Analysis and Simulation of the Micro-Doppler Signature of a Ship With a Rotating Shipborne Radar at Different Observation Angles

Differences in the motion of different parts of a target cause the echo signal to contain specific Doppler modulation information, i.e., the micro-Doppler (m-D) effect. This phenomenon provides an effective way to detect targets in marine environments. In this study, based on the establishment of the micromotion model of a rotating surveillance radar and analysis of the m-D frequency, the geometrical optics and physical optics (GO-PO) method and the time-frequency analysis technique are used to obtain the radar cross section (RCS) and m-D signature of a ship with a shipborne radar at different observation angles. The ship, as the main component of the echo, is associated with the main energy. Finding the optimum angle to observe the shipborne radar is of great importance. The results show that the m-D signatures of the shipborne radar are not clear when the elevation angle is greater than 60 degrees but are clear when the elevation angle is less than 55 degrees. Moreover, some motion parameters can be extracted from the m-D signature, such as the period of the ship micromotion. The rotation speed of the shipborne radar can be obtained and is consistent with the set speed. This can help identify and track the key parts of a ship with local motion.