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短波低信噪比OFDM猝发通信系统同步算法 被引量:3
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作者 范慧丽 孙景芳 杨平 《四川大学学报(工程科学版)》 EI CAS CSCD 北大核心 2011年第6期158-162,共5页
为解决低信噪比下短波正交频分复用(OFDM)系统信号的捕获,提出了一种采用CAZAC序列设计导频符号的基于谱分析的同步算法。首先通过时域、频域2维联合估计来实现信号的快速捕获,同时根据信号谱函数的最大峰值位置来确定整数频偏,然后利... 为解决低信噪比下短波正交频分复用(OFDM)系统信号的捕获,提出了一种采用CAZAC序列设计导频符号的基于谱分析的同步算法。首先通过时域、频域2维联合估计来实现信号的快速捕获,同时根据信号谱函数的最大峰值位置来确定整数频偏,然后利用相邻导频符号的相位差来精确估计小数频偏。最后,进行了算法仿真和现场可编程门阵列(FPGA)上的硬件实现及在线实时验证研究,结果表明,该同步方案在低信噪比条件下具有很好的同步性能,可以作为一个完整OFDM基带处理器的子模块实时、连续地对信号进行处理。 展开更多
关键词 正交频分复用(OFDM) 同步捕获 现场可编程门阵列(FPGA) 低信噪比
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月球与深空任务测量船双捕策略研究 被引量:5
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作者 黄磊 沈俊 +2 位作者 程承 陈少伍 李赞 《空间电子技术》 2020年第5期88-93,共6页
在航天任务的发射及早期轨道段,由于有应急指令发送以及定初轨的迫切需求,能否快速、稳定、可靠地完成测量船对目标探测器的双向捕获直接关系到任务的成败。本文介绍了常规地球卫星任务的测量船统一测控设备双捕流程,分析了该流程不适... 在航天任务的发射及早期轨道段,由于有应急指令发送以及定初轨的迫切需求,能否快速、稳定、可靠地完成测量船对目标探测器的双向捕获直接关系到任务的成败。本文介绍了常规地球卫星任务的测量船统一测控设备双捕流程,分析了该流程不适用于后续月球与深空探测任务的原因,并针对我国月球与深空探测器的测控需求和器上应答机特点(由S频段发展为X频段,由模拟应答机发展为数字应答机),分别设计了相应的测量船双向捕获策略,即对模拟应答机采用多普勒预置情况下的三角波扫描法,对数字应答机采用常数多普勒预置法或拐点平滑扫描法。文中提到的策略在我国嫦娥五号任务和首次火星探测任务的天地测控对接试验中得到了充分验证,将在任务中得到实际应用。 展开更多
关键词 测量船 双捕 月球探测 深空探测 测控 策略
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An Anti-Eavesdropping Method in Data Collection of Smart Meter
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作者 Weiwei Dong Yong Wang +2 位作者 Lin Zhou Kanghua Cao Haiming Li 《Journal of Computer and Communications》 2019年第9期38-49,共12页
At present, DL/T 645-2007 communication protocol is used to collect data for smart meters. However, in the beginning, this protocol is not designed to be a secure protocol and only the function and reliability were ta... At present, DL/T 645-2007 communication protocol is used to collect data for smart meters. However, in the beginning, this protocol is not designed to be a secure protocol and only the function and reliability were taken into account. Plaintext is used in the protocol for data transmission, as a result, attackers can easily sniff the information and cause information leakage. In this paper, man-in-the-middle attack was used to verify that the smart meter data acquisition process was vulnerable when facing third-party attacks, and this can result in data eavesdropping. In order to resist such risks and prevent information being eavesdropped, a real ammeter communication experimental environment was built, it realized two-way identity authentication between data acquisition center and ammeter data center. At the same time, RSA (Rivest-Shamir-Adleman) was used to encrypt the meter data, which encrypted the collection, storage process of meter data and ensured the confidentiality and integrity of the meter data transmission. Compared with other methods, this method had obvious advantages. The analysis showed that this method can effectively prevent the data of smart meters from being eavesdropped. 展开更多
关键词 Smart METER Data acquisition Transmission EAVESDROPPING RSA two-way AUTHENTICATION
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