Weak Target Detection within the Nonhomogeneous Ionospheric Clutter Background of HFSWR Based on STAP

Abstract

High Frequency Surface Wave Radar (HFSWR) can perform the functions of ocean environment monitoring, target detection, and target tracking over the horizon. However, its system's performance is always limited by the severe ionospheric clutter environment, especially by the nonhomogeneous component. The nonhomogeneous ionospheric clutter generally can cover a few Doppler shift units and a few angle units. Consequently, weak targets masked by the nonhomogeneous ionospheric clutter are difficult to be detected. In this paper, a novel algorithm based on angle-Doppler joint eigenvector which considers the angle-Doppler map of radar echoes is adopted to analyze the characteristics of the nonhomogeneous ionospheric clutter. Given the measured data set, we first investigate the correlation between the signal of interest (SOI) and the nonhomogeneous ionospheric clutter and then the correlation between the nonhomogeneous ionospheric clutters in different two ranges. Finally, a new strategy of training data selection is proposed to improve the joint domain localised (JDL) algorithm. Simulation results show that the improved-JDL algorithm is effective and the performance of weak target detection within nonhomogeneous ionospheric clutter is improved.

Ionospheric Clutter Model for HF Sky-Wave Path Propagation with an FMCW Source

“…where → is the Fourier coefficient of the ionospheric irregularities, is the diameter of the scattering area varied from 0 to Δ , and → is the wavenumber of the ionospheric irregularities. The field in (1) can be transformed to the time domain by applying inverse Fourier transform (see (7) in [18]):…”

“…Thus it is necessary to develop a mathematic model to quantify the impact of the ionosphere. Many investigations have been made on the characterization of ionospheric clutter and suppression of ionospheric clutter [6][7][8][9][10][11]. These ionospheric clutter mitigating techniques include many complicated adaptive signal processing algorithms or additional antennas.…”

An Improved Oblique Projection Method for Sea Clutter Suppression in Shipborne HFSWR

“…a(ϕ) = e j2π( d λ ) cos(ϕ)[0,1,...,N −1] T (15) where E N is the N × N identity matrix, N is the number of receiving sensors, ϕ 0 is the azimuth of the first-order sea clutter in the frequency f 0 , and a(ϕ) is the spatial steering vector. The test statistic of the IOP algorithm is similar to (10) and can be constructed by…”

“…However, its applied conditions are the correlation or homogeneity of the LPR over range cells [13], [15]. To validate the performance of the IOP algorithm, the correlation of the LPR in the range dimension is analyzed based on real clutter data.…”

A Geometric Barycenter-Based Clutter Suppression Method for Ship Detection in HF Mixed-Mode Surface Wave Radar

“…The power-selected training (PST) algorithm [15] chooses the samples with the strong clutter power to deepen the clutter notch. The similarity detector (SD) algorithm [16][17][18][19] selects the samples with waveforms that are similar to the CUT. Recently, the information geometry-based SD algorithm has drawn more attentions on covariance estimation and target detection processing [20][21][22][23][24].…”