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Zhang W.,Missile Institute | Tong C.-M.,Missile Institute | Tong C.-M.,Nanjing Southeast University | Zhang Q.,Institute of Telecommunication Engineering
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2011

Aiming at extracting the time-varying micro-Doppler feature of the vibrating target in ground clutter environment, the method of micro-Doppler extraction based on dual-channel ATI technique and Radon transform is presented. The ATI technique is utilized to suppress ground clutter and obtain the interferometric signal of the vibrating target, which is presented as a straight line along the azimuth direction in the range-compressed data domain. The Radon transform is utilized to detect the weak straight line and find out which range cell it locates at. And the mathematical expressions of micro-Doppler with different vibrating directions are derived and discussed in detail. Compared with the single-channel situation, it is no need to compensate for the Doppler shift caused by the radar's translation, and the target vibrating along the azimuth direction could be effectively detected, whose micro-Doppler presents remarkably nonperiodic feature. Simulated results verify the accuracy and availability of the proposed method.


Lei Q.,Institute of Telecommunication Engineering | Li H.,Institute of Telecommunication Engineering | Zhang Q.,Institute of Telecommunication Engineering | Zhu F.,Institute of Telecommunication Engineering | Wen X.,Unit 93285 of PLA
2010 9th International Symposium on Antennas Propagation and EM Theory, ISAPE 2010 | Year: 2010

In the face of sparse aperture data imaging, a method for high resolution radar imaging based on compressed sensing using sparse stepped-frequency signal is proposed in this letter. In the signal stretching process, high resolution target echo can be acquired through second sample for the coarse-resolution range profile. Based on the sparsity of the signal in the spectrogram, we can construct a reasonable partial fourier sparse basis matrix to realize the sparsity of radar data. Then, the high-resolution range profile information is recovered by using the Orthogonal Matching Pursuit (OMP) algorithm, and the high resolution target imaging can be gained whose target sidelobe is suppressed efficiently. Finally, the results with simulation data validate the feasibility and superiority of the approach. ©2010 IEEE.


Zhu X.-P.,Institute of Telecommunication Engineering | Zhang Q.,Institute of Telecommunication Engineering | Zhang Q.,Fudan University | Li H.-W.,Institute of Telecommunication Engineering
Yuhang Xuebao/Journal of Astronautics | Year: 2011

A method called Polar Format Algorithm(PFA) suitable for the Bistatic-ISAR system is analyzed, the coordinate transformation from polar coordinate to rectangular coordinate is achieved by linear interpolation in range dimension and non-linear interpolation in azimuth dimension. Considering the complexity in interpolation, an improved PFA is proposed by using Chirp-Z transformation to replace the range dimension interpolation, thus reducing computational complexity greatly and obtaining the same effect as interpolation. Simulations of scatter points have demonstrated the validity of the proposed improved algorithm.


Zhu F.,Institute of Telecommunication Engineering | Zhang Q.,Institute of Telecommunication Engineering | Zhang Q.,Fudan University | Lei Q.,Institute of Telecommunication Engineering | Luo Y.,Institute of Telecommunication Engineering
IEEE Sensors Journal | Year: 2011

This paper introduces a novel reconstruction method of high-resolution range profile (HRRP) using sparse frequency-stepped chirp signal (FSCS). In the method, Compressed Sensing (CS) theory is utilized to reconstruct the moving target's HRRP. With this method even if the subpulses number of FSCS is incomplete, the HRRP can still be reconstructed successfully, and the final reconstructed ISAR image is clear enough for identification and classification of the target. Furthermore, the effect of noise is also analyzed by corrupting the data via an uncorrelated additive white Gaussian process. © 2011 IEEE.


Zhu R.-F.,Institute of Telecommunication Engineering | Zhu X.-P.,Institute of Telecommunication Engineering | Zhang Q.,Institute of Telecommunication Engineering | Zhang Q.,Fudan University
Yuhang Xuebao/Journal of Astronautics | Year: 2012

A method is proposed for solving the problem when using Frequency Modulation Continuous Wave(FMCW) in Bi-static ISAR system. Considering coupling terms induced by using FMCW signal, the Discrete Polynomial Phase Transform(DPT) is used to estimate the combined component, then the phases of echo signal are compensated by using compensation functions to eliminate the fixed frequency offset caused by first coupling term and main-lobe expansion induced by second coupling term. The Range Doppler algorithm is used to attain clear target's image. At last, the validity of the proposed compensation algorithm is validated by simulation and focused image is obtained.


Deng D.H.,Institute of Telecommunication Engineering | He J.,Institute of Telecommunication Engineering | Wang M.,Institute of Telecommunication Engineering | Zhang Q.,Institute of Telecommunication Engineering | Bai P.,AFEU
Proceedings of 2011 IEEE CIE International Conference on Radar, RADAR 2011 | Year: 2011

If the target or any structure on the target undergoes micro-motion dynamics, such as mechanical vibrations or rotations, it will induce Doppler frequency modulation on the returned signal that generates sidebands about the target's Doppler frequency, which is referred to as the micro-Doppler effect. The micro-Doppler signatures enable certain properties of the target to be determined that may be used for target recognition. In this paper, taking the Micro-Doppler effect caused by the rotation of target in Bi-static inverse synthetic aperture radar (Bi-ISAR) system as example, a novel extraction method of the micro-motion feature is presented. With the proposed method, the micro-motion parameters of the target can be detected rapidly from the spectrogram and the computational efficiency can be enhanced compared with that of the modified extended Hough transform. A computer simulation is given to illustrate the effectiveness of the proposed method. © 2011 IEEE.


Zhu F.,Institute of Telecommunication Engineering | Zhang Q.,Institute of Telecommunication Engineering | Yan J.-B.,Institute of Telecommunication Engineering | Gu F.F.,Institute of Telecommunication Engineering | Zhu M.,Institute of Telecommunication Engineering
Progress in Electromagnetics Research Symposium | Year: 2012

In this paper, a SAR imagery compressing and reconstruction method based on Compressed Sensing (CS) theory is proposed. In the method, the SAR imagery can be divided to several sub-imageries firstly. Discrete Wavelet Transform (DWT) can be utilized to make SAR imagery sparse and the random Gauss matrix after approximate Orthogonal-matrix and Right- matrix (QR) decomposition can be employed to complete the low-dimension measurement for sparse results. For reconstructing SAR imagery, a modified Orthogonal Matching Pursuit (OMP) algorithm is proposed to perform better. On condition of the same reconstruction precision, the search burden is reduced and convergency speed is enhanced by using the proposed modified OMP algorithm. At the same time, the sparsity estimation can be avoided. Furthermore, some processing containing IDWT can be engaged to achieve the final reconstructed SAR imagery. The effectiveness of the proposed method can be validated by simulation results.


Ye Z.,Institute of Telecommunication Engineering | Zhang B.-N.,Institute of Telecommunication Engineering | Guo D.-X.,Institute of Telecommunication Engineering
Yuhang Xuebao/Journal of Astronautics | Year: 2011

FFT based frequency estimation algorithms such as Rife and Quinn do not have robust performance in the presence of fluctuation of signal frequency. Good performance can be made at some frequencies. But it is deteriorated seriously at other frequencies. A new frequency estimation algorithm based on trigonometric interpolation is proposed here to solve this problem, and can be applied for satellite communication at low signal-noise ratio. Crude frequency estimation is made by FFT first. Then the trigonometric interpolation algorithm is used to improve the estimation accuracy. Finally, the result is adjusted to get unbiased estimation. Simulations indicate that the algorithm achieves accurate and robust results at all frequencies. MSE of the algorithm closely approaches to CRB at any frequency. Furthermore, the algorithm has low threshold of signal-noised ratio. Compared with time-domain algorithms, the proposed algorithm needs simpler operation, and the same performance requirement can been easily implemented.


Ye Z.,Institute of Telecommunication Engineering | Zhang B.-N.,Institute of Telecommunication Engineering | Pan X.-F.,Institute of Telecommunication Engineering
Xitong Fangzhen Xuebao / Journal of System Simulation | Year: 2012

Only crude results can be acquired when estimating frequency and phase by FFT directly, because of its barrier effect. Extra operation such as interpolation must be made to get accurate result from FFT. A frequency and phase estimation algorithm based on difference of FFT's phase has been proposed by references [1] and [2]. The barrier effect is eliminated and accurate estimation is acquired by this method. However, its performance depends on frequency of the signal to be estimated. Though the results are quite satisfying for some frequencies, other ones would lead to seriously deteriorated results. This problem is analyzed here in detail and new modified method is proposed to solve it. Simulations suggest that the modified algorithm has robust performance with the frequency moving at the entire estimating range. Furthermore, the modified algorithm requires simple operation and can be easily implemented. © Copyright.


Zhu F.,Institute of Telecommunication Engineering | Zhang Q.,Institute of Telecommunication Engineering | Gu F.-F.,Institute of Telecommunication Engineering | Li K.-M.,Institute of Telecommunication Engineering
Yuhang Xuebao/Journal of Astronautics | Year: 2012

Combined with sparse SIMO radar array in space domain, the two dimensional sparsity model for radar imaging with high resolution is established in this paper with frequency-stepped chirp signal (FSCS). First, a velocity estimation method for moving targets is introduced for this model based on image entropy criteria, and the accurate velocity estimation is implemented by simple zero-padding for low dimensional data. Second, in combination of the Compressed Sensing (CS) theory, the effective measurement matrix, the sparsity transform matrix and the reconstruction algorithm are designed to obtain the high-resolution range profile (HRRP), then a phase remain character based new imaging method is proposed for SIMO high-resolution sparse radar by two dimensional sparsity processing in the frequency and the space domains. The model can reduce not only the number of sub-pulses in FSCS burst, but also reduce the number of receivers of SIMO high-resolution radar, in the meanwhile, the high quality HRRP and two dimensional images of targets can be achieved. Effectiveness and robustness of the method are proved by the simulation results.

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