The primary goad of this project is the development of signal processing algorithms that reliably detect and image targets embedded in a medium of stationary and randomly distributed scatterers. The major contribution of this work is a detailed study of the relationship between scattering structures and the phase behavior of back-scattered signals with respect to frequency and space. Analytical investigations and computer simulations are being developed for predicting the resultant signal features for noise and target echoes by integrating the deterministic and statistical relationships between the signal wavelength, scatterer size, and scatterer spatial distribution. Experimental investigations are being carried out in parallel with the analytical analysis and computer simulations. Data collected from various material samples with known flaws, and statistical characterizations of the phase and amplitude behavior over frequency and spatial variations are used to validate theoretical predictions. In addition, design procedures are being examined for developing adaptive nonlinear detectors that utilize frequency-diverse properties of the signals. The results of this study will identify critical signal features for the development of enhanced signal imaging and detection algorithms.
