ASYMPTOTIC ANALYSIS MODELS FOR MOVING PLATFORM MULTIPATH WITH APPLICATIONS TO SIGNAL PROCESSING

In radar engagements involving moving platforms near a sea surface, multipath strongly affects the received signal. The signal distortion induced by the multipath can have a serious impact on the effectiveness of target localization algorithms and electronic countermeasure techniques. The problem of interest in this research is to determine the statistical behavior of the received signal and investigate the dependence of these statistics on relative transmitter-receiver-sea surface motion. This analysis results in a second order statistical characterization of the received signal. This statistical characterization forms the basis for two important signal processing algorithms. These are differential doppler frequency and time delay estimation using an array receiver.; In this dissertation we use a quasi-stationary, composite surface scattering model. Specifically, we first assume the sea surface and receiver/transmitter to be frozen in time. The statistics of the received signal evolve in time according to the changing scattering geometry and the dynamics of the sea surface motion.; In our research the sea surface is modeled as a Gaussian process characterized by its spectrum. An analytical technique is used to decompose the surface into two contiguous regimes--long gravity waves and high frequency capillary waves. This decomposition provides a natural basis for the use of a composite scattering model. The forward scatter model we use here employs the vector Kirchhoff integral formulation to treat both high and low frequency surface scatter components. An asymptotic expansion of the field and its statistics is developed using surface slopes as parameters. This analysis extends previous results to explicitly treat the case of forward scatter from a time-varying random surface with moving sources.