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Micro-Doppler feature extraction of micro-rotor UAV under the background of low SNR 被引量:4
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作者 HE Weikun SUN Jingbo +1 位作者 ZHANG Xinyun LIU Zhenming 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2022年第6期1127-1139,共13页
Micro-Doppler feature extraction of unmanned aerial vehicles(UAVs)is important for their identification and classification.Noise and the motion state of the UAV are the main factors that may affect feature extraction ... Micro-Doppler feature extraction of unmanned aerial vehicles(UAVs)is important for their identification and classification.Noise and the motion state of the UAV are the main factors that may affect feature extraction and estimation precision of the micro-motion parameters.The spectrum of UAV echoes is reconstructed to strengthen the micro-motion feature and reduce the influence of the noise on the condition of low signal to noise ratio(SNR).Then considering the rotor rate variance of UAV in the complex motion state,the cepstrum method is improved to extract the rotation rate of the UAV,and the blade length can be intensively estimated.The experiment results for the simulation data and measured data show that the reconstruction of the spectrum for the UAV echoes is helpful and the relative mean square root error of the rotating speed and blade length estimated by the proposed method can be improved.However,the computation complexity is higher and the heavier computation burden is required. 展开更多
关键词 micro-rotor unmanned aerial vehicle(UAV) low signal to noise ratio(SNR) MICRO-DOPPLER feature extraction parameter estimation
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Blind parameter estimation of pseudo-random binary code-linear frequency modulation signal based on Duffing oscillator at low SNR 被引量:1
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作者 Ke Wang Xiaopeng Yan† +2 位作者 Ze Li Xinhong Hao Honghai Yu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第5期312-319,共8页
Conventional parameter estimation methods for pseudo-random binary code-linear frequency modulation(PRBC-LFM)signals require prior knowledge,are computationally complex,and exhibit poor performance at low signal-to-no... Conventional parameter estimation methods for pseudo-random binary code-linear frequency modulation(PRBC-LFM)signals require prior knowledge,are computationally complex,and exhibit poor performance at low signal-to-noise ratios(SNRs).To overcome these problems,a blind parameter estimation method based on a Duffing oscillator array is proposed.A new relationship formula among the state of the Duffing oscillator,the pseudo-random sequence of the PRBC-LFM signal,and the frequency difference between the PRBC-LFM signal and the periodic driving force signal of the Duffing oscillator is derived,providing the theoretical basis for blind parameter estimation.Methods based on amplitude method,short-time Fourier transform method,and power spectrum entropy method are used to binarize the output of the Duffing oscillator array,and their performance is compared.The pseudo-random sequence is estimated using Duffing oscillator array synchronization,and the carrier frequency parameters are obtained by the relational expressions and characteristics of the difference frequency.Simulation results show that this blind estimation method overcomes limitations in prior knowledge and maintains good parameter estimation performance up to an SNR of-35 dB. 展开更多
关键词 Duffing oscillator pseudo-random binary code-linear frequency modulation(PRBC-LFM)signal blind parameter estimation low signal-to-noise ratio(SNR)
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Single-Channel Speech Enhancement Based on Improved Frame-Iterative Spectral Subtraction in the Modulation Domain 被引量:1
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作者 Chao Li Ting Jiang Sheng Wu 《China Communications》 SCIE CSCD 2021年第9期100-115,共16页
Aiming at the problem of music noise introduced by classical spectral subtraction,a shorttime modulation domain(STM)spectral subtraction method has been successfully applied for singlechannel speech enhancement.Howeve... Aiming at the problem of music noise introduced by classical spectral subtraction,a shorttime modulation domain(STM)spectral subtraction method has been successfully applied for singlechannel speech enhancement.However,due to the inaccurate voice activity detection(VAD),the residual music noise and enhanced performance still need to be further improved,especially in the low signal to noise ratio(SNR)scenarios.To address this issue,an improved frame iterative spectral subtraction in the STM domain(IMModSSub)is proposed.More specifically,with the inter-frame correlation,the noise subtraction is directly applied to handle the noisy signal for each frame in the STM domain.Then,the noisy signal is classified into speech or silence frames based on a predefined threshold of segmented SNR.With these classification results,a corresponding mask function is developed for noisy speech after noise subtraction.Finally,exploiting the increased sparsity of speech signal in the modulation domain,the orthogonal matching pursuit(OMP)technique is employed to the speech frames for improving the speech quality and intelligibility.The effectiveness of the proposed method is evaluated with three types of noise,including white noise,pink noise,and hfchannel noise.The obtained results show that the proposed method outperforms some established baselines at lower SNRs(-5 to +5 dB). 展开更多
关键词 short-time modulation domain single-channel speech enhancement modulation improved frame iterative spectral subtraction low snrs
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Feature Extraction of Localized Scattering Centers Using the Modified TLS-Prony Algorithm and Its Applications 被引量:5
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作者 Wang Jun Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, P.R.China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2002年第3期31-39,共9页
This paper presents an all-parametric model of radar target in optic region, in which the localized scattering center's frequency and aspect angle dependent scattering level, distance and azimuth locations are mod... This paper presents an all-parametric model of radar target in optic region, in which the localized scattering center's frequency and aspect angle dependent scattering level, distance and azimuth locations are modeled as the feature vectors. And the traditional TLS-Prony algorithm is modified to extract these feature vectors. The analysis of Cramer-Rao bound shows that the modified algorithm not only improves the restriction of high signal-to-noise ratio(SNR)threshold of traditional TLS-Prony algorithm, but also is suitable to the extraction of big damped coefficients and high-resolution estimation of near separation poles. Finally, an illustrative example is presented to verify its practicability in the applications. The experimental results show that the method developed can not only recognize two airplane-like targets with similar shape at low SNR, but also compress the original radar data with high fidelity. 展开更多
关键词 Localized scattering centers Estimation algorithm low SNR High resolution.
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Golay Pair Aided Timing Synchronization Algorithm for Distributed MIMO-OFDM System 被引量:1
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作者 Weizhi Zhong Xiaoyi Lu +1 位作者 Lei Xu Xin Liu 《China Communications》 SCIE CSCD 2018年第9期178-188,共11页
In order to solve the problem of inaccurate synchronization for distributed multiple-input multiple-output(MIMO) orthogonal frequency division multiplexing(OFDM) system in both multipath and low signal to noise ratio(... In order to solve the problem of inaccurate synchronization for distributed multiple-input multiple-output(MIMO) orthogonal frequency division multiplexing(OFDM) system in both multipath and low signal to noise ratio(SNR) channels, a golay pair aided timing synchronization(GPATS) method is proposed in this paper. A new synchronous training sequence based on the golay pair with guard interval is designed in GPATS method. By utilizing the unique properties of the new training sequence, the different timing point and the inter-transmitter delays(ITD) are obtained at the receiver. Simulation results show that, compared with the traditional synchronization approaches, the proposed algorithm can provide high accuracy in detecting different time offsets caused by the distributed transmitters of the MIMO-OFDM system, especially over multipath and low SNR channels. 展开更多
关键词 distributed MIMO-OFDM system timing synchronization golay pair MULTIPATH low SNR
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Long term integration of radar signals with unknown Doppler shift for ubiquitous radar 被引量:4
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作者 Qinglong Bao Zengping Chen Yue Zhang Jian Yang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第2期219-227,共9页
Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in "pop-up" targets in clutter to long-range target... Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in "pop-up" targets in clutter to long-range targets impacts selection of waveform parameters. The coherent processing interval (CPI) must be long enough to achieve a certain signal-to-noise ratio (SNR) that ensures the efficiency of detection. The condition of detection in the case of low SNR is analyzed, and three different cases that would occur during integration are discussed and a method to determine the CPI is presented. The simulation results show that targets detection with SNR as low as -26 dB in the experimental system can possibly determine the CPI. 展开更多
关键词 ubiquitous radar low signal-to-noise ratio (SNR) coherent processing interval (CPI) coherent integration non-coherent integration.
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DOA estimation based on multi-frequency joint sparse Bayesian learning for passive radar 被引量:1
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作者 WEN Jinfang YI Jianxin +2 位作者 WAN Xianrong GONG Ziping SHEN Ji 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2022年第5期1052-1063,共12页
This paper considers multi-frequency passive radar and develops a multi-frequency joint direction of arrival(DOA)estimation algorithm to improve estimation accuracy and resolution.The developed algorithm exploits the ... This paper considers multi-frequency passive radar and develops a multi-frequency joint direction of arrival(DOA)estimation algorithm to improve estimation accuracy and resolution.The developed algorithm exploits the sparsity of targets in the spatial domain.Specifically,we first extract the required frequency channel data and acquire the snapshot data through a series of preprocessing such as clutter suppression,coherent integration,beamforming,and constant false alarm rate(CFAR)detection.Then,based on the framework of sparse Bayesian learning,the target’s DOA is estimated by jointly extracting the multi-frequency data via evidence maximization.Simulation results show that the developed algorithm has better estimation accuracy and resolution than other existing multi-frequency DOA estimation algorithms,especially under the scenarios of low signalto-noise ratio(SNR)and small snapshots.Furthermore,the effectiveness is verified by the field experimental data of a multi-frequency FM-based passive radar. 展开更多
关键词 multi-frequency passive radar DOA estimation sparse Bayesian learning small snapshot low signal-to-noise ratio(SNR)
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Novel high-resolution DOA estimation using subspace projection method 被引量:7
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作者 SI Wei-jian LAN Xiao-yu ZOU Yan 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2012年第4期110-116,共7页
The performance of multiple signal classification (MUSIC) algorithm with regard to solving closely spaced direction of arrivals (DOAs) depends strongly upon the signal-to-noise ratio (SNR) and snapshots. In orde... The performance of multiple signal classification (MUSIC) algorithm with regard to solving closely spaced direction of arrivals (DOAs) depends strongly upon the signal-to-noise ratio (SNR) and snapshots. In order to solve this problem, a method by reconstructing the spatial spectrum function with both noise subspace and signal subspace is presented in this paper. The key idea is to apply the full information contained in covariance matrix and change the projection weights of steering vector on the noise and signal subspace by their revised eigenvalues, respectively. Comparing with the MUSIC algorithm, it does not increase any computational complexity either, and remarkably, it has the advantages of simultaneously reducing noise and keeping the high-resolution ability under low SNR and small sample sized scenarios. Simulation and experiment results are included to demonstrate the superior performance of the proposed algorithm. 展开更多
关键词 direction &arrival (DOA) multiple signal classification low SNR RESOLUTION subspace projection
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