| Synthetic aperture radar (SAR), which is a kind of microwave imaging radar, wasdeveloped nearly60years. Because the SAR detects the targets by launchingelectromagnetic wave to the target area and receiving the echo from it, it has manyexcellent properties compared with traditional infrared and optical imaging method.Electromagnetic waves can penetrate clouds, rain, snow, fog, etc., so the SAR works inthese complex weather conditions; Electromagnetic waves can penetrate the vegetation,so the SAR can detect enemy camouflage of military equipment; because the SAR is akind of active radar imaging by echo of electromagnetic wave, it works without lightand heat, so it can work all day and night or in the polar area. These superior propertiesmake the synthetic aperture radar become an important tool for civil and militaryreconnaissance and surveying and mapping. Because of these, the thesis studied thesynthetic aperture radar imaging algorithms. The main work done is as follows:1. The airborne SAR imaging algorithm is studied. The research is mainly focusedon the range-doppler algorithm; the range-doppler algorithms for side-looking modeSAR, squint mode SAR are deduced. The algorithms are verified by MATLAB.2. The missile-borne SAR imaging algorithm is studied. Similarities anddifferences between missile-borne and airborne SAR imaging algorithm are analyzed.Series inversion is used to deduce the two-dimensional frequency domain expressionsof the echo of side-looking descending branch (velocity and acceleration exist both inazimuth and vertical dimension) SAR and side-looking three-dimensional acceleration(azimuth, horizontal dimension, and vertical dimension) SAR. The imaging algorithmsare given based on the expressions. The imaging algorithms are indicated and verifiedby MATLAB.3. Non-linear frequency modulated signal SAR imaging is studied. The property ofnon-linear frequency modulated signal and its generation and whether regular imagingalgorithm apply to non-linear frequency modulated signal SAR are particularly studied.MATLAB is used to simulate non-linear signal generation, non-linear signal SAR echogeneration, non-linear signal SAR imaging. 4. Advantages and disadvantages of C++and MATLAB combined programmingmethods are analyzed. Based on the aforementioned algorithm research, Matcomsoftware is used to realize combined programming of Visual C++and MATLAB,completing design of SAR imaging simulation software. Applying powerful visualprogramming ability of Visual C++and ultrastrong computing ability of MATLAB,such simulation software possesses good portability, since it does not depend onMATLAB environment as common C++and MATLAB combined programmingmethods do. |
