Time-frequency separation of multiple moving radar targets

When multiple radar targets are close to each other, the return signals form these targets are overlapped in time. Therefore, by applying conventional motion compensation algorithms designed for single target, the multiple targets cannot be resolved, and each individual target cannot be clearly imaged. However, each individual target may have its own velocity and direction different from others. These different Doppler histories can be utilized to separate target from each other. By taking time-frequency transforms, different Doppler changing rates can be estimated. Using each estimated Doppler changing rate and making phase correction, each individual target may be imaged. In this paper, we first review algorithms for radar imaging of multiple moving targets, then, analyze the performance of these algorithms, and, finally discuss the advantages and limitations of these algorithms by using simulated radar data.