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We propose an optimal interpolation filter for symbol timing recovery in a digital receiver where the input analog-to-digital (A-D) conversion sampling clock is not synchronized to the transmitter symbol clock. The optimal filter is designed by minimizing the mean-square error (MSE) at the output of the receiver, assuming that the correct timing difference between the nonsynchronized input samples and the correct strobe synchronized to the symbol is given. The MSE minimization procedure results in a system of linear equations which can easily be solved to yield the optimal filter coefficients. We also analyze the symbol tracking performance of a symbol synchronizer that employs the proposed optimal interpolation filter. Although the proposed optimal filter is designed assuming the availability of the correct timing difference, we show that it minimizes the timing estimation error variance even when the computed timing difference values deviate from the ideal, we also show that the timing estimation is virtually unbiased if the length of the interpolation filter is greater than or equal to 4. Simulation results are included to show the performance improvement realizable by employing the optimal interpolation filter 相似文献
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Five standard configurations for optical demultiplexing of optical time domain multiplexed signals are compared. In terms of component usage and strobe signal requirements they are surprisingly equivalent. Both fiber loop and Mach-Zehnder configurations are studied. Fiber rings yield good stability, while configurations based on fiber Mach-Zehnder interferometers, in return, offer the possibility of add/drop demultiplexing. A new Mach-Zehnder configuration is proposed, which requires less optical components, only one strobe signal and has no optical losses (except from excess losses in couplers and splices). The sensitivity to power levels, fiber attenuation, signal and strobe wavelengths, etc., are analyzed and a preliminary design for a 100 to 5×20 Gb/s demultiplexer is suggested 相似文献
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Strobe double phase estimator: a multipath mitigating technique for BOC signal in GNSS based on double phase estimator 下载免费PDF全文
Xu Chengtao Liu Zhe Tang Xiaomei Wang Feixue 《International Journal of Satellite Communications and Networking》2017,35(3):249-261
Double phase estimator (DPE) is an unambiguous binary offset carrier (BOC) tracking algorithm for band‐limited receivers in Global Navigation Satellite Systems. Based on the strobe pulse method, the DPE was modified by introducing a strobe waveform in the prompt signal correlation process of the subcarrier phase lock loop in this paper.. This strobe DPE (SDPE) employs no additional correlators. Two different reference strobe waveforms and their receiving structures are provided. The performance of the SDPE is characterized according to the subcarrier multipath error envelope (SMEE) and the tracking jitter. Simulation results show that, relative to conventional DPE, the first waveform employed in this study provides a reduction in the SMEE area of 81.1% and 75.1% for BOC(1,1) and BOC(14,2) signal, respectively. The second waveform employed in this study provides a reduction in the SMEE area of 82.5% and 76.8% for BOC(1,1) and BOC(14,2) signal, respectively. They also both outperform the double estimator about 64.4% and 53.2% for BOC(1,1) and BOC(14,2) signal in the SMEE area. However, the SDPE experiences a loss of ?6 and ?7.25 dB, respectively, for two reference waveforms in terms of the post‐coherent signal‐to‐noise ratio, which impacts its tracking precision. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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第3代北斗卫星导航系统中B1C频点信号将使用正交复用二进制偏移载波调制方式。为了增强北斗卫星导航接收机码跟踪环路的抗多径性能并且解决码跟踪中的模糊跟踪问题,该文针对正交复用二进制偏移载波调制信号QMBOC(6, 1, 4/33)提出一种双闸波码跟踪环路结构。根据理想的目标鉴相函数和二进制偏移载波调制信号自相关函数的特点分别设计出针对BOC(1, 1)和BOC(6, 1)信号的闸波,并在本地码跟踪环路中使用这两种不同的闸波分别与输入信号相关,最后将所得的两个相关函数进行加权合并以用于鉴相过程。计算机仿真结果表明所提方法不仅能够有效消除QMBOC(6, 1, 4/33)信号的模糊跟踪可能性,且能够大幅增强接收机的抗多径性能,其对应多径误差包络面积相比于现有的方法能够减少约33%。 相似文献
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在对BPSK调制信号特性分析的基础上,介绍了对符号速率估计的一种方法,即通过提取信号包络中的重复频率来获得符号速率。在实际应用中发现,这种方法在数据符号个数较少时,受到非线性变换带来的低端噪声的影响较大,直接对信号包络的幅度谱求最大值难以正确估计出符号速率。在对问题进行分析的基础上引入了一种改进的方法,对导致估计错误的背景噪声进行抑制,从而突显出符号速率谱线。最后着重阐述了改进算法的FPGA实现方案。 相似文献
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《Communications Letters, IEEE》2002,6(5):205-207
A new non-data-aided feedforward symbol timing estimator is proposed, which can apply to two samples per symbol. Numerical results show the proposed estimator is approximately unbiased. Computational complexity of the new estimator is even simpler than conventional estimators with two samples per symbol. Estimation accuracy of the new estimator is similar to that of the conventional estimator with four samples per symbol presented by Oerder and Meyr in 1988, which is the simplest among the estimators using four samples per symbol. While some conventional estimators have better estimation accuracy than the proposed, this estimator has an attractive advantage over the formers from an implementation point of view 相似文献
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将点军标显示避让问题当作空间竞争问题求解,提出一种基于社会活动领域的满意度移动模型的点军标自动避让方法。该方法以点军标显示最小外接矩形重叠区域大小作为军标满意度,将点军标配置位置的四方向领域作为移动备选位置,通过多次迭代使得各点军标位于其满意度最大位置,将此满意度最大的点军标集合作为避让标绘的结果。实验结果表明,该方法能够较好解决点军标显示占位冲突,实现自动避让标绘。 相似文献
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A novel NAND flash memory interface (NFMI) scheme to cope with uncertainty due to process, voltage and temperature (PVT) variations is proposed. The new NFMI scheme introduces a signal called data valid strobe to replace the signal read enable bar, which is a read strobe in the standard NFMI protocol. Experimental results show that the proposed scheme is insensitive to PVT variations, unlike the existing NFMI scheme, and hence substantially increases system performance as well as reliability 相似文献
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Nature photography was almost the first application of the electronic flash system of lighting when it became commonly available.1 Although these first units used paper capacitors charged to high voltages and discharging at microsecond rates, later ``strobes' employed lower-voltage capacitors and operated at longer flash durations. Hence, today's conventional strobe is not suitable for the rapidly moving subjects of nature photography. This article describes a development in strobe equipment that incorporates new and improved design to create flash units of not only lighter weight, but with exposure times of less than 100 microseconds. 相似文献
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Nose-to-nose校准技术的理论基础是:kick-out脉冲正比于取样示波器系统的冲激响应.Jan verspecht博士和美国国家标准技术研究院(NIST)用S参数法对此进行了详尽的分析.本文从电路理论分析入手,对kick-out脉冲产生的机理重新进行了分析,得出了十分有用的数学表达式和结论:kick-out 脉冲不仅与电路参数有关,而且与选通脉冲有关.这一结论并被计算机的仿真所证实,这用以前的理论是无法解释的.可以说本文结论进一步完善了NTN校准技术的理论依据. 相似文献
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The maximum likelihood decision statistic for pulse-position modulated (PPM) signals governed by an arbitrary discrete point process in the presence of additive Gaussian noise is derived. Sufficient conditions are given for determining when the optimum PPM symbol detection strategy is to choose the PPM symbol corresponding to the maximum slot statistic. In particular, it is shown that for the important case of Webb distributed avalanche photodiode output electrons in the presence of Gaussian noise, the optimum decision rule is to choose the largest slot observable 相似文献
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As the raised cosine shaping filter is often employed in practical satellite communication system,the envelope fluctuation at the symbol transition point is decreased which leads to the failure of the common wavelet algorithm under low SNR.Accordingly,a method of blind symbol rate estimation using signal preprocessing and Haar wavelet is proposed in this paper.Firstly,the effect of filter shaping can be reduced by the signal preprocessing.Then,the optimal scale factor is searched and the signal is processed and analyzed by the Haar wavelet transform.Finally,the symbol rate line is extracted and a nonlinear filter method is inducted for improving the estimation performance.Theoretical analysis and computer simulation show the efficiency of the proposed algorithm under low SNR and small roll-off factor. 相似文献
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An optically strobed sampling oscilloscope is described in which a GaAs laser diode is used to strobe a GaAs photoconductive sampling gate. 相似文献
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提出了一种数字通信信号码元速率的估计算法。对截获接收机输出的调制信号提取基带信号,利用此基带信号小波变换系数的模值,构造与原调制信号码速率一致的单极性脉冲序列。通过对此单极性脉冲序列的功率谱分析可知,在基带信号码元速率的整数倍处存在离散谱线,检测这些离散谱线即实现了信号码元速率的估计。这种算法能在低信噪比下估计信号的码元速率。理论分析和实际信号处理证明了本文提出算法的可行性。 相似文献