A method for detecting small targets in sea surface based on Ridges-Radon Transform

Aiming at the technical difficulty of radar to detect the small targets embedded in the sea clutter, a frame smoothing dual-feature detection method based on Ridges-Radon transform was proposed. Firstly, the block whitening method is used to suppress the sea clutter. According to the different energy distribution characteristics of the sea clutter and target cell in the time-frequency plane, the Radon transform is performed on the time-frequency ridge so as to extract the peak and bandwidth features. Considering that the number of coherent pulses used by the actual radar is usually less (64 or less in most cases), it is easy to lead to the instability of the features and affect the separability of the sea clutter and targets. Therefore, the frame smoothing method which is based on the comprehensive application of multi-frame scanning historical data and current frame data is carried out to enhance the separability. Finally, the convex hull classification algorithm is used to perform fusion detection in the dual feature plane. It is verified by the measured data of level 2 and level 4 sea conditions that, under the same parameters, the proposed detection method has better detection performance than the existing detection method based on three time-frequency features、fractal feature and the CFAR detection method in frequency domain.