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This dissertation provides the conceptual development, modeling and simulation, physical implementation, and measured hardware results for a practicable digital coherent chaotic communication system. Such systems are highly desirable for robust communications due to the maximal entropy signal characteristics that satisfy Shannon's ideal noise-like waveform and provide optimal data transmission across a flat communications channel. At the core of the coherent chaotic communications system is a fully digital chaotic circuit, providing an efficiently controllable mechanism that overcomes the traditional bottleneck of chaotic circuit state synchronization. The analytical, simulation, and hardware results yield a generalization of direct sequence spread spectrum waveforms, that can be further extended to create a new class of maximal entropy waveforms suitable for optimized channel performance, maximal entropy transmission of chaotically spread amplitude modulated data constellations, and permission-based multiple access systems.

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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by Lo Wai Shun. / Bibliography: leaves 135-136 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

In this thesis we investigate what modern nonlinear-dynamical methods can tell us about some longstanding problems in atomic physics. It is well-known that it is very difficult to prevent electronic wavepackets from spreading, and that is where we bring in coherent states. We evaluate two strategies for forming coherent states in atomic physics problems with large Coriolis interactions : One involves the use of the "Cranked Oscillator" model to construct nondispersive wavepackets. We show that it is possible to keep the wavepackets from spreading while manipulating them with dipole fields with arbitrary time profiles. The second strategy involves using additional external fields to create a stable outer minimum far from the core. Whenever this minimum approximates a harmonic well it has its own subset of near-harmonic eigenstates and nearly-coherent states can be constructed. As examples of this strategy we study two-particle ion pair systems in a applied homogeneous magnetic field, and a weakly bound heavy-ion pair (Hydrogen positive and negative ions), where the nonspreading wavepacket corresponds to the motion of the drifting electron-ion or heavy ion pair in relative coordinates. We look for a Horseshoe Construction in the dynamics of the ionization of a highly excited two-electron atom by an classical-mechanical investigation.

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