A method for detecting weak and small targets in sea clutter background based on multi-scale directed lyapunov exponents

Abstract

The invention provides a weak and small target detection method under the sea clutter background based on the "multi-scale directed Lyapunov index". Hilbert transformation is performed on the radar echo data and the instantaneous phase angle theta is solved, first-order and second-order differential theta<.> and theta<..> are calculated and a state space matrix [theta, theta<.>, theta<..>] is constructed; and the state space is divided into sub-matrixes having no mutual intersection according to a certain scale, the covariance matrix of each sub-matrix is solved and eigenvalue decomposition isperformed, the main eigenvalue sigma<ip> and the eigenvector v<ip> are extracted, the inclined angle psi between the adjacent covariance matrix main eigenvectors is calculated, and (sigma<ip>, psi) is defined as the directed Lyapunov index of the radar echo data. The (sigma<ip>, psi) obtained according to different division length forms the multi-scale directed Lyapunov index, and the weak and small target under the sea clutter background can be accurately detected by the fluctuation characteristics of the index.

Description

technical field [0001] The invention belongs to the technical field of target detection under the sea clutter background, and is a target detection method based on state space reconstruction and nonlinear signal processing, in particular to a weak and small target under the sea clutter background based on multi-scale directed Lyapunov exponents Detection method. Background technique [0002] The research on weak and small target detection methods in the background of sea clutter has a long history, and it has been used to detect floating objects on the sea surface (ice floes, small ships and aircraft wrecks, etc.) in the civilian field, providing technical support for civil ship navigation and maritime search and rescue. In the military field, this method is used to detect ships with stealth characteristics at sea, submarine periscopes, and aircraft flying close to the sea surface. The traditional method is to regard sea clutter as a complex stationary random process. Obser...

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Problems solved by technology

The classic solution is to dynamically track the statistical characteristics of radar echoes, and process them in segments according to the principle of similar characteristics, which solves some problems at the engineering level. However, with the improvement of sea conditions, the radar echo data The segmentation is getting shorter and shorter, and finally there is no essential difference with the short-term observation situation, resulting in a high false alarm probability and a low detection probability when detecting weak targets. Therefore, the signal processing method based on statistical characteristics Under the condition of high sea state, it can no longer meet the needs of engineering, and it is necessary to find another way to solve this problem from the level of theory and method

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