Research On LFM Errors And LFM Signal Generating Technology In SAR

Synthetic Aperture Radar (SAR) gains a high-resolution radar image by compressing the Doppler echo in azimuth direction and the linear frequency modulation (LFM) signal in range direction. The quality of LFM signal has a direct influence on the impulse response function of SAR, and thus on the quality of radar image, so the design of LFM signal generator is one of the keys in SAR system design.The thesis briefly introduces fundamental SAR operational principle and LFM signal theory firstly, and systemically analyses the effects on SAR impulse response function caused by LFM signal errors on the basis of traditional binate echo theory. In addition, the thesis also simulates the side label level, main label width and integration side label ratio-the critical quality indexes, and then draws out relation formulas between the indexes and the errors providing theory reference for practical system design.The other key issue of the thesis is research on LFM generating technology. A novel design method for waveform storage LFM signal generator using Field Programmable Gate Array (FPGA) is proposed, hardware realized and tested, the error of circuit components and testing results are also analyzed. Finally, some improving proposals are given out at the end of the thesis.The results show that waveform storage LFM signal generator using FPGA is a flexible, integrated, reliable and multi-functional LFM generator, it is very practical to generate LFM signal with no more than 40M band width, and also novel in some degree compared with other LFM digital synthesizing method.