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Neural network approach to blindestimation of PN spreading sequence in lower SNR DS/SS signals 被引量:6
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作者 Zhang Tianqi Lin Xiaokang Zhou Zhengzhong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第4期756-760,共5页
An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extr... An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extraction of unsupervised neural networks are exploited adequately. Theoretical analysis and experimental results are provided to show that this approach can work well on the lower S/N ratio input signals. 展开更多
关键词 discrete Karhunen-Loeve transformation neural networks direct sequence spread spectrum (DS/SS) signal PN sequence.
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Approach to blind estimation of the PN sequence in DS-SS signals with residual carrier 被引量:8
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作者 Tianqi Zhang Shaosheng Dai +2 位作者 Guoning Ma Wei Zhang Pu Miao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第1期1-8,共8页
This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) dire... This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) direct sequence spread spectrum (DS-SS) signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR. 展开更多
关键词 direct sequence spread spectrum (DS-SS) signal pseudo-noise (PN) sequence blind estimation singular value de-composition digital phase lock loop residual carrier.
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High-Sensitivity Acquisition of Ultrahigh Dynamic Direct Sequence Spread Spectrum Signals in Space Communications 被引量:2
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作者 徐颖 袁洪 《China Communications》 SCIE CSCD 2013年第10期26-36,共11页
According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the ... According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the phase of Pseudo-Noise-code(PN-code),Doppler frequency and its rate-of-change is presented to achieve high sensitivity in sensing high-frequency dynamics. By eliminating the correlation peak loss caused by ultrahigh Doppler frequency and its rate-of-change offset,the proposed method improves the acquisition sensitivity by increasing the non-coherent accumulation time. The validity of the algorithm is proved by theoretical analysis and simulation results. It is shown that signals with a carrier- to-noise ratio as low as 39 dBHz can be captured with high performance when the Doppler frequency is up to ±1 MHz and its rate-of-change is up to ±200 kHz/s. 展开更多
关键词 direct sequence spread spectrum signals space communications ACQUISITION high sensitivity ultrahigh dynamic
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Fast method for spreading sequence estimation of DSSS signal based on maximum likelihood function 被引量:12
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作者 Yanhua Peng Bin Tang Ming Lv 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第6期948-953,共6页
To estimate the spreading sequence of the direct sequence spread spectrum (DSSS) signal, a fast algorithm based on maximum likelihood function is proposed, and the theoretical derivation of the algorithm is provided. ... To estimate the spreading sequence of the direct sequence spread spectrum (DSSS) signal, a fast algorithm based on maximum likelihood function is proposed, and the theoretical derivation of the algorithm is provided. By simplifying the objective function of maximum likelihood estimation, the algorithm can realize sequence synchronization and sequence estimation via adaptive iteration and sliding window. Since it avoids the correlation matrix computation, the algorithm significantly reduces the storage requirement and the computation complexity. Simulations show that it is a fast convergent algorithm, and can perform well in low signal to noise ratio (SNR). 展开更多
关键词 direct sequence spread spectrum (DSSS) signal spreading sequence maximum likelihood estimation (MLE).
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A Neural Network Approach to Blind Estimation of PN Spreading Sequence in DS/SS Signals 被引量:1
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作者 张天麒 周正中 《Journal of Electronic Science and Technology of China》 2004年第2期1-6,共6页
In this paper, a new approach is proposed to estimate pseudo noise(PN) sequence in the lower SNR DS/SS signals blindly. This method utilizes the characteristics of self-organization, principal components analysis and ... In this paper, a new approach is proposed to estimate pseudo noise(PN) sequence in the lower SNR DS/SS signals blindly. This method utilizes the characteristics of self-organization, principal components analysis and extraction of unsupervised neural networks adequately, in addition to its higher-speed operation ability, successfully solve the difficult problem about PN sequence blind estimation. The theoretic analysis and experimental results show that this approach can work very well on lower SNR input signals. 展开更多
关键词 neural networks direct sequence spread spectrum signal PN sequence
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Non-Supervised Learning for Spread Spectrum Signal Pseudo-Noise Sequence Acquisition
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作者 Hao Cheng Na Yu Tai-Jun Wang 《Journal of Electronic Science and Technology》 CAS CSCD 2015年第1期83-86,共4页
An idea of estimating the direct sequence spread spectrum(DSSS) signal pseudo-noise(PN) sequence is presented. Without the apriority knowledge about the DSSS signal in the non-cooperation condition, we propose a s... An idea of estimating the direct sequence spread spectrum(DSSS) signal pseudo-noise(PN) sequence is presented. Without the apriority knowledge about the DSSS signal in the non-cooperation condition, we propose a self-organizing feature map(SOFM) neural network algorithm to detect and identify the PN sequence. A non-supervised learning algorithm is proposed according the Kohonen rule in SOFM. The blind algorithm can also estimate the PN sequence in a low signal-to-noise(SNR) and computer simulation demonstrates that the algorithm is effective. Compared with the traditional correlation algorithm based on slip-correlation, the proposed algorithm's bit error rate(BER) and complexity are lower. 展开更多
关键词 Blind estimation direct sequence spread spectrum signal non-supervised learning pseudo-noise sequence
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Knowledge-based potentials in bioinformatics: From a physicist's viewpoint 被引量:1
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作者 郑伟谋 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第12期22-27,共6页
Biological raw data are growing exponentially, providing a large amount of information on what life is. It is believed that potential functions and the rules governing protein behaviors can be revealed from analysis o... Biological raw data are growing exponentially, providing a large amount of information on what life is. It is believed that potential functions and the rules governing protein behaviors can be revealed from analysis on known native structures of proteins. Many knowledge-based potentials for proteins have been proposed. Contrary to most existing review articles which mainly describe technical details and applications of various potential models, the main foci for the discussion here are ideas and concepts involving the construction of potentials, including the relation between free energy and energy, the additivity of potentials of mean force and some key issues in potential construction. Sequence analysis is briefly viewed from an energetic viewpoint. 展开更多
关键词 Knowledge-based potentials for proteins protein native structures sequence signals
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Propagation of quasi-periodic random sound pulse sequence signals in shallow-water waveguides 被引量:1
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作者 SUN Junping LIN Jianheng +4 位作者 YANG Jun JIANG Guojian YI Xuejuan JIANG Pengfei ZHAO Zhendong 《Chinese Journal of Acoustics》 CSCD 2017年第3期328-336,共9页
It is an efficient method to model ship radiated noise as quasi-periodic random sound pulse sequences. Based on the model, this paper discusses the characteristics change of ship noise after through shallow-water wave... It is an efficient method to model ship radiated noise as quasi-periodic random sound pulse sequences. Based on the model, this paper discusses the characteristics change of ship noise after through shallow-water waveguides. Theoretical analysis and numerical simulation show that random waveguides and multi-path effects can bring much additional transmission loss for the noise line spectra, demonstrating the instability of ship radiated noise line spectra to a certain extent, and providing some theoretical support for advanced studies of ship radiated noise. 展开更多
关键词 Propagation of quasi-periodic random sound pulse sequence signals in shallow-water waveguides line
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Subspace decomposition-based correlation matrix multiplication
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作者 Cheng Hao Guo Wei Yu Jingdong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第2期241-245,共5页
The correlation matrix, which is widely used in eigenvalue decomposition (EVD) or singular value decomposition (SVD), usually can be denoted by R = E[yiy'i]. A novel method for constructing the correlation matrix... The correlation matrix, which is widely used in eigenvalue decomposition (EVD) or singular value decomposition (SVD), usually can be denoted by R = E[yiy'i]. A novel method for constructing the correlation matrix R is proposed. The proposed algorithm can improve the resolving power of the signal eigenvalues and overcomes the shortcomings of the traditional subspace methods, which cannot be applied to low SNR. Then the proposed method is applied to the direct sequence spread spectrum (DSSS) signal's signature sequence estimation. The performance of the proposed algorithm is analyzed, and some illustrative simulation results are presented. 展开更多
关键词 subspace theory correlation matrix eigenvalue decomposition direct sequence spread spectrum signal
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Design and implementation of the NaI(Tl)/CsI(Na) detectors output signal generator
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作者 周旭 刘聪展 +8 位作者 赵建领 张飞 张翼飞 李正伟 张硕 李旭芳 路雪峰 许振玲 卢方军 《Chinese Physics C》 SCIE CAS CSCD 2014年第2期45-49,共5页
We designed and implemented a signal generator that can simulate the output of the NaI(Tl)/CsI(Na)detectors'pre-amplifier onboard the Hard X-ray Modulation Telescope(HXMT).Using the development of the FPGA(Fie... We designed and implemented a signal generator that can simulate the output of the NaI(Tl)/CsI(Na)detectors'pre-amplifier onboard the Hard X-ray Modulation Telescope(HXMT).Using the development of the FPGA(Field Programmable Gate Array)with VHDL language and adding a random constituent,we have finally produced the double exponential random pulse signal generator.The statistical distribution of the signal amplitude is programmable.The occurrence time intervals of the adjacent signals contain negative exponential distribution statistically. 展开更多
关键词 FPGA M sequence rejection technique Gaussian distribution signal generator
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