of the perturbed optical field. The wavefront's phase and amplitude perturbations are taken from the correlation functions developed by Lee and Harp and the cross correlation of the phase and amplitude derived in this thesis. The screen generator uses a modal representation to perform a Fourier series expansion of the wavefront phase and amplitude over …
Computer Simulation Of A General Purpose Satellite Modem, William L. Montgomery Jr.
Computer Simulation Of A General Purpose Satellite Modem, William L. Montgomery Jr.
Theses and Dissertations
The purpose of this research was to model and simulate the performance of a digital phase shift keyed satellite modem. The probability of bit error (P sub b) at different levels of energy per bit to noise power ratio (E sub b/N sub o) was the performance measure. The channel was assumed to contribute only additive white Gaussian noise. A second order Costas loop performs demodulation in the modem and was the key part of the simulation. The Costas loop with second order Butterworth arm filters was tested by finding the response to a phase or frequency step. The Costas …