Higher-order polynomial based NCS algorithm for broadband and wide swath synthetic aperture sonar

This paper presents an advanced nonlinear chirp scaling (NCS) algorithm based on a higher-order polynomial for the imaging of the broadband and wide swath synthetic aperture sonar. The first key of the proposed algorithm is the consideration of the sixth-order term with respect to the frequency range in the approximation of the two-dimensional frequency spectrum, which leads to an increased broadband adaptation. The other key is that the third-order range-variant property with respect to the equivalent chirp rate is taken into account to improve the adaptation to the wide swath element of the proposed algorithm. The proposed algorithm is highly efficient because it requires only complex multiplies and Fourier transforms to implement. The results of error analysis and simulation show the effectiveness of the proposed algorithm.