Micro-Doppler Removal in the Radar Imaging Analysis

The micro-Doppler (m-D) effect is caused by fast moving reflectors. This effect may significantly decrease the readability of the inverse synthetic aperture radar/synthetic aperture radar (ISAR/SAR) images. An L-statistics-based method for m-D effects removal is proposed. The L-statistics approach is performed on the spectrogram, while the rigid body signal synthesis is done in the complex time-frequency (TF) domain. The proposed method is very simple to use and produces better results than the other TF-based approaches. In addition to being capable of separating the rigid body and the m-D parts, this approach is robust to the noise influence. It may also separate close rigid body points, which are not separated in the original radar image. In the numerical implementation of this approach for radar imaging, the computational efficiency is further improved by using two thresholds. The first threshold determines whether there is a target signal in a range cell, while the second threshold determines whether there are m-D effects in this range cell. These thresholds could significantly decrease the computation time in real-time applications. The theory is illustrated by examples.