Real-time Imaging Algorithm Design And System Development For Missile-borne Forward-side-looking SAR

SAR(Synthetic Aperture Radar, SAR for short) imaging technology used in missile terminal guidance stage has become a current research focus. The missile-borne SAR forward-side-looking imaging can obtain the real-time image of the location and landform features in advance. Thus the missile is guided to the region of interest at an ultra-high hit rate, which accounts for the irreplaceability of the precision-guided weapon in the modern war.While the axis direction of missile-borne platform antenna scanning is generally consistent with that of the missile, the common air-borne platform is almost vertical to the direction of flight. So some geometric relationship of missile-borne SAR cannot be fully used in the airborne case. This paper redefines the geometric relationship of the squint missile-borne SAR imaging mode, which is called missile-borne forward-side-looking imaging. In addition, considering the diversity of resolution in range and azimuth, ground surface and slant surface, and the disunity of the definition of resolution in relevant documents and books available, this paper reviews the various definitions of resolution and the relationship between each other in detail.This paper introduces the imaging modes at different stages of the terminal guidance, and then verifies the forward-side-looking imaging algorithm respectively for the SAR imaging in different operating modes(strip-map mode and spotlight mode). In particular, it designs imaging parameters and studies the motion compensation under the typical tactical trajectory background. With a high real-time requirement in view, a simple and mature RD-dechirp algorithm is chosen for its advantages of simple principle and low computation cost. Then a forward-side-looking real-time imaging algorithm combined with motion compensation is designed, followed by the demonstration of the feasibility of this algorithm and the validity of the motion compensation with real measured data. For the requirements of high real-time performance, system miniaturization, low power consumption and high reliability, a powerful hardware platform is needed. Missile-borne SAR real-time imaging signal processing system applied in this paper adopts multi-core and multi-DSP hardware architecture with one Virtex-6 FPGA and three pieces of DSP TMS320C6678. This paper commences with a brief introduction tothe signal processing system including the A/D data collecting module, FPGA master control module, DSP signal processing module, PC interface module and missile interface module. Then, it introduces the multi-core parallel scheme and procedure of the forward-side-looking missile-borne SAR imaging algorithm combined with the method for motion compensation. Finally, the application and verification of the parallel algorithm on the hardware system are proposed. The real-time character of this algorithm is also analyzed. To conclude, a semi-physical simulation platform consists of a hardware platform for signal processing and a PC software for display and control, the two of which are connected via Ethernet.