Spaceborne Synthetic Aperture Radar System Design And Simulation Software

Synthetic Aperture Radar (SAR), as a high resolution microwave instrument, has an important status in the remote sensing. Its ability to image large planetary areas in all weather during day and night makes it progressed in the space to earth observation applications. Compute Aided Design (CAD) plays an indelible part in the procedure of spaceborne SAR design, analysis, simulation and emulation. In this dissertation, a set of SAR system design and simulation software is developed. It can reduce the calculation and make it easy to evaluate and decide the system, and optimize the performance of systems, improve efficiency and quality. The software has been used in many projects such as dual-frequency multi-polarization and multi-modes SAR system, environment disaster inspection and forecasting SAR satellite etc.This dissertation first considers the geometry relations between spaceborne radar and the earth targets. The conventional sphere model of earth and circle model of orbit are discarded, and the ellipsoid model and the ellipse model are selected for further research, which achieves a method to determine the target position through the antenna pointing direction. And the spaceborne SAR system design and simulation software is brought forth. This software accomplishes SAR system coefficients design for antenna area, pulse repetition frequency, signal bandwidth, downlink data rate, radar transmitter power and satellite platform yaw steering. And it also analysis the radar performance such as radar Doppler properties, radar system ambiguities and target location accuracy. And the software carries out the radar echoes simulation.This dissertation is devoted to: 1. This dissertation adopts the modularization programming method to develop thespaceborne SAR system design and simulation software, which obtains theWindows common interface and logical integrated structure, convenient forusage, maintenance and function extension.2. As for the earth model and orbit model, according to the properties of spaceborne SAR operation, in this dissertation, we reject the sphere earth model and circle orbit model and present a novel way to solve spaceborne geometry relations between radar and target by three ellipses, and achieve the way to determine the target position by antenna pointing direction. This method offers more precise geometry for spaceborne SAR system design and simulation.3. In the analyzing on the radar Doppler properties, under the ellipsoid earth model and ellipse orbit model, considering the earth rotation, the radar Doppler properties with different orbit eccentricity are compared, and the fact that orbit eccentricity affects Doppler frequency rate is found.4. On the base of deep discussing about spaceborne SAR operation, we present an approach to acquire the target location plane by satellite position and platform attitude, then to locate the target consistent with the earth surface curvature. In conformity with this means, we study that the changing of radar and platform coefficients influences the target location, and present the way to analyze the location accuracy through the platform position accuracy, platform attitude stability and radar timing accuracy.5. On the aspect of spaceborne SAR simulation, after thoroughly analyzing on the representative spaceborne SAR simulator, we grasp the spaceborne SAR operation procedure, and present a system simulation approach based on radar signal flow. This approach can simulate not only the radar echo reality, but also some subsystems' influence on system. The experiments have shown that this method simulates the spaceborne SAR system operation effectively and correctly.