The Research Of Imaging Algorithm And Anti-jamming On Spotlight SAR

Currently Synthetic Aperture Radar (SAR) plays an important role in the field of radarimaging. Most researchers are working on stripmap imaging mode, while few persons studyspotlight SAR. Small scenes especially including a target are imaged by spotlight SAR.Echo data received are processed respectively by RD algorithm, S-RD algorithm and FSalgorithm. Among many algorithms, RD and S-RD algorithms are simple to implement. FSalgorithm is a highly focused algorithm, which has done a complete compensation andconsidered the variability from the distance migration. And it also has shortcomings, such aslong process, time-consuming, which is not suitable for real-time system.When the synthetic aperture is long, the azimuth doppler band is very wide, whichincreases the pulse repetition frequency. When the PRF is high, the volume of echo data isvery large, which increases the data processing time. This paper proposes an improved RDalgorithm. It splits data into two parts by different doppler frequency. And every part data isprocessed respectively by RD algorithm. Finally the data are coherently added to image thescene. The result shows that improved RD algorithm can reduce the impact of aliasing image.On the anti-jamming, this paper mainly studies deception jamming and the chaff cloud.For the similarity of the jam echo data and the signal data, waveform change of the signal isused to confront deception jamming, which includes random phase and changing chirp rate.Finally it shows that the methods can achieve the purpose within a certain SNR range. On thechaff jamming, this paper adds the echo of chaff cloud to the imaging model. Changing therange resolution and polarized wave are discussed to confront the jamming. Finally it showsthat, to some extent, both the methods can reduce the interference of the chaff cloud.