Impact of motion estimation errors on DVB-S based passive ISAR imaging

This work explores the effects of inaccuracies on the rotation motion estimation on DVB-S based passive ISAR images focused via Back-Projection Algorithm (BPA). BPA can produce images in a target fixed reference system, thus giving rise to the possibility of directly extracting relevant geometrical features from the ISAR products, such as target width and length; moreover, as the support region does not depend on the particular geometry/frequency, it is suitable for comparing/fusing image products achieved on different channels (even distributed and/ or operating on different bands). However, as the exploitation of satellite illuminators can complicate the target motion estimation task, the focusing must deal with inaccurate target kinematics information. In this work, after deriving the theoretical PSF, we derive the image pulse response under estimation errors on the yaw, pitch, and roll motions. Moreover, consequently distortions affecting the image are evaluated via closed-form equations. The theoretical findings are confirmed by experimental data analysis using a passive radar receiving system developed by FHR and an Astra satellite as opportunistic illuminator.