| Bistatic SAR is a system that uses spatially separated transmitters and receivers.Global Navigation Satellite Systems Bi SAR is a subclass of Bistatic SAR.In this configuration,navigation satellites are used as transmitters of opportunity,while the receiver could be on board an aircraft or fixed on top of building.GNSS based passive SAR has well coverage,strong elusiveness and anti-interference ability.This dissertation focuses on the characteristics of,image algorithm,multiple satellite selection and configuration design.The main contents are as follows:1.This paper compares the performance of GNSS as transmitters from signal bandwidth,power budget,coverage capability and synchronization.This paper selects GALILEO as transmitters.The signal characteristics of GALILEO are analysed from frequency plan,modulation method and pseudo-code generation.2.In order to solve the problem of imaging focus of GNSS-BiSAR,GNSS-BiSAR signal model is established,the space-variant in range migration and Doppler of GNSS-BiSAR are analysed,Then we adopt extension Keystone transform and azimuth nonlinear CS frequency domain imaging algorithm.It solves the problem of focusing in azimuth and implements high resolution imaging.3.Based on generalized ambiguity function,the spatial resolution model is established.The characteristic of two dimensional resolution unbalance due to narrow signal bandwidth of transmitters.Taking the non-coherent information fusion method under multiple satellites illuminating to enhance the spatial resolution performance.4.Studying the main geometric parameters influencing the imaging performance of the GNSS-Bi SAR.The particle swarm optimization is proposed to implement the selection of the multiple satellites and configuration design criteria with the minimum resolution cell area and the optimal SNR.The validity of of the methods mentioned above are verified by theory analysis and numerical simulation.The results demonstrate that above methods can solve corresponding problems. |
PDF Full Text Request