Research About Suppression On Azimuth Ambiguity Of SAR

Synthetic Aperture Radar is a sort of microwave imaging system. The image it generatessometimes inevitably has noises on it. Azimuth ambiguity is a kind of unique noise of SAR image,which even forms ghosts, and greatly reduces the application worthiness of a SAR image. So theresearch about suppression on azimuth ambiguity of SAR is very important for the design andapplication of SAR, especially spaceborne SAR.This paper analyzes several crucial parameters of SAR image, like image range,definitionand ambiguity. From the analysis, it gets the cause of azimuth ambiguity as well as it'smeasurement, and introduces how to choose proper Pulse Repeat Frequency. The paper alsoestablishes the model of an echo signal, and analyzes the influence to a chirp signal when samplerate decreases. Basing upon that, it gets the position,phase and attenuation coefficients of azimuthambiguity.From the analysis, it can be seen the noised image approximately is the convolution of clearimage and a blurring filter. So the article proposes a method to suppress the azimuth ambiguityand get the clear image by deconvolving the noised image with the blurring filter, which difficultyis the formation of the blurring filter. In one dimension circumstance, the paper gets the model ofthe blurring filter according to the parameters of azimuth ambiguity, and proves the feasibility ofthis method by simulation. In two dimension circumstance, it analyzes the affections of rangemigration and gives the basic steps to construct a blurring filter. At last the paper discusses theillness of deconvolution and gives the simulation results of image restoration.