Motion Compensation Of Synthetic Aperture Radar And Imaging Algorithm

Due to microwave imaging technology of all-time, all-weather characteristics inthe field of civil and military plays an important role, Synthetic aperture radartechnology has made significant scientific more than30years of development andtechnological achievements and technological breakthroughs. Radar beam irradiationdirection perpendicular to the direction of movement of the sensing means, theantenna produce linear FM signal and receive it to the memory after the surfacereflectance. SAR has a variety of operating modes, stripmap SAR: The motion of theradar platform moves in a uniform way, but the directivity of the antenna remainsunchanged. This operating mode can imaging a strip of tape on the ground. Scan SAR:The difference of this mode of operation and the strip mode is that the antenna scansground multiple times. Spotlight SAR: To achieve precise imaging over the region ofinterest, we can control the antenna beam pointing. ISAR: the SAR work mode is thistarget static and radar moves, but in ISAR work mode the target is move and radar isstatic. Bistatic SAR: In this mode, the receiver and transmitter in a different location.Interference SAR: through the post-processing of complex image to extract terrainheight and displacement, Conjugate through adjacent positions of the complex imagecan be obtained a high degree of interference.The main contents are as follows:1. The basic knowledge of SAR imaging. The work principle of SAR, thegeometric relationship of SAR imaging, echo model and signal processing knowledge,including the cyclic convolution, Fourier transform, pulse compression, and so on.2. SAR imaging algorithm. RDA algorithm is not only the basic method of theSAR imaging algorithm, but also the efficiency algorithm. Range migration issuesneed to be solved in the imaging process. In addition SAR imaging algorithm includeChirp Scaling algorithm, ωK algorithm and so on. However, these algorithms aredeveloped based on Range Doppler Algorithm. This text combine advantages anddisadvantages of RDA and CSA to design a algorithm which calculate simple andefficiency.3. The inflection of Doppler Ambiguity to range migration correction. When theSAR works in strabismus mode, the maximum Doppler frequency is likely to exceedthe azimuth sampling rate (PRF), it will produce Doppler spectrum aliasing, which have a negative impact on the range migration correction, this text solved thisproblem in a new method.4. Doppler centroid estimation, Doppler chirp rate estimation. Dopplerparameter estimation is an essential step of SAR imaging, when the Dopplerparameter given by the system is not accurate enough, you need to estimate theDoppler parameter from echo data. The Doppler centroid estimation though the phasedifference method. Using an improved image bias algorithm to solve Doppler chirprate estimation, we can reduce the amount of computation while maintaining arelatively high accuracy of estimation5. Motion compensation is performed based on the Doppler parameters. First ofall this text fitting the Doppler frequency and Doppler chirp rate curve, then inaccordance with the mean Doppler center frequency and Doppler chirp rate to matchcompression. At last we solve the motion compensation problem of SAR image basedon compensation function.