Motion estimation and optimum time selection for ship ISAR imaging

The problem of angular motion estimation and optimum time selection for ship ISAR imaging is addressed. The aim is to estimate ship angular motion and to select proper imaging intervals in order to obtain high quality top-view or side-view ship images suitable for processing by classification/identification procedures. To this purpose a novel analytical model for the phase/Doppler frequency of the generic ship scatterer is derived and a new ISAR algorithm is proposed, able to adapt to the ship motion conditions estimating the time instants better suited for top-view of side-view image formation and the rotation motion vertical component for top-view image scaling. The performance of the complete ISAR technique is analysed under different ship models, ship motion, acquisition geometry and background conditions. Results of the application of the proposed technique to live ISAR data prove the effectiveness of the proposed approach.