| Synthetic Aperture Radar (SAR) is a kind of high resolution imaging radar, which can work in allweather conditions day-and-night. Classical imaging modes of SAR include spotlight, stripmap andscanning, Circular-scanning SAR is a new radar imaging mode,which developed in recent years. Theimaging quality of SAR is closely related to accuracy of the system parameters, especially the speedof radar platform is one of the most important parameters. In this paper, a new estimation method forspeed of the radar platform and antenna scanning angle is put forward by the characteristics of theCircular-scanning SAR imaging mode. The imaging quality of the Circular-scanning SAR system isobviously improved by using the parameters which are estimated by the new method. The maincontents of this paper are summarized as follows:The first chapter introduces a brief overview development history of the SAR technology,discusses the current situations of SAR technology and future development trendency, this paperbriefly introduces four modes of the SAR imaging, and pointed out the main research contents of thepaper.The second chapter studies the method of doppler center frequency estimation. Doppler centerfrequency is a necessary condition for doppler velocity estimation, this chapter introduces mainthought of doppler center frequency estimation from the radar echo signal,which is based on thedoppler center frequency definition and physical meaning.The last analysis five estimation methods ofdoppler center specifically, and illustrates the concrete implementation steps.The third chapter mainly studies the doppler velocimetry technology. This paper deducescalculation formula of load machine speed calculation formula from the doppler center frequencycalculation formula, we can estimate three-dimensional component of the carrier aircraft speedthrough the radar launching three beams to the ground at the same time. This chapter puts forward aestimation method to search the velocity of aircraft and real azimuth by the least square method,whichthe azimuth is error. Finally, the feasibility of the method is verified by simulation.The forth Chapter introduces the principle of the Circular-scanning SAR and the geometricdistortion correction briefly,and studies the effect of parameters to the geometric distortioncorrection.This paper founds a velocimetry model for the Circular-scanning SAR,which applied theDoppler velocimetry principle in the Circular-scanning SAR. Comparing of the results of SARimaging simulation,we can get that the parameters from doppler velocimetry make Circular-scanning SAR imaging quality greatly be improved.In Chapter5,the whole work is concluded and the future work is pointed out. |
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