Passive Synthetic Aperture Hitchhiker Imaging of Ground Moving Targets—Part 2: Performance Analysis

In Part 1 of this paper, we present a passive synthetic aperture imaging and velocity estimation method for ground moving targets using a network of passive receivers. The method involves inversion of a Radon transform-type forward model via a novel filtered backprojection approach combined with entropy optimization. The method is applicable to noncooperative transmitters of opportunity where the transmitter locations and transmitted waveforms are unknown. Furthermore, it can image multiple targets moving at different velocities in arbitrary imaging geometries. In this paper, we present a detailed analysis of the performance of our method. First the resolution analysis in position and velocity spaces is presented. The analysis identifies several factors that contribute positively or negativity toward position and velocity resolution. Next, we present a novel theory to analyze and predict smearing artifacts in position images due to error in velocity estimation of moving targets. Specifically, we show that small errors in the velocity estimation result in small positioning errors. We present extensive numerical simulations to demonstrate the theoretical results. While our primary interest lies in radar, the theory, methods, and algorithms introduced in this paper are also applicable to passive acoustic, seismic, and microwave imaging.