Range Alignment and Motion Compensation for Missile-Borne Frequency Stepped Chirp Radar
One of the difficulties for frequency stepped chirp radar (FSCR) is to resolve the range-Doppler coupling due to relative motion between the radar and the target. Motion compensation is usually adopted to solve the problem in realizing synthetic high range resolution profile (HRRP) for a moving target. For missile-borne FSCR, the range migration of target echo during a coherent processing interval, which is resulted from the high speed motion of missile, is serious and will affect target detection and synthetic high range resolution profile. Therefore, range migration correction and motion compensation are very important for missile-borne FSCR signal processing. In the paper, with the background of terminal guidance anti-ship FSCR seeker, the range alignment is accomplished in frequency domain during the process of real-time digital pulse compression. Then an effective velocity estimation algorithm based on the waveform entropy of the Doppler amplitude spectrum of target echoes is addressed and the velocity estimation accuracy is derived. Finally, the simulation indicates that the new method can estimate the radial velocity accurately and reconstruct the distorted HRRP successfully. In addition, the method has good anti-noise performance and works in the scenario of multi-target with different velocities as well.