Computer and optical simulations of radar imaging systems.

摘要

A method for simulating radar range profiles from computer models of three-dimensional conducting targets is explored. The backscattered fields from a target, used to form its profile, are approximated using physical optics. Ray tracing is employed to determine the illuminated target surface required by physical optics. A database of simulated range profiles is created from computer models of five commercial aircraft.; Simulated radar range profiles from five different commercial aircraft models are used to investigate an aircraft identification algorithm based upon correlation filters. The effects of correlation filter width, multiple profiles, and target aspect information are examined. Reliable identification appears possible if both narrow correlation filters and several profiles are used in an identification. Additive system noise has little impact on the identification rate until the noise fluctuations become comparable to the inherent speckle fluctuations.; An iterative method for focusing inverse synthetic aperture radar (ISAR) images is studied using the database of simulated aircraft profiles. Blurring in ISAR images occurs when the target aspect does not vary linearly in time. Nine different target aspect scenarios are examined for each of the five aircraft. In most of the cases tested, the iterative method correctly, or nearly correctly, focuses the ISAR image even in presence of significant amounts of additive noise.; An experimental laser radar is constructed and tested which is designed to simulate delay-Doppler images from asteroids. Delay-Doppler data from this system will be used to test asteroid shape reconstruction methods. This laser radar is based upon a Michelson interferometer and uses a short coherence length laser diode to achieve a range resolution of 0.1 mm on targets up to 1.5 cm in diameter. The effectiveness of this system is demonstrated by examining a sphere, bolt, and two small stones.