Radar imaging of multiple moving targets

In this paper, we discuss the issue of radar imaging of multiple moving targets. When multiple moving targets are close to each other, the return signals from these targets are overlapped in time. Thus, by applying conventional motion compensation algorithms, when targets have rotational motion or maneuvering, multiple targets may not be resolved and each individual target cannot be clearly imaged. However, in cases where each individual target has its own velocity and moving direction different from others, then the different Doppler histories can be utilized to separate targets from each others. First we describe multiple target resolution. Then: we introduce the time-frequency based phase correction algorithm and discuss its limitation. Based on our previous work on time-frequency image formation, we propose a new method for radar imaging of multiple moving targets. With the new method, targets can be either point or extended targets, and target's motion can be either translational or rotational motion. Some examples are given for comparing the new method with the conventional Fourier method and time-frequency based phase correction methods.