| In recent years, the research on Synthetic Aperture Radar (SAR) has made great progress. SARcan greatly improve the azimuth resolution of the radar, and can do area imaging depending on theobserved scene. Meanwhile, in nearly more than ten years, ultra-wideband technology applied inindoor through-wall detection and positioning has drawn more and more people’s attention. Thecharacteristic of ultra-band signal such as high utilization rate of signal spectrum, good signalconfidentiality, not rigorous requirements of the signal shape, high range resolution and capability todetect through obstacles, makes it have irreplaceable advantage in the indoor positioning technology.The technology of ultra-wideband and SAR can be combined into a unique application value of themicrowave sensors, named ultra-wideband synthetic aperture radar (UWB-SAR). UWB-SAR signalscan penetrate through the foliage, surface, to image the goals hiding in obstacles withtwo-dimensional high resolution; in both civil and military areas it has a quite broad applicationprospects. Based on the previous research, referring to literature and periodical at home and abroad,the work of this thesis is given as follows:The first chapter of the thesis briefly states the definition of ultra-wideband signal, UWB-SARdevelopment status at home and abroad, and the UWB signal application in the through-wallpositioning; in the end the generalization of study content in the thesis is explained.The second chapter mainly discusses UWB linear frequency modulation (LFM) signal systemand its application of the SAR imaging algorithm. Briefly introduce the principle of classic SARimaging algorithm, e.g. standard Chirp Scaling (CS) algorithm. The thesis discusses a modified CSimaging algorithm under UWB radar signal condition for signal processing improvement, which canbe applied in broadband LFM signal system. Then the simulation shown the later part demonstratesthe effectiveness of the modified algorithm. Owe to the airborne synthetic aperture radar with UWBLFM signal system, imaging of the object underneath the surface or covered target can be real. Themodified algorithm has practical significance on surveying, mapping and covering the ground surfacethrough obstacles among the detection.The main study object in Chapter3is ultra-wideband through-wall radar. The thesis expoundsthe signal detection in through-wall model and establishes the echo signal model. Double ellipticpositioning method based on look-up table is adopted to locate the target behind the wall. Hypothesisis that the detection area has been known in advance; after searching through the2-d space todetermine time delay quantity and its corresponding position in the area, double elliptic positioning method based on look-up table works. Simulations are shown e.g. the look-up table, double ellipticlocation graph, and the results show that positioning is well done.Chapter4points out a method to estimate the parameters of the wall. Because the generation oflook-up table means positioning system well knows the wall parameters. This ideal hypothesis is notpractical; the error of parameters also can affect the quality of the target positioning. An estimationmethod based on the time delay quantity and the relative position between goals and the antenna isdiscussed, using Newton numerical method to solve the nonlinear equations, and then figuring out theapproximate parameters. Then the simulation results are given, and the estimation is well done.At the end of the thesis, the full text is summarized, and the next study work is list. |
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