一种非均匀采样系统采样均匀性的评价新方法

提出了在多A/D合成采样系统中采样均匀性的评价方法;通过使用正弦波激励系统,将各个子A/D的数据分别抽取形成子抽样序列,使用最小二乘正弦波曲线拟合法,获得各个子抽样序列初始相位间的差异,该差异对应的时间差即为各个子A/D间的采样延迟时间,它们的一致性就是系统的采样均匀性。在一组仿真数据上验证了方法的正确性。在数字存储示波器的实测数据上进行了实验验证,获得了有效的测量结果,验证了方法的可行性。该方法可以用来评价非均匀采样系统的采样均匀性。     

非均匀采样信号的数字频谱分析

本文介绍了一种近年来发展起来的非均匀采样信号的基本理论,以及由此推出的非均匀采样信号的数字谱表达式。分析了非均匀采样正弦信号的数字谱及其信噪比。文中还对几种典型的非均匀采样实例进行了分析,推导出其各自的信噪比。     

非均匀采样下Savitzky-Golay算法的研究

简单介绍了均匀采样下Savitzky-Golay滤波与非均匀采样,提出一种基于数据的非均匀采样的Savitzy-Golay算法,并对该算法进行matlab建模验证比较,简要说明了其可行性。     

数字存储示波器时基失真与采样抖动的评价研究

提出了数字存储示波器采样间隔抖动和采样时基失真的一种时域评价方法.通过两段正弦波形段的滑动拟合结果,使用两者间对应点相位上的差异,实现了采样间隔的测量,获得其抖动波形和时基失真的测量结果.在一组仿真数据上进行了实验验证,并揭示了量化误差对抖动评价影响的规律,以及抖动测量结果的周期性变化规律.在数字存储示波器的实测数据上进行了实验验证,获得了有效的抖动波形结果.该方法可以用来观察和比较采样间隔的抖动以及采样时基失真特性.     

基于非均匀周期采样的随机共振研究

随机共振的参数调节过程比较复杂,而且一般要求采样频率不低于信号频率的50倍以上才能实现随机共振。该文借鉴非均匀采样的思想,提出基于非均匀周期采样的随机共振实现方法,对不同采样频率下的采样数据进行随机共振,并利用非均匀采样傅里叶变换进行频谱叠加分析,可以实现只需简单确定随机共振参数即可得到特征信号成分。此种方法还可以在采样频率小于50倍信号频率时,依然能够得到特征信号频率成分。数值仿真和故障模拟实验研究验证了该方法有效的应用性。     

非均匀采样信号的能量/功率测量

本文分析了采样信号的非均匀性对于能量／功率测量的影响，推导了非均匀采样信号在时域与频域上的能量对应关系，得出了利用非均匀采样序列计算信号的能量／功率收敛于真值的条件。仿真结果验证了理论的正确性。     

基于EDFT的非均匀欠采样叶尖定时信号分析

针对叶尖定时信号因严重的非均匀采样和欠采样导致的谱分析难题,提出了基于扩展离散傅里叶变换(EDFT)的分析方法.不同于传统的傅里叶变换,EDFT是以傅里叶积分变换为目标,在扩展的频率范围内通过构造和优化变换基函数替代传统FFT变换中的指数基来实现非均匀和欠采样信号的谱分析,在分析中利用原始数据迭代和近似拟合保证了分析精...     

一种大规模高速并行采样及校正技术研究

采用多ADC并行采样结构是迅速提高数据采集系统实时采样率的重要途径。首先提出了一种大规模并行采集系统的总体方案;然后重点阐述了大规模并行采样技术实现与校正的若干关键技术:高速并行采样时钟的产生技术、并行采样数据触发点定位技术和非均匀采样实时校正技术;最后给出了实验结果与分析。采用上述关键技术的高速数据采集系统具有实现成本低、性能指标可靠、实时性高等优点。     

一类非均匀采样信号的内插重构算法

本针对多路Ａ／Ｄ交替采样存在的采样非均匀现象,分析了此类非均匀采样信号 ,进而推导出其内插重构算法,并通过计算机仿真验证了算法的正确性。该重构算法在工程实际中具有应用价值。     

非均匀采样时带通信号重建像函数的一种计算方法

在广义采样定理的信号模型的基础上,讨论了非均匀采样时带通信号的重建问题,导出了重建函数的傅里叶像的一种有效计算方法,最后给出了带通信号重建的计算机仿真实例。     

另一类幅度非均匀取样信号的数字频谱及补偿算法研究

研究了高速并行数字化系统中由ADC增益的不一致性造成的幅度非均匀取样信号的特点,推导出了这类幅度非均匀采样信号的数字频谱表达式,详细分析了输入正弦信号时的数字频谱,得到了系统的信噪比表达式。提出了一种利用IFFT运算对输出信号的频谱进行重构的补偿方法,计算机仿真验证了该方法的有效性。     

随机矩阵抖动加网在光栅防伪技术中的应用

针对模式抖动加网技术在光栅防伪中的应用问题,通过对阈值矩阵进行改进,提出了在一定范围内随机选择阈值矩阵的模式抖动加网的方式,实现了随机矩阵的模式抖动加网方法在光栅防伪技术中的较好应用。     

对产品抽样检验国家标准的探讨与研究

本文通过对抽样检验标准创立和我国统计抽样检验标准发展历程的深入探讨,以及对我国现行有效抽样检验国家标准主题内容和适用范围的综合分析,阐述了贯彻执行和正确使用抽样检验国家标准的重要性。     

Aperture Jitter of Sampling System in AWGN and Fading Channels

This paper examines aperture jitter of the sampling system and its effect on communication systems in the additive white Gaussian noise (AWGN) and fading channels. Previous studies have claimed that AWGN power is directly proportional to the jitter noise power. We demonstrate that the aperture jitter can influence the input signal of a sampling system but is independent of AWGN. The noise power, due to the aperture jitter in a frequency-nonselective slowly fading channel, is shown to be a function of the input signal, the aperture jitter, and the channel envelope. The frequency-selective slowly fading channel involves another parameter analyzable paths. The effect of the aperture jitter on the bit-error probability (BEP) of a binary-phase-shift-keying digital communication system is also considered. The received signal-to-noise ratio (SNR) is calculated first, and its probability density function is derived. Then, the average BEP is evaluated as a function of SNR. Simulation results indicate that the aperture-jitter noise severely degrades the average BEP by reducing the received SNR. The results of this paper can be used in designing a wideband or radio-frequency-sampling digital communication system     

A Double Sampling Procedure to Control the Variance in Net Weight Acceptance Sampling

This paper describes a double sampling scheme to estimate with at least a given precision the mean of a variate whose variance has two components one of which is unknown. Although the procedure is described almost entirely in terms of a particular problem (quality control of net weight), it may be applied in a more general situation (section 5). The consequences of using either the mean square error or the range to estimate variance are investigated.     

美国食品安全检验局进口产品监控计划

本文详细介绍了美国食品安全检验局(FSIS)国家残留监控计划(NRP)和微生物监控计划对进口肉、禽和蛋产品的监控,研究了进口监控计划抽样方案的准则、方法和不足,以及检测方法、结果报告和应用,为我国进出口食品监控计划的抽样方案的制定提供参考和借鉴。     

基于确定性测量矩阵的心电信号压缩采样算法研究

远程心电监测治疗中心电压缩技术至关重要.论文介绍了压缩采样理论的原理,根据确定性矩阵在压缩采样理论硬件实现上的优势,构造了一种多项式确定性矩阵,与块稀疏贝叶斯框架算法相结合,并在此基础上,对多项式确定性矩阵QR分解进行优化,实验表明:该矩阵可以满足实时高精度重建信号的要求,优化后的矩阵更进一步提高了算法性能.     

Designing and Selection of Mixed Sampling Plan with Chain Sampling as Attribute Plan

This paper deals with the operating procedure of mixed acceptance sampling plans with chain sampling as attribute plan. The operating characteristics function and other associated measures of the plan are provided. The plan is designed through AQL and IQL. Tables are constructed for easy selection of the plan. Illustrations are also provided.     

The Effect of Correlation on Chain Sampling Plans

The Dodge chain sampling plan (ChSP‐1) and its extensions are very useful in situations where testing is either destructive or costly. Its underlying assumption is that all units to be inspected are from the same process and the quality characteristic of interest follows an identical independent distribution. Although this assumption makes the model relatively simple and easy to implement, it may not hold for today's manufacturing processes with high production volume, in which correlation exists between products within the same process. In this paper, we propose a Markov chain model for chain sampling plans to model the dependency (correlation) between testing units. To achieve this, we assume that product units within each sample follow a Markov chain model and assume that they are independent when they are from different lots. The resulting OC curves and AOQ curves show that the discriminating power of chain sampling plans improves when there is a negative correlation between product units and deteriorates when the correlation is positive. Copyright © 2004 John Wiley & Sons, Ltd.