Bistatic ISAR envelope alignment algorithm based on orbit error search

Aiming at the application of space objects, a bistatic inverse synthetic aperture radar envelope alignment algorithm based on orbit information is proposed. Firstly, the relationship between the orbit position prediction error and the slow time is deduced, the analysis shows that the orbit prediction error in imaging time can be expressed by the second order function of slow time. On this basis, the precise envelope alignment of the one-dimensional range profile is achieved by compensating the phase in the frequency domain using the orbit prediction value and the orbit error search result. In the process of parameter search, the searching step of error velocity and acceleration is determined, and the contrast of the two-dimensional image is taken as the cost function. The simulation results show that the proposed algorithm is more suitable for bistatic echo with lower signal-to-noise ratio due to bistatic angle and polarization mismatch, compared with the traditional envelope alignment algorithm based on echo correlation.