This paper constructs the probability model of the multi-valued KM_1M_2 clock controlled generator,and discusses the probability distributing,homogeneous Markov property,ergodic property,strict placidity,numeral chara...This paper constructs the probability model of the multi-valued KM_1M_2 clock controlled generator,and discusses the probability distributing,homogeneous Markov property,ergodic property,strict placidity,numeral character and the property of large numbers of the random variables with this kind of output sequence.It gets the probability formula of the coincidence of the output sequence with the input sequence,and gives important reference to the design and analysis of the multi-valued key stream clock controlled generator in cryptography.展开更多
In this paper, the mutual information between clock-controlled input and output sequences is discussed. It is proved that the mutual information is a strictly monotone increasing function of the length of output seque...In this paper, the mutual information between clock-controlled input and output sequences is discussed. It is proved that the mutual information is a strictly monotone increasing function of the length of output sequence, and its divergent rate is gaven.展开更多
针对相干布局囚禁(Coherent Population Trapping,CPT)原子钟的比例积分微分(Proportional-Integral-Differential,PID)参数优化问题,提出一种基于神经网络的全局寻优方法。首先通过数学建模模拟CPT原子钟的微波锁定过程,使用数字PID控...针对相干布局囚禁(Coherent Population Trapping,CPT)原子钟的比例积分微分(Proportional-Integral-Differential,PID)参数优化问题,提出一种基于神经网络的全局寻优方法。首先通过数学建模模拟CPT原子钟的微波锁定过程,使用数字PID控制算法实现频率稳定。采用蒙特卡洛方法生成10000组不同PID参数(K_(p),K_(i),K_(d))的系统响应数据,构建包含输入层、两层隐藏层及输出层的全连接神经网络模型,以均方误差(Mean Squared Error,MSE)为性能指标,建立参数与性能的非线性映射关系。试验结果表明,优化后的PID参数(K_(p)=0.4960,K_(i)=0.0054,K_(d)=0.0016)使CPT原子钟的锁定时间从110 s缩短至30 s,提速73%;万秒Allan偏差(Allan Deviation,AD)提升1.5倍,验证了方法的有效性。与传统Ziegler-Nichols方法相比,神经网络通过全局映射避免了局部最优问题,且计算效率提升显著,为CPT原子钟的高性能控制提供了新途径。展开更多
针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现...针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现了硬件时间戳获取,避免了由于协议栈软件处理延时产生的不确定性;针对PTP时钟晶振老化导致的时间同步偏差及网络延迟抖动问题,采用迭代方法优化了本地时钟频率调节算法,提高了频率校正精度。经实际测试,主从时钟偏差的RMS(root mean square)优于20 ns,提升了时钟同步精度。展开更多
随着高清电视和网络媒体的快速发展,音视频同步技术在广播电视节目制作中的重要性日益突出。通过对当前音视频同步系统的分析,深入研究节目时钟参考(Program Clock Reference,PCR)、显示时间戳(Presentation Time Stamp,PTS)/解码时间戳...随着高清电视和网络媒体的快速发展,音视频同步技术在广播电视节目制作中的重要性日益突出。通过对当前音视频同步系统的分析,深入研究节目时钟参考(Program Clock Reference,PCR)、显示时间戳(Presentation Time Stamp,PTS)/解码时间戳(Decoding Time Stamp,DTS)、音视频缓冲区控制等关键技术在实际制作环境中的应用。基于自适应缓冲区控制的音视频同步方案能将音视频延迟控制在±15 ms以内,满足广播级节目制作要求。展开更多
基金Supported by the Computer Network and Information Security Foundation of Ministry of Education Laboratory(20040108)
文摘This paper constructs the probability model of the multi-valued KM_1M_2 clock controlled generator,and discusses the probability distributing,homogeneous Markov property,ergodic property,strict placidity,numeral character and the property of large numbers of the random variables with this kind of output sequence.It gets the probability formula of the coincidence of the output sequence with the input sequence,and gives important reference to the design and analysis of the multi-valued key stream clock controlled generator in cryptography.
文摘In this paper, the mutual information between clock-controlled input and output sequences is discussed. It is proved that the mutual information is a strictly monotone increasing function of the length of output sequence, and its divergent rate is gaven.
文摘针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现了硬件时间戳获取,避免了由于协议栈软件处理延时产生的不确定性;针对PTP时钟晶振老化导致的时间同步偏差及网络延迟抖动问题,采用迭代方法优化了本地时钟频率调节算法,提高了频率校正精度。经实际测试,主从时钟偏差的RMS(root mean square)优于20 ns,提升了时钟同步精度。
文摘随着高清电视和网络媒体的快速发展,音视频同步技术在广播电视节目制作中的重要性日益突出。通过对当前音视频同步系统的分析,深入研究节目时钟参考(Program Clock Reference,PCR)、显示时间戳(Presentation Time Stamp,PTS)/解码时间戳(Decoding Time Stamp,DTS)、音视频缓冲区控制等关键技术在实际制作环境中的应用。基于自适应缓冲区控制的音视频同步方案能将音视频延迟控制在±15 ms以内,满足广播级节目制作要求。
