Date of Award
Doctor of Philosophy
Benjamin C. Flores
Compared to high range resolution radar systems, chaotic LADAR (laser detection and ranging) has the potential of providing an increase in range-Doppler resolution by several orders of magnitude.
The purpose of this project is to determine system parameters and signal processing schemes required to build a high resolution chaotic LADAR. Specifically, the LADAR is based on a semiconductor laser that generates a wideband chaotic signal via optical feedback. The behavior of the laser output is modeled by changing the control parameters of the delay differential equations that dictate the behavior of the laser output. Depending on the feedback level and the external cavity length the output of the laser, a route to chaotic behavior is found. Experiments show that the power spectral density and autocorrelation of the electric field of the laser output can be controlled for maximum range resolution. Further tests yield a process to optimize the entropy of the signal, autocorrelation sidelobe levels, Lyapunov exponent of the system and statistical properties of the signal. An ideal signal is obtained for a feedback level of 0.05 and an external cavity length of 0.30 m. The corresponding spectrum has a compression bandwidth of 22.12GHz.
In addition, a full analysis of the ambiguity function reveals that the optimized chaotic electric field has a "thumbtack shape" which is ideal for obtaining range and Doppler information. A range resolution of 6.7mm and a pedestal level -30dB is achieved. For illustrative purposes, the signature of a Boeing 777 is modeled using hot spots. The quality of the image is measured in terms of its entropy. Extremely low Doppler sidelobes are obtained.
Received from ProQuest
Verdin, Berenice, "Characterization of high resolution range and Doppler chaotic LADAR" (2009). Open Access Theses & Dissertations. 378.