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Systems and Communications Commons

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Full-Text Articles in Systems and Communications

Design Of Acousto-Optic Chaos Based Secure Free-Space Optical Communication Links, Anjan K. Ghosh, Pramode K. Verma, Samuel Cheng, Robert C. Huck, Monish Ranjan Chatterjee, Mohammed A. Al-Saedi Aug 2009

Design Of Acousto-Optic Chaos Based Secure Free-Space Optical Communication Links, Anjan K. Ghosh, Pramode K. Verma, Samuel Cheng, Robert C. Huck, Monish Ranjan Chatterjee, Mohammed A. Al-Saedi

Electrical and Computer Engineering Faculty Publications

We discuss the design of an acousto-optic cell based free space optical communication link where the data beam is made secure through chaos encryption. Using external signal modulation of the diffracted light from a hybrid acousto-optic cell chaos (or directly via incorporation in the sound-cell driver's bias voltage) encryption of data is possible. We have shown numerically that decryption of the encoded data is possible by using an identical acousto-optic system in the receiver.


Probability Density Functions For Snir In Ds-Cdma, David W. Matolak Jun 2009

Probability Density Functions For Snir In Ds-Cdma, David W. Matolak

Faculty Publications

Analytical expressions for the probability density function of block-wise signal-to-noise-plus-interference ratio for both synchronous and asynchronous direct-sequence spread spectrum code-division multiple access systems are developed, for equal average energy signals on the Gaussian and Rayleigh flat fading channels. Using the standard Gaussian approximation for multi-user interference, accurate density approximations are obtained, which agree very well with computer simulation results.


Misregistration In Adaptive Optics Systems, Nathan D. Engstrom Mar 2009

Misregistration In Adaptive Optics Systems, Nathan D. Engstrom

Theses and Dissertations

An adaptive optics (AO) system is most effective when there is a known alignment between the wave front sensor (WFS) and the deformable mirror (DM). Misregistration is the term for the unknown alignment between the WFS and DM. Misregistration degrades system performance and can make the system unstable. An AO system uses a reconstruction matrix to transform WFS measurements into DM commands. A standard AO system uses a model reconstruction matrix that assumes perfect registration between the WFS and DM. The object of this research is to mitigate the negative effects of misregistration by using offline WFS measurements to create …