Compared to the rank reduction estimator （RARE） based on second-order statistics （called SOS-RARE）, the RARE employing fourth-order cumulants （referred to as FOC-RARE） is capable of dealing with more sources and...Compared to the rank reduction estimator （RARE） based on second-order statistics （called SOS-RARE）, the RARE employing fourth-order cumulants （referred to as FOC-RARE） is capable of dealing with more sources and mitigating the negative influences of the Gaussian colored noise. However, in the presence of unexpected modeling errors, the resolution behavior of the FOC-RARE also deteriorate significantly as SOS-RARE, even for a known array covariance matrix. For this reason, the angle resolution capability of the FOC-RARE was theoretically analyzed. Firstly, the explicit formula for the mathematical expectation of the FOC-RARE spatial spectrum was derived through the second-order perturbation analysis method. Then, with the assumption that the unexpected modeling errors were drawn from complex circular Gaussian distribution, the theoretical formulas for the angle resolution probability of the FOC-RARE were presented. Numerical experiments validate our analytical results and demonstrate that the FOC-RARE has higher robustness to the unexpected modeling en＇ors than that of the SOS-RARE from the resolution point of view.展开更多
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
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
An algorithm to detect and recognize interferences embedded in a direct sequence spread spectrum (DSSS) communication system is proposed. Based on Welch's averaging modified periodogram method and fractional Fouri...An algorithm to detect and recognize interferences embedded in a direct sequence spread spectrum (DSSS) communication system is proposed. Based on Welch's averaging modified periodogram method and fractional Fourier transformation (FRFT), the paper proposes a decision tree-based algorithm in which a set of decision criteria for identifying different types of interferences is developed. Simulation results demonstrate that the proposed algorithm provides a high recognition rate and is robust for various ISR and SNR.展开更多
无人机协同目标感知技术是有人机无人机混合运行的重要安全保障.针对复杂空域环境下的感知可靠性问题,分析大中型无人机的复杂融合空域运行场景,并确定无人机协同目标感知的精准性、高实时性、抗干扰性和低载荷性等需求,提出一种四单元...无人机协同目标感知技术是有人机无人机混合运行的重要安全保障.针对复杂空域环境下的感知可靠性问题,分析大中型无人机的复杂融合空域运行场景,并确定无人机协同目标感知的精准性、高实时性、抗干扰性和低载荷性等需求,提出一种四单元阵列天线和数字化射频体制的无人机协同目标感知系统架构;同时,结合空管雷达信号特性和天线体制,设计方位感知算法,通过修正协方差矩阵、信号子空间加权和噪声子空间加权等方法,设计基于多信号分类(multiple signal classification,MUSIC)的空间谱估计算法,并提出基于子空间分解的幅相误差在线估计算法;最后,开展算法仿真试验和实际空域环境飞行试验.研究结果表明:相比传统MUSIC算法,优化算法的方位感知高分辨性能提升23.3%,并改善了无人机协同目标方位感知的高实时性、抗干扰性和低载荷性.展开更多
基金Project(61201381)supported by the National Nature Science Foundation of ChinaProject(YP12JJ202057)supported by the Future Development Foundation of Zhengzhou Information Science and Technology College,China
文摘Compared to the rank reduction estimator （RARE） based on second-order statistics （called SOS-RARE）, the RARE employing fourth-order cumulants （referred to as FOC-RARE） is capable of dealing with more sources and mitigating the negative influences of the Gaussian colored noise. However, in the presence of unexpected modeling errors, the resolution behavior of the FOC-RARE also deteriorate significantly as SOS-RARE, even for a known array covariance matrix. For this reason, the angle resolution capability of the FOC-RARE was theoretically analyzed. Firstly, the explicit formula for the mathematical expectation of the FOC-RARE spatial spectrum was derived through the second-order perturbation analysis method. Then, with the assumption that the unexpected modeling errors were drawn from complex circular Gaussian distribution, the theoretical formulas for the angle resolution probability of the FOC-RARE were presented. Numerical experiments validate our analytical results and demonstrate that the FOC-RARE has higher robustness to the unexpected modeling en＇ors than that of the SOS-RARE from the resolution point of view.
基金supported by the National Natural Science Foundation of China (10776040 60602057)+4 种基金Program for New Century Excellent Talents in University (NCET)the Project of Key Laboratory of Signal and Information Processing of Chongqing (CSTC2009CA2003)the Natural Science Foundation of Chongqing Science and Technology Commission (CSTC2009BB2287)the Natural Science Foundation of Chongqing Municipal Education Commission (KJ060509 KJ080517)
文摘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.
基金supported by Joint Foundation of and China Academy of Engineering Physical (10676006)
文摘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).
基金Sponsored by the Ministerial Foundation of China (41001020201 and 11002040105)
文摘An algorithm to detect and recognize interferences embedded in a direct sequence spread spectrum (DSSS) communication system is proposed. Based on Welch's averaging modified periodogram method and fractional Fourier transformation (FRFT), the paper proposes a decision tree-based algorithm in which a set of decision criteria for identifying different types of interferences is developed. Simulation results demonstrate that the proposed algorithm provides a high recognition rate and is robust for various ISR and SNR.
文摘无人机协同目标感知技术是有人机无人机混合运行的重要安全保障.针对复杂空域环境下的感知可靠性问题,分析大中型无人机的复杂融合空域运行场景,并确定无人机协同目标感知的精准性、高实时性、抗干扰性和低载荷性等需求,提出一种四单元阵列天线和数字化射频体制的无人机协同目标感知系统架构;同时,结合空管雷达信号特性和天线体制,设计方位感知算法,通过修正协方差矩阵、信号子空间加权和噪声子空间加权等方法,设计基于多信号分类(multiple signal classification,MUSIC)的空间谱估计算法,并提出基于子空间分解的幅相误差在线估计算法;最后,开展算法仿真试验和实际空域环境飞行试验.研究结果表明:相比传统MUSIC算法,优化算法的方位感知高分辨性能提升23.3%,并改善了无人机协同目标方位感知的高实时性、抗干扰性和低载荷性.
