Wuhan Radar Academy

Wuhan, China

Wuhan Radar Academy

Wuhan, China
SEARCH FILTERS
Time filter
Source Type

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.


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.


Liu W.,National University of Defense Technology | Xie W.,Wuhan Radar Academy | Liu J.,Xidian University | Wang Y.,Wuhan Radar Academy
IEEE Transactions on Signal Processing | Year: 2014

In this two-part paper, we consider the problem of adaptive multidimensional/multichannel signal detection in Gaussian noise with unknown covariance matrix. The test data (primary data) is assumed as a collection of sample vectors, arranged as the columns of a rectangular data array. The rows and columns of the signal matrix are both assumed to lie in known subspaces, but with unknown coordinates. Due to this feature of the signal structure, we name this kind of signal as the double subspace signal. Part I of this paper focuses on the adaptive detection in homogeneous environments, while Part II deals with the adaptive detection in partially homogeneous environments. Precisely, in this part, we derive the generalized likelihood ratio test (GLRT), Rao test, Wald test, as well as their two-step variations, in homogeneous environments. Three types of spectral norm tests (SNTs) are also introduced. All these detectors are shown to possess the constant false alarm rate (CFAR) property. Moreover, we discuss the differences between them and show how they work. Another contribution is that we investigate various special cases of these detectors. Remarkably, some of them are well-known existing detectors, while some others are still new. At the stage of performance evaluation, conducted by Monte Carlo simulations, both matched and mismatched signals are dealt with. For each case, more than one scenario is considered. © 1991-2012 IEEE.


Liu W.,National University of Defense Technology | Xie W.,Wuhan Radar Academy | Liu J.,Xidian University | Wang Y.,Wuhan Radar Academy
IEEE Transactions on Signal Processing | Year: 2014

In this part of the paper, we continue to study the problem of detecting a double subspace signal in Gaussian noise. Precisely, we address the detection problem in partially homogeneous environments, where the primary and secondary data share the same covariance matrix up to an unknown scaling factor. We derive the generalized likelihood ratio test (GLRT), Rao test, Wald test, and their two-step versions. We also introduce three spectral norm tests (SNTs). All these detectors possess the constant false alarm rate (CFAR) property. Moreover, various kinds of special cases of these detectors are given. At the stage of performance evaluation, we consider two cases. One is the case of no signal mismatch. The other is more general, namely, the case of signal mismatch, including the column-space signal mismatch and row-space signal mismatch. © 1991-2012 IEEE.


Liu W.,National University of Defense Technology | Liu W.,Wuhan Radar Academy | Wang Y.,Wuhan Radar Academy | Xie W.,Wuhan Radar Academy
Signal Processing | Year: 2014

The Fisher information matrix (FIM) is an important tool in signal processing. In this paper, we investigate the FIM with respect to the complex-valued quantities, and show its application in signal processing, such as the design of the Rao and Wald tests, and the derivation of the Cramér-Rao bound for the unbiased estimate. Some examples are also given. © 2013 Published by Elsevier B.V. All rights reserved.


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.


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.


Duan G.Q.,Wuhan Radar Academy | Wang D.W.,Wuhan Radar Academy | Ma X.Y.,Wuhan Radar Academy | Su Y.,National University of Defense Technology
IEEE Geoscience and Remote Sensing Letters | Year: 2010

The 3-D inverse synthetic aperture radar imaging fast maneuvering targets is an active research area in the past decades. Planar antenna arrays are used to avoid the motion compensation algorithms but at the cost of increasing the hardware complexity. In this letter, to reduce the hardware complexity of the imaging system, a wideband multiple-input multiple-output system with two perpendicular linear arrays is suggested. In contrast to the existing 3-D imaging methods with planar antenna arrays, with the proposed method, the lower hardware complexity is achieved by many additive virtual array elements. Simulations based on synthetic data are provided for testing the 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.


Liu W.,National University of Defense Technology | Liu W.,Wuhan Radar Academy | Xie W.,Wuhan Radar Academy | Wang Y.,Wuhan Radar Academy
Eurasip Journal on Advances in Signal Processing | Year: 2013

A Wald test with enhanced selectivity capabilities is proposed in homogeneous environments. At the design stage, we assume that the cell under test contains a noise-like interferer in addition to colored noise and possible signal of interest. We show that the Wald test is equivalent to a recently proposed Rao test. We also observe that this Rao/Wald test possesses constant false alarm rate property in homogeneous environments. © 2013 Liu et al.; licensee Springer.

Loading Wuhan Radar Academy collaborators
Loading Wuhan Radar Academy collaborators