Abstract
In marine radar target detection, sea clutter will cause a large number of missed alarms and false alarms, which will affect the accuracy of target detection. In order to suppress sea clutter effectively, a sea clutter suppression and target detection algorithm of marine radar image sequence based on spatio-temporal domain joint filtering is proposed in this paper. The proposed method is to add a sea clutter suppression link before detecting the target. Firstly, the marine radar image sequence is transformed into three-dimensional frequency wavenumber domain by three-dimensional fast Fourier transform (3D-FFT), and then the three-dimensional image spectrum is obtained. According to the fact that the sea clutter spectrum obtained from the image spectrum satisfies the dispersion relation of linear wave theory in the three-dimensional frequency wavenumber domain, a sea clutter model is established. Then, through the established sea clutter model, a spatio-temporal domain joint sea clutter suppressor is designed to filter the image spectrum. After that, the filtered image spectrum is transformed by three-dimensional inverse fast Fourier transform (3D-IFFT) to obtain the image sequence in which sea clutter is suppressed. Finally, target detection is carried out for sea clutter suppressed image sequence. The method is validated by using the real data of X-band marine radar. Compared with the classical Empirical mode decomposition (EMD) method, the improvement of signal-to-noise ratio (SNR) is more obvious, and SNR can be increased by 15.3 db at most. In addition, compared with target detection on original images directly, the proposed method has excellent detection rate and can increase detection rates by at least 8%.
Highlights
College of Physical and Electronic Information, Luoyang Normal University, No 6 Jiqing Road, Abstract: In marine radar target detection, sea clutter will cause a large number of missed alarms and false alarms, which will affect the accuracy of target detection
The methods widely used in X-band marine radar target detection are divided into two categories [1]: constant false alarm rate (CFAR) for target detection and track before detect(TBD) for target tracking
cell-averaging CFAR (CA-CFAR) estimates the gray level of sea clutter by calculating the mean value of the reference unit at both ends of the range unit [3], whereas its detection performance will significantly reduce in multi-target and inhomogeneous environments
Summary
It is always a challenge for marine radar to detect weak target effectively under the background of complex sea clutter. To the time-domain cancellation method, the subspace decomposition method needs to use the Doppler information of radar signal to suppress sea clutter. Inspired by the wave parameter inversion theory of X-band marine radar [65,66,67], aiming at the problem that the existing target detection methods under sea clutter suppression are not applicable to non-coherent marine radars, this paper proposes a sea clutter suppression and target detection algorithm of marine radar image sequence based on spatio-temporal domain joint filtering. A detector is used to detect the target in the processed image sequence This method is a new algorithm that can effectively suppress sea clutter signal by using the amplitude information of radar signal and complete high accuracy target detection.
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