Research Of UAV SAR Multi-mode Imaging Real-time Processing

Synthetic Aperture Radar(SAR)works in microwave band,with the advantages of all-day,all-weather,long distance,and high resolution imaging,etc.SAR is usually fixed on the motor vehicles.According to different vehicles,SAR can be divided into space-borne,missile-borne,airborne,and UAV SAR,etc.According to different perspective,SAR can be divided into positive side,squint-looking,and forward-looking SAR,etc.According to how the SAR works,it can be divided into strip-map,spotlight,and scan SAR,etc.This paper proposes an UAV SAR multi-mode imaging algorithm which is compatible with positive side strip-map mode and squint-looking sliding spotlight mode.The algorithm effectively combines with the azimuth variant error compensation and phase gradient autofocus,and applies to three kinds of imaging resolution as 3m,1m and 0.5m.The functional requirements of the entire radar system for SAR real-time imaging system include: Produce PRF signal by external incoming frequency synthesizer,which control the working state of the radar system.Produce some auxiliary signal basing on the PRF signal at the same time.Receive the echo analog signal and convert it into digital signal for imaging processing.Finally get and save the scene imaging results.Receive the inertial navigation information which is used as parameters for imaging processing.Produce servo control signal according to the inertial navigation information at the same time.Save the effective original echo data on board experiment,that is convenient for analyzing working conditions on the ground.This paper completes the complex processing tasks around the signal processing board in the SAR Real-time imaging system.The signal processing board consists mainly of FPGA and DSP.In view of the strong demand in the field of high performance computing,TI launched the series of TMS320C66 x multi-core DSP based on Keystone architecture,which perfectly realized the low power consumption and high performance.As the flagship product among the series of TMS320C66 x products,TMS320C6678 integrated eight processors into a chip is the strongest DSP in floating-point and fixed-point operation currently.It also has a wealth of interface resources and storage structure,which can satisfy the needs of the performance of real-time signal processing and high speed data transmission.This paper develops the UAV SAR multi-mode imaging real-time processing software based on theTMS320C6678,and introduces the programming method of SAR imaging algorithm on multi-core DSP in detail.