Passive imaging of moving targets using distributed apertures in multiple-scattering environments

Abstract

We present a novel passive image formation method for moving targets using distributed apertures capable of exploiting information about multiple-scattering in the environment. We assume that the environment is illuminated by non-cooperative transmitters of opportunity with unknown location and unknown transmitted waveforms. We develop a passive measurement model that relates the scattered field from moving targets at a given receiver to the scattered field at other receivers. We formulate the passive imaging problem as a generalized likelihood ratio test for a hypothetical target located at an unknown position, moving with an unknown velocity. We design a linear discriminant functional by maximizing the Signal-to-Noise Ratio (SNR) of the test-statistic, and use the resulting position- and velocity-resolved test-statistic to form the image. Our imaging method can determine the two- or three-dimensional velocity vector as well as the two- or three-dimensional position vector of a moving target without the knowledge of transmitter locations and transmitted waveforms. We present numerical experiments to demonstrate the performance of our passive imaging method operating in multiplescattering environments. The results show that the point spread function of the reconstructed images improves when the information about multiple scattering is exploited.