Time filter

Source Type

Wuhan, China

Sun K.,Tsinghua University | Meng H.,Tsinghua University | Wang Y.,Wuhan Radar Academy | Wang X.,Tsinghua University
Signal Processing | Year: 2011

In the field of spacetime adaptive processing (STAP), direct data domain (D3) methods avoid non-stationary training data and can effectively suppress the clutter within the test cell. However, this benefit comes at the cost of a reduced system degree of freedom (DOF), which results in performance loss. In this paper, by exploiting the intrinsic sparsity of the spectral distribution, a new direct data domain approach using sparse representation (D3SR) is proposed, which seeks to estimate the high-resolution spacetime spectrum only with the test cell. The simulation of both side-looking and non-side-looking cases has illustrated the effectiveness of the D3SR spectrum estimation using focal underdetermined system solution (FOCUSS) and L1 norm minimization. Then the clutter covariance matrix (CCM) and the corresponding adaptive filter can be effectively obtained. D3SR maintains the full system DOF so that it can achieve better performance of output signal-clutter-ratio (SCR) and minimum detectable velocity (MDV) than current D3 methods, e.g., direct data domain least squares (D3LS). Therefore D3SR can deal with the non-stationary clutter scenario more effectively, where both the discrete interference and range-dependent clutter exists. © 2011 Elsevier B.V. All rights reserved.

Zenghui Z.,National University of Defense Technology | Jubo Z.,National University of Defense Technology | Yongliang W.,Wuhan Radar Academy
IET Radar, Sonar and Navigation | Year: 2012

Space-time adaptive processing (STAP) is an advanced technique for airborne radar to mitigate clutter and detect moving targets effectively. Based on adaptive radar theory, the degrees-of-freedom of a STAP processor should be larger than that of a clutter. In this study, the local degrees-of-freedom (LDOF) of clutter for reduced-dimensional STAP (RD-STAP) methods with subarray configurations are studied. The LDOF formulas are proposed and verified by simulations. With these formulas, the LDOFs of clutter will collapse under certain radar configurations, which are favourable for clutter mitigation. Therefore these formulas could be used as guidance for STAP radar to choose appropriate system parameters and processing methods. © 2012 The Institution of Engineering and Technology.

Wang D.-W.,Wuhan Radar Academy | Ma X.-Y.,Wuhan Radar Academy | Chen A.-L.,The Academy of Management | Su Y.,National University of Defense Technology
IEEE Transactions on Image Processing | Year: 2010

Imaging a fast maneuvering target has been an active research area in past decades. Usually, an array antenna with multiple elements is implemented to avoid the motion compensations involved in the Inverse synthetic aperture radar (ISAR) imaging. Nevertheless, there is a price dilemma due to the high level of hardware complexity compared to complex algorithm implemented in the ISAR imaging system with only one antenna. In this paper, a wideband multiple-input multiple-output (MIMO) radar system with two distributed arrays is proposed to reduce the hardware complexity of the system. Furthermore, the system model, the equivalent array production method and the imaging procedure are presented. As compared with the classical real aperture radar (RAR) imaging system, there is a very important contribution in our method that the lower hardware complexity can be involved in the imaging system since many additive virtual array elements can be obtained. Numerical simulations are provided for testing our system and imaging method. © 2010 IEEE.

Wang D.-W.,Wuhan Radar Academy | Ma X.-Y.,Wuhan Radar Academy | Su Y.,National University of Defense Technology
IEEE Transactions on Image Processing | Year: 2010

This paper presents a system model and method for the 2-D imaging application via a narrowband multiple-input multiple-output (MIMO) radar system with two perpendicular linear arrays. Furthermore, the imaging formulation for our method is developed through a Fourier integral processing, and the parameters of antenna array including the cross-range resolution, required size, and sampling interval are also examined. Different from the spatial sequential procedure sampling the scattered echoes during multiple snapshot illuminations in inverse synthetic aperture radar (ISAR) imaging, the proposed method utilizes a spatial parallel procedure to sample the scattered echoes during a single snapshot illumination. Consequently, the complex motion compensation in ISAR imaging can be avoided. Moreover, in our array configuration, multiple narrowband spectrum-shared waveforms coded with orthogonal polyphase sequences are employed. The mainlobes of the compressed echoes from the different filter band could be located in the same range bin, and thus, the range alignment in classical ISAR imaging is not necessary. Numerical simulations based on synthetic data are provided for testing our proposed method. © 2010 IEEE.

Liu W.,National University of Defense Technology | Xie W.,Wuhan Radar Academy | Wang Y.,Wuhan Radar Academy
IEEE Signal Processing Letters | Year: 2013

In this letter, we consider the problem of detecting a distributed target with unknown signal steering in the Gaussian noise. We derive the Rao and Wald tests. It is found that the Rao test coincides with the so-called modified two-step generalized likelihood ratio test (M2S-GLRT), while the Wald test is equivalent to the plain two-step GLRT (2S-GLRT). We also give some intuitive interpretations about the Rao and Wald tests, as well as other existing detectors. © 2013 IEEE.

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