The Fast Doppler Parameter Estimation And Operating Mode Identification Of Space-borne SAR In Reconnaissance Mode

Owing to the advantages of high resolution,all-day and all-weather imaging,synthetic aperture radar(SAR)is widely applied in civil and military fields.In different application fields,the resolution and observation range requirements of SAR imaging are different as well.So far,most of space-borne SARs are operated in many different operating modes,including stripmap mode,spotlight mode and sliding spotlight mode.Due to the significant differences among different operating modes,the parameters and properties of the transmitted signals distinguish,which acquires different strategies when SAR is interfered.Therefore,it is important to estimate the Doppler parameters of space-borne SAR accurately and to discriminate the operating mode of the space-borne SAR electronic jamming technology.Based on the acquisition and estimation of space-borne SAR signals,the reception and recognition of low-intercept radar signals,Doppler parameter estimation and SAR image formation,a fast estimation algorithm based on Hough-Radon transform and the discrimination method of different operating modes of space-borne SAR are studied in this paper.Firstly,based on the analysis of the traditional Doppler centroid and Doppler frequency estimation algorithm,this paper points out that the traditional algorithms are not suitable for reconnaissance case due to the fact that the motion parameters and the full aperture data of the radar platform cannot be achieved in the reconnaissance.To overcome this issue,a fast estimation algorithm of Doppler parameters based on Hough-Radon transform is proposed in this paper.This algorithm not only guarantees the estimation accuracy of Doppler parameters,but also is more efficient than the modified algorithm based on Radon transform and more suitable for real-time processing.Secondly,this paper deeply analyzes the differences of received power and Doppler history in different operating modes of space-borne SAR,and builds the discriminant model of space-borne SAR based on received power and Doppler history.Using range parameter estimation,power compensation and so on,the accurate estimation of the received power is performed.Then the operating mode of the SAR is discriminated accurately based on the information of range paratmeter,Doppler parameter,and beam center power map.