Research On Waveform Design Technique For Stepped Chirp SAR System

The stepped chirp signal with the advantages of "instantaneous narrow-band andsynthetic broadband" can realize high resolution in range dimension as well as reduction ofthe system requirement for volume, power consumption and realization difficulty. However,the synthetic broadband processing of the stepped chirp signal will introduce the gratinglobes inevitably, which are relatively sensitive to system errors. All errors will lead to thedeterioration of the grating lobes and affect the imaging quality. In this paper, the steppedchirp signal system is researched for waveform parameters by the development of the "highresolution micro SAR system", so that it can effectively restrain the level of grating lobes.The main contents include:1. For specific imaging indicators requirement, this paper carried out the waveformparameter design onthe stepped chirp signal radar system. By the analysis of basicrequirement of waveform design, the constraint condition of the waveform parameters ofstepped chirp signal is determined. Meanwhile, the quantitative relationship between thewaveform parameters of the stepped chirp signal and the level of grating lobes is achieved.2. According to the characteristics of stepped chirp signal radar system, the effectcaused by the existing system errors on result of pulse-compression is analyzed. Theintra-pulse and inherent inter-pulse amplitude-phase errorsof the stepped chirp signal radarsystemare analyzed. The effects caused by different errors on the result ofpulse-compression and the different conditions that satisfy the certain requirement on thelevel of grating lobe with different waveform parameters are achieved.3. Forthe system error inprocessing of the high resolution micro SAR system, thequantitative analysis on inherent amplitude-phase error in stepped-frequency system andthe startingdistance error introduced by the sampling window is presented. Besides, theexternal calibration experiment is carried out, providing the data to verify the improvementsituation of the level of grating lobes with different waveform parameters.