Adaptive Viterbi-Based Range-Instantaneous Doppler Algorithm for ISAR Imaging of Ship Target at Sea

The range-instantaneous Doppler (RID) algorithm has been successfully used in high-resolution inverse synthetic aperture radar (ISAR) imaging of maneuvering ship targets. Parametric technique of RID is an important method to produce the well-focused RID ISAR images by estimating the parameters of received signal modeled as multicomponent polynomial-phase signals in each range bin. However, the cross terms of signals and false maxima of time-frequency distributions cause image blurring and the loss of fine detail. In this paper, we first propose a new time-frequency transform, named multiproduct high-order matched-phase transform (MPHMT), to suppress the cross terms and amplify the auto terms of signals. Then, an adaptive Viterbi search is proposed to select the optimal model parameters by an adaptive penalization function. Finally, associating MPHMT and adaptive Viterbi search with RID, we further propose the adaptive Viterbi-based RID algorithm for ISAR ship imaging. Simulation and real-data-based results demonstrate that our proposed algorithm is valid.