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SUBSAMPLE TIME DELAY ESTIMATION BASED ON PHASE SPECTRUM OF BAND LIMITED STOCHASTIC SIGNALS 被引量:4
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作者 柏业超 张兴敢 唐岚 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2010年第2期170-175,共6页
The accuracy of conventional time delay estimation (TDE) algorithms is limited by the sampling interval. A novel algorithm of subsample TDE suitable for widehand signals is presented to improve the accuracy. This al... The accuracy of conventional time delay estimation (TDE) algorithms is limited by the sampling interval. A novel algorithm of subsample TDE suitable for widehand signals is presented to improve the accuracy. This algorithm applies periodogram and parabolic interpolation to the cross correlation spectrum of band limited stochastic signals, and can obtain a continuous time delay estimator. Simulations are carried out to compare the performance of the proposed algorithm with that of other subsample TDE algorithms. Results show that the proposed algorithm outperforms other algorithms and reachs the Cramer-Rao lower bound (CRLB) at a high signal- to-noise ratio. For the wideband characteristic and the randomness of the transmitting signal, the proposed algo- rithm is suitable for the low probability of intercept radars. 展开更多
关键词 parameter estimation time delay cross-power density spectra INTERPOLATION PERIODOGRAM
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Observations and modelling of the travel time delay and leading negative phase of the 16 September 2015 Illapel,Chile tsunami
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作者 Peitao Wang Zhiyuan Ren +4 位作者 Lining Sun Jingming Hou Zongchen Wang Ye Yuan Fujiang Yu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第11期11-30,共20页
The systematic discrepancies in both tsunami arrival time and leading negative phase(LNP)were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel,Chile by examining the wave characteristics ... The systematic discrepancies in both tsunami arrival time and leading negative phase(LNP)were identified for the recent transoceanic tsunami on 16 September 2015 in Illapel,Chile by examining the wave characteristics from the tsunami records at 21 Deep-ocean Assessment and Reporting of Tsunami(DART)sites and 29 coastal tide gauge stations.The results revealed systematic travel time delay of as much as 22 min(approximately 1.7%of the total travel time)relative to the simulated long waves from the 2015 Chilean tsunami.The delay discrepancy was found to increase with travel time.It was difficult to identify the LNP from the near-shore observation system due to the strong background noise,but the initial negative phase feature became more obvious as the tsunami propagated away from the source area in the deep ocean.We determined that the LNP for the Chilean tsunami had an average duration of 33 min,which was close to the dominant period of the tsunami source.Most of the amplitude ratios to the first elevation phase were approximately 40%,with the largest equivalent to the first positive phase amplitude.We performed numerical analyses by applying the corrected long wave model,which accounted for the effects of seawater density stratification due to compressibility,self-attraction and loading(SAL)of the earth,and wave dispersion compared with observed tsunami waveforms.We attempted to accurately calculate the arrival time and LNP,and to understand how much of a role the physical mechanism played in the discrepancies for the moderate transoceanic tsunami event.The mainly focus of the study is to quantitatively evaluate the contribution of each secondary physical effect to the systematic discrepancies using the corrected shallow water model.Taking all of these effects into consideration,our results demonstrated good agreement between the observed and simulated waveforms.We can conclude that the corrected shallow water model can reduce the tsunami propagation speed and reproduce the LNP,which is observed for tsunamis that have propagated over long distances frequently.The travel time delay between the observed and corrected simulated waveforms is reduced to<8 min and the amplitude discrepancy between them was also markedly diminished.The incorporated effects amounted to approximately 78%of the travel time delay correction,with seawater density stratification,SAL,and Boussinesq dispersion contributing approximately 39%,21%,and 18%,respectively.The simulated results showed that the elastic loading and Boussinesq dispersion not only affected travel time but also changed the simulated waveforms for this event.In contrast,the seawater stratification only reduced the tsunami speed,whereas the earth’s elasticity loading was responsible for LNP due to the depression of the seafloor surrounding additional tsunami loading at far-field stations.This study revealed that the traditional shallow water model has inherent defects in estimating tsunami arrival,and the leading negative phase of a tsunami is a typical recognizable feature of a moderately strong transoceanic tsunami.These results also support previous theory and can help to explain the observed discrepancies. 展开更多
关键词 2015 Chilean tsunami travel time delay leading negative phase numerical modeling corrected long wave earth’s elasticity loading seawater density stratification Boussinesq dispersion
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简化的基于时延线性拟合的宽带测向算法 被引量:2
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作者 刘兴华 罗景青 刘伟山 《现代防御技术》 北大核心 2016年第1期186-191,共6页
干涉仪体制下,利用拟合时延的方法估计宽带信号的波达角,需要对模糊的互谱相位进行拼接,处理过程复杂。为此,提出了一种测向算法,在给定接收机带宽下,只要基线长度小于一定数值,就可以无需相位拼接和解模糊处理直接拟合时延。从理论上... 干涉仪体制下,利用拟合时延的方法估计宽带信号的波达角,需要对模糊的互谱相位进行拼接,处理过程复杂。为此,提出了一种测向算法,在给定接收机带宽下,只要基线长度小于一定数值,就可以无需相位拼接和解模糊处理直接拟合时延。从理论上分析了算法的测角性能,并给出影响测角精度的因素。仿真实验验证了理论的正确性和算法的有效性。 展开更多
关键词 宽带信号 互谱 测向 时延线性拟合 相位拼接 最小二乘估计
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自适应相位谱时间延迟估计 被引量:3
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作者 邱天爽 王宏禹 《大连铁道学院学报》 1997年第2期19-25,共7页
提出了一种自适应相位谱时间延迟估计方法该法利用时域或频域LMS自适应滤波器,自适应地实现Roth处理器即维纳滤波器。
关键词 时间延迟 估计 自适应相位谱 滤波器 信号处理
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Multipath tracking with LTE signals for accurate TOA estimation in the application of indoor positioning 被引量:1
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作者 Zhaoliang Liu Liang Chen +2 位作者 Xin Zhou Nan Shen Ruizhi Chen 《Geo-Spatial Information Science》 SCIE EI CSCD 2023年第1期31-43,共13页
Indoor positioning with high accuracy plays an important role in different application scenar-ios.As a widely used mobile communication signal,the Long-Term Evolution(LTE)network can be well received in indoor and out... Indoor positioning with high accuracy plays an important role in different application scenar-ios.As a widely used mobile communication signal,the Long-Term Evolution(LTE)network can be well received in indoor and outdoor environments.This article studies a method of using different reference signals in the LTE downlink for carrier phase time of arrival(TOA)estimation.Specifically,a solution is proposed and a multipath tracking Software Defined Receiver(SDR)is developed for indoor positioning.With our SDR indoor positioning system,the pilot signals of the LTE signals are firstly obtained by the coarse synchronization and demodulation.Then,with the assistance of the pilot signals,the time delay acquisition,the multipath estimating delay lock loop(MEDLL)algorithm,and the multipath anomaly detection are sequentially carried out to obtain navigation observations of received signals.Furthermore,to compare the perfor-mance of different pilot signals,the Secondary Synchronous Signals(SSS)and Cell Reference Signals(CRS)are used as pilot signals for carrier phase-based TOA estimation,respectively.Finally,to quantify the accuracy of our multipath tracking SDR,indoor field tests are carried out in a conference environment,where an LTE base station is installed for commercial use.Our test results based on CRS show that,in the static test scenarios,the TOA accuracy measured by the 1-σerror interval is about 0.5 m,while in the mobile environment,the probability of range accuracy within 1.0 m is 95%. 展开更多
关键词 Long-Term Evolution(LTE) indoor positioning multipath estimation delay locked loop(MEDLL) carrier phase time of arrival(TOA)
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基于贝叶斯序列分割的高维时间序列在线分类算法
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作者 尹君 张建业 +2 位作者 李德高 景康 周平 《计算机应用与软件》 北大核心 2021年第8期322-328,共7页
参数化密度估计算法和非参数化密度估计算法均无法高效地处理高维时间序列。针对这种情况,提出基于贝叶斯序列分割的高维时间序列在线分类算法。通过时间延迟嵌入将时间序列投影到重建相位空间,基于贝叶斯序列分割将时间序列分区,结合... 参数化密度估计算法和非参数化密度估计算法均无法高效地处理高维时间序列。针对这种情况,提出基于贝叶斯序列分割的高维时间序列在线分类算法。通过时间延迟嵌入将时间序列投影到重建相位空间,基于贝叶斯序列分割将时间序列分区,结合边际密度和copula变换计算每个区的密度。使用积分平方误差度量时间序列概率密度函数之间的相似性。实验结果表明,该方法对于时间序列的维度具有鲁棒性,能高效地估计时间序列的密度,获得满意的时间序列分类准确率,同时满足在线分类的要求。 展开更多
关键词 高维时间序列 在线分类 边际密度估计 积分平方误差 贝叶斯序列分割 重建相位空间
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