The Study Of FMCW SAR Imaging Algorithms And Ambiguity Analysis

Continuous Wave radar is getting more and more attention because of its light-weight,small-cubage, high-reliability etc. advantages. Frequency Modulated Continuous WaveSynthetic Aperture Radar (FMCW SAR), which combines Continuous Wave radartechnique and SAR technique, can achieve high-resolution radar imaging, and at the sametime satisfies the demand of small,light-weight and cost-effective. So FMCW SAR isgradualy becoming a hotspot which human focus on.Compared with Pulse SAR, FMCW SAR is different in translating signals, and so thedifferences in return signal model,imaging processing and ambiguity representation etc. arecaused. Discussing the different characterastics of Pulse SAR and FMCW SAR, andresearching the proper imaging processing techniques and methods of FMCW SAR arevery important.At fist this thesis discusses the basic principles of FMCW SAR. It dicusses the principlehow FMCW SAR improves range resolution in FMCW ranging, and the principle how FMCW SARimproves azimuth resolution and implements synthetic aperture processing in synthetic aperture andfrequency spectrum analysis. Based on that it gives the return signal model of FMCW SAR system.Based on Pulse SAR's basic imaging algorithm—R-D algorithm andω-k algorithm, itresearches the proper imaging algorithms for FMCW SAR system. Because FMCW SARsystem has Doppler error effect, it detailedly discusses the Doppler error's effect to FMCWSAR imaging system, and gives the compensation method. According to the particularcharacterastics of FMCW SAR imaging, it gives the proper modified R-D andω-kalgorithms for FMCW SAR imaging system. It detailedly discusses algorithms' principle,gives the imaging system flow chart, and simulates the modified R-D andω-k algorithms.Based on that it compares and discusses the difference of Pulse SAR imaging algorithmsand FMCW SAR imaging algorithms.According to the ambiguity problem in FMCW SAR system, it discusses FMCW SARrange ambiguity's form and the difference from Pulse SAR range ambiguity in return signalwindow,system parameters design,range ambiguity ratio etc. Based on that, this thesisproposes a method which uses code-division to restrain range ambiguity, and givesdetailedly principles and simulation results, which proves the correction of this method. At last it discusses the azimuth ambiguity of FMCW SAR, and concludes that FMCW SARsystem is a ultimate form of Pulse SAR.