Separation and reconstruction of the rigid body and micro-Doppler signal in ISAR part I – theory

In radar imaging, the micro-Doppler effect is caused by fast movements of some scattering points on the target. These movements correspond to highly non-stationary components in the time-frequency domain of the signal. The rigid body can be considered as stationary at one range location during the processing time. This property is used to separate the micro-Doppler signal from the rigid body using the L-statistics. Since the rigid body can be considered as a sparse signal, its values can be fully recovered at the positions where the micro-Doppler and rigid body components overlap. The recovery is based on the compressive sensing theory and methods. After an overview of the methods, a quantitative analysis of the improvements achieved in the time-frequency-based separation is done. Moreover, a comparison with both the time and the frequency domain analysis is provided. Analysis of small additive noise influence to the reconstruction accuracy is done.