PROJECT TITLE :

Scene size limits for polar format algorithm

ABSTRACT:

Synthetic aperture radar (SAR) is a type of remote sensing where coherent radar echoes transmitted from a moving platform are processed to create a picture of a scene, typically on the ground. There are several algorithms that have been developed with varying levels of complexity and accuracy. In applications with giant scene size requirements, the choice of image formation algorithm is important. Actual imaging algorithms like the back-projection algorithm (BPA) can kind giant images without errors, but they are computationally expensive. Another well-known algorithm is that the polar format algorithm (PFA), which is significantly faster than BPA, but it uses approximations that cause image errors in large scenes. In this paper, we have a tendency to evaluate the scene size limitations of the PFA in terms of image defocus. This is often caused by residual quadratic part errors that arise due to approximations within the algorithm. We derive this residual quadratic part error employing a Taylor series expansion in the slow time dimension. Then, we tend to derive simplified expressions for image defocus for two flight methods: circular and linear. We additionally use the Taylor series growth to derive correct corrections for image distortion caused by PFA. These distortion corrections are employed in conjunction with the residual quadratic phase errors to derive correct scene size limitations that are notably completely different from the circular regions of focus determined in earlier works.