Scheme Design And Signal Processing Implementation Of A Frequency Stepped SAR Radar System

Synthetic Aperture Radar(SAR)is a kind of high-resolution radar.With the development of hardware platform and digital signal processing technology in recent decades,the application prospect and development potential of the SAR radar in the military and national fields have been greatly raised.Stepped frequency(SF)signal is a sort of waveform widely used in high-resolution radars in recent years.With transmitting and receiving a set of coherent pulses with different carrier frequencies,a radar can obtain high-resolution range images after radial image synthesis and reduce the instantaneous bandwidth.This thesis is based on a practical project.Combining with microwave three dimensions(3D)imaging technology,The scheme design and signal processing implementation of a 3D frequency stepped SAR radar system has been completed.Compared with traditional systems,this system has the capability of three-dimensional spatial imaging and avoiding environmental interference,and is suitable to perform external field measurements with higher accuracy and lower equipment cost.Firstly,the radar signal theory involved in the radar system is introduced.The frequency step signal,intermediate frequency sampling theorem,digital down-conversion technology,radar back projection algorithm(BP)are introduced and derived.And the BP algorithm is simulated.Then,the design scheme and specification of the radar hardware system are given,and the system's parameters are calculated and analyzed.This radar system consists of a radio frequency subsystem,a motion platform and a computer server group,and the design scheme of each module is discussed in detail.Next,based on the constructed hardware how the software of the radar system was developed is illustrated.The Verilog and C language are used to implement radar signal processing and control functions,including radar echo acquisition,digital downconversion processing,data transmission,and protocol analysis.In this part,a compensation method is proposed to fix the phase error caused by the structure of this system.Finally,aiming at the evaluation of the system function and performance,some tests have been run,including the system's acquisition function,data transferring performance,communication interface,and overall system performance.Some simulation softwares are used to analyze and verify the system test results.