Movement Analysis And Compensation For ISAR Based On Non-stationary Platform

Inverse synthesis aperture radar(ISAR) system possess advantages including flexible radar carrying platform, long observation distance, precise target detection as well as easy access to high-resolution images of targets, which lead to more and more applications in military fields. With the extension of ISAR application areas, as to ISAR system, to load the radar on non-stationary platform will be a new development direction in the future.With the motion of target and radar analyzed detailedly in ISAR system on non-stationary platform, this paper elaborates a solution for coordinate processing in non-stationary platform mounted ISAR system,e.g., via transforming the position relationship between the three-dimensional rotation of radar and target into one reference coordinate system, proceeds echo imaging utilizing the conception of coordinate transformation. Simulation results verify the feasibility of the proposed coordinate processing scheme, fulfilling achievements of target images.The key in radar imaging lies in motion compensation, which demands pretreatments for signal. This paper introduces pretreatment techniques which are respectively based on minimum entropy criterion and maximum correlation criterion and applies the data processing algorithm of interpolation method as an auxiliary tool in the pretreatment, with the enhancement in signal pretreatment accuracy resulting from interpolation method verified through simulation. The next step of motion compensation is the fine alignment of preprocessed signal, which can be conducted by dominant scatterer method、constant phase difference elimination method and doppler centroid tracking method, among which the doppler centroid tracking method is superior in imaging performance by simulation analysis. The joint time-frequency analysis method can image synchronously through ISAR data, which removes the performance degeneration stemming from the complicated motion of radar and target. Fine alignment of signal can be realized by the joint time-frequency analysis method in ISAR system and simulation verifies that the corresponding imaging performance outstands compared to that of traditional ISAR system fine alignment.