Wuhan Electronic Information Institute

Wuhan, China

Wuhan Electronic Information Institute

Wuhan, China
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Liu J.,Xidian University | Zhao H.-Y.,Xidian University | Liu W.,Wuhan Electronic Information Institute | Li H.,Stevens Institute of Technology | Liu H.,Xidian University
Signal Processing | Year: 2017

This paper examines a target detection problem in colored Gaussian disturbance with an unknown covariance matrix. In many classic adaptive detectors, the covariance estimator is formed by using only the training data. This necessitates calculating a new covariance estimator for each cell under test (CUT) during the cell-by-cell target search process. We consider herein an alternative approach that forms the covariance matrix estimate by using both test and training data for detection in homogeneous environments. This approach is computationally much more efficient since the covariance matrix estimator is computed only once and can be applied for target detection at each CUT. Using this estimator, we propose a new detector with two tunable parameters, which includes several existing detectors as special cases. Closed-form expressions for the probabilities of false alarm and detection are derived in the matched and mismatched cases for both non-fluctuating and fluctuating target models. Simulation results reveal that the rejection capability of mismatched signals of the proposed detector can be flexibly controlled by adjusting its tunable parameters. In particular, the proposed detector can achieve the same detection performance as the generalized likelihood ratio test (GLRT) detector derived by Kelly, but has a much lower computational burden. © 2017 Elsevier B.V.


Luo X.,Wuhan Electronic Information Institute | Yu L.,Wuhan Electronic Information Institute | Zhang D.,Wuhan Electronic Information Institute | Wang A.,Wuhan Electronic Information Institute
ICOCN 2016 - 2016 15th International Conference on Optical Communications and Networks | Year: 2016

We present a novel photonic approach based on heterodyne between a multiple-dispersed optical pulse and a continuous optical signal to generate tunable linearly chirped microwave waveform (LCMW) with large time-bandwidth product (TBWP). The carrier frequency of the generated waveform can be changed by tuning the frequency of continuous optical wave outputted from the tunable laser source (TLS),while the TBWP of the LCMW can be changed by optically pumping the linearly chirped fiber Bragg grating (LCFBG) in the dispersive loop with different pumping powers. An extremely large equivalent dispersion will be obtained because of the dispersive loop used in the system, which leads to the generation of LCMW with long temporal duration. The capability of the presented method is verified via numeric simulation. © 2016 IEEE.


Liu J.,Xidian University | Li K.,Wuhan University | Zhang X.,Wuhan Electronic Information Institute | Liu M.,Wuhan Electronic Information Institute | Liu W.,Wuhan Electronic Information Institute
Signal Processing | Year: 2017

This paper investigates the problem of detecting a multichannel signal when subspace signal mismatch occurs. A new detector is proposed, which is obtained by weighting two existing detectors, namely, the subspace-based adaptive matched filter and adaptive subspace detector. The proposed weighted detector has flexibility in controlling its capability of rejection mismatched subspace signals. Specifically, its robustness (or selectivity) for mismatched subspace signals improves as the weight value increases (or decreases). Closed-form expressions for the probabilities of detection and false alarm are derived. The theoretical results are confirmed by Monte Carlo simulations. © 2017 Elsevier B.V.


Dong Y.,Yantai Naval Aeronautical and Astronautical University | Liu M.,Wuhan Electronic Information Institute | Li K.,Wuhan University | Tang Z.,Wuhan Electronic Information Institute | Liu W.,Wuhan Electronic Information Institute
IEEE Signal Processing Letters | Year: 2017

In this letter, we consider the problem of direction detection in deterministic interference and partially homogeneous noise. The target echoes, reflected by a distributed target, all come from the same direction. However, the signal steering vector is only known to lie in a subspace of dimension greater than one. The interference belongs to a subspace linearly independent of the signal subspace. We propose two effective detectors according to the two-step design criteria of the generalized likelihood ratio test and the Wald test. It is shown that the proposed detectors possess the constant false alarm rate property and have better detection performance than their counterparts. © 1994-2012 IEEE.


Li W.,Changsha University | Tong H.,PLA Air Force Aviation University | Li K.,Wuhan University | Yang Y.,Military Representative Office Stationed at 720 Factory | Liu W.,Wuhan Electronic Information Institute
Multidimensional Systems and Signal Processing | Year: 2017

In this paper, we consider the problem of detecting a distributed target in unknown disturbance. The signals reflected by the target are assumed to come from the same direction. However, the exact direction is unknown and yet the signal steering vector lies in a known subspace. The disturbance consists of colored noise and deterministic interference. The interference belongs to a known subspace, linearly independent on the signal subspace. We derive the one-step Wald test and two-step Wald test. Numerical examples show that the proposed detectors can achieve better detection performance than the existing detectors. © 2017 Springer Science+Business Media, LLC


Liu J.,Xidian University | Liu W.,Wuhan Electronic Information Institute | Liu H.,Xidian University
IEEE Transactions on Aerospace and Electronic Systems | Year: 2017

Reed, Mallett, and Brenann (RMB) derived the distribution of the normalized output signal-To-noise ratio (SNR) of an adaptive array, and obtained the RMB rule: The SNR loss is 3 dB when the amount of homogeneous training data used to estimate the noise covariance matrix is approximately twice the dimension of the received signal. Here, we give a new and simpler derivation for this result, based on Bartlett's decomposition of a complex Wishart distribution. © 1965-2011 IEEE.


Wang H.,Wuhan Electronic Information Institute | He M.-H.,Wuhan Electronic Information Institute | Xu J.,Wuhan Electronic Information Institute | Xu D.,Wuhan Electronic Information Institute
Communications in Computer and Information Science | Year: 2012

The recognition of radar emitter signals (RES) is one of the key technologies in electronic countermeasure intelligence system. It's a brand new subject to evaluate the recognition performance scientifically. Formerly most scholars evaluated radar signals recognition methods based on the recognition rate. Aiming at the problem that the evaluation index of recognition effect evaluation of radar signals is single, the paper proposes new evaluation indices. In this paper Analytic Hierarchy Process (AHP) is used to determine the weight of each index, and relevant evaluation model is established for performance evaluation. Simulation result validates that the evaluation model is effective and has certain application prospect. © Springer-Verlag Berlin Heidelberg 2012.


Li J.,Wuhan Electronic Information Institute | Yu L.,Wuhan Electronic Information Institute
Optics Communications | Year: 2016

Photonic generation of arbitrary waveform microwave pulse with tunable carrier frequency and phase based on tunable optoelectronic oscillator (TOEO) and a dual-drive Mach-Zehnder modulator (DDMZM) is proposed. Utilizing the frequency tunability of TOEO, the carrier frequency of the microwave signal can be tuned by adjusting the wavelength of the tunable laser source (TLS) and the tunable range can be as large as tens of GHz. By controlling the signals applied to DDMZM, the generation of arbitrary waveform microwave pulse with tunable phase in the range of -180° to 180° is achieved. The proposed scheme can realize the integration of frequency tuning, phase tuning, pulse modulation and radar transmitted waveform generation in the optical domain, which provides a guarantee of transmitting high-quality microwave signal in radar systems. © 2015 Elsevier B.V.


Sun J.,Wuhan Electronic Information Institute | Yu L.,Wuhan Electronic Information Institute | Zhong Y.,Wuhan Electronic Information Institute
Optics Communications | Year: 2014

A novel single sideband (SSB) radio-over-fiber (ROF) system based on a dual-electrode dual-parallel Mach-Zehnder modulator (DE-DPMZM) is proposed, in which the Mach-Zehnder modulator (MZM) is used to produce a single sideband signal and the dual-parallel structure is used to suppress the third-order intermodulation distortion (IMD3) to improve the spurious-free dynamic range (SFDR) of the ROF system. A theoretical analysis is given and simulation experiment is carried out. The results show that the proposed scheme can improve 25 dB in SFDR which is up to 127.854 dB Hz2/3 compared with the conventional SSB ROF system. In addition, the single sideband modulation can extend the transmission distance of optic signal. © 2014 Elsevier B.V. All rights reserved.


Li J.,Wuhan Electronic Information Institute | Yu L.,Wuhan Electronic Information Institute
ICOCN 2015 - 14th International Conference on Optical Communications and Networks, Proceedings | Year: 2015

A novel photonic approach based on optoelectronic oscillator (OEO) to generate phase-coded pulsed microwave signals with tunable frequency and phase is proposed in the paper. The frequency of the microwave signal can be tuned by changing the wavelength of the optical carrier. The modulating signal is applied to a polarization modulator (PolM) for the generation of the phase-coded optical signal with a tunable phase. The modulated optical signal is sent to the photodetector through an electronically tunable polarizer. By tuning the principal axis of the electronically tunable polarizer, the intensity-modulated signal is obtained, which leads to the generation of the pulsed microwave signal with tunable frequency and phase. The generation of the phase-coded pulsed microwave signals is simulated at MATLAB environment. The approach proposed in this paper has a significant value for phased array beam forming and arrayed signal processing. © 2015 IEEE.

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