Sparse frequency laser radar signal modeling and doppler processing

Date of Award

2010

Degree Name

M.S. in Electro-Optics

Department

Department of Electro-Optics and Photonics

Advisor/Chair

Advisor: Peter Powers

Abstract

Sparse frequency, linearly frequency modulated laser radar (ladar) signals achieve improved range resolution comparable to a larger signal bandwidth. From basic radar/ladar principles it is known that the bandwidth of a signal is inversely proportional to range resolution. Hence, the effective bandwidth of a ladar signal using sparse frequency techniques is larger than the bandwidth of each modulated laser frequency. Previous experiments have validated range resolution and peak to sidelobe ratio derived from models utilizing two segmented bandwidths. This thesis discusses the modeling with three segmented bandwidths. The model is verified against an experimental setup using three frequency offset lasers.The two segmented bandwidth, sparse frequency ladar signal is reexamined to include Doppler effects. The new modeling utilizes a coherent on receive setup allowing for phase information to be processed from the signal. The extracted phase information can be used to determine characteristics about a target, namely its speed and direction with respect to the receiver. This modeling was experimentally verified for cases where the target was next to the receiver, at a distance (simulated through a fiber delay line), and for multiple targets. As a final check of the modeling, the velocity determined from the phase information was compared against the velocity readout of a stage with a built in optical encoder.

Keywords

Optical radar, Doppler radar, Pulse frequency modulation, Signal processing

Rights Statement

Copyright © 2010, author

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