# Fast Moving Target Imaging Algorithm Based on Hough Transform and Third-Order PFT

## Principle of the Proposed Algorithm.

In conventional GMTIm algorithms [8-10], the basic processing steps: firstly, the RCMC is proceeded to compress the energy of the target into a single range gate; secondly, the parameters of the moving target is estimated by using the time-frequency analysis algorithms. Keystone transform is able to correct the range walk without prior knowledge of the Doppler centroid. However, in the case of the fast moving target, Keystone transform is not able to correct the range walk without the Doppler ambiguity number. Therefore, in the case of the fast moving target imaging, the Doppler ambiguity must be taken into consideration.

In this section, a novel algorithm is proposed to focus the moving targets with fast cross-track velocities. After range compression and range curve correction, we utilize Hough transform to estimate the slope of the range walk trajectory of the moving target. With Hough transform, the additional range walk can be accurately corrected regardless of the Doppler ambiguity, and the cross-track velocity can be estimated. Then, we adopt PFT to estimate the second- and third-order Doppler parameters of the moving target. The imaging resolution of the moving target is improved after the third-order phase error compensation, and the motion parameters, including the cross-track acceleration, can be accurately estimated.