Fast algorithm for estimating ocean surface velocity and coherence time

This paper deals with the estimation of celerity and coherence time using array of equispaced sensors for observing the ocean surface. A fast algorithm based on array processing or spatial analysis is proposed. Initially, two-antenna synthetic aperture radars (SAR) system are used in order to obtain two images of the same surface of the ocean afterwards the analysis of these images by using the signal processing or spectral analysis leads to estimate phase difference between the images and finally the mean short-term Doppler shift of the scattering from the ocean surface is estimated on pixel by pixel basis. To improve velocity and time coherence estimation the multiple antenna system is introduced in SAR system. Indeed, the use of more than two-antennas allows to develop statistical methods or multidimensional signal processing algorithms. Interesting studies, in which the blind maximum likelihood algorithms are used, have been published. Its performance is proved to be more accurate than the two-antenna SAR system based methods. The proposed algorithm is based on the second order statistics of the received data. Both the correlation and the coherence matrices are used for estimating the noise power, the spatial correlation matrix of the speckle and the coherence time of the ocean surface.