采样误差

This paper utilizes FFT after undersampling to analyze the relationship between the estimation of sinusoidal parameters and corresponding actual values on the basis of bandpass sampling theorem. In addition, the errors of parameter estimation using phase difference are deduced strictly.

摘要该文从带通采样定理出发，分析了欠采样后利用FFT估得的正弦信号参数与真实值之间的关系，并对欠采样下基于相位差分法的参数估计的误差进行了严格的推导。

Simulation results show that, for the fixed sampling frequency, the error rises with the frequency increasing of periodic signal, and decreases with the attenuation time constant increasing of non-periodic signal. The sampling frequency determines the upper limit of appropriate frequency band directly. The research provides the basis for the selection of cutoff frequency in filter design.

仿真结果表明，在采样频率确定时，对于周期信号，计算误差随频率的增加而增大，而对于非周期信号，计算误差随衰减时间常数的增大而减小，采样频率大小决定了插值法用于分布参数模型的适用频带上限，该研究为滤波器设计中截止频率的选择提供了依据。

Under the situation of even distribution of fitting nodes,a mathematic model is established by means of the relation between the number of fitting nodes and the limit error of measurement.

建立了采样点均匀分布情况下，圆度误差测量采样点数量与测量极限误差之间的定量关系数学模型。

Investigation indicates that the error of frequency estimation is proportional to the sampling rate, while that of initial phase independent of it.

研究表明频率估计的误差在采样点数确定时正比于采样率，而初相估计的误差则不受采样率的影响。

According to the division principle of flue gas sampling point in round stack,the paper gives a convenient and prac-tical formula of the dixtance from sampling point to inwall and corrects the errors in table of the distance value from sampling point to in wall in the published literatures.

本文根据圆形烟道采样点划分原则，给出了一种方便适用的采样点距烟道内壁的距离公式，并就现有文献中采样点距烟道内壁的距离值表格的误差进行了修正。

The result shows that the error in sample and quantization causes coupling error in the output of attitude in SINS.

结果表明，由于采样和量化过程中的误差，使惯导系统输出的姿态角出现了耦合误差，并提出了对采样信号进行预处理即设计滤波函数以减小采样信号失真的观点。

ABSTRACT:The half-power bandwidth method is the commonly used method at home and abroad, the authors discover that factors, such as the sampling frequency, the frequency resolution, the ratio of the sampling frequency to the signal frequency, the analyzed width and the damping ratio, make the estimated damping ratio fluctuate vastly. Mostly the result is incredible except for some conditions, the error is sometime amazing, which is not acceptable.

半功率带宽法是国内外常用的测试阻尼的方法，笔者发现半功率带宽法由于受到信号处理中的①采样频率SF②频率分辨率△f③采样频率与信号频率之比K ④采样分析的长度T和⑤阻尼比D的大小等因素的影响使得测得的阻尼比值波动很大，除少数状态是可信的外，多数状态是不稳定的，有时误差惊人，得到的测试数据不能使用，易导致错误的结论。

In the hardware circle design, the original measure signal is gained from the sensor, so it is critical to make a choice; In additional, a new type electronic component called True R MS-to-DC converter AD536A which can reduce the complex and expatiatory software transition is used to improve the system's response speed; This system is controlled by a single chip microcomputer which will processes the sampling signal.

在硬件电路中，由于原始的测量信号是从传感器获得的，因此传感器的选用比较关键。本仪表采用了新型电子芯片AD536，AD536真有效值芯片可以省去复杂冗长的软件换算过程，提高系统的响应速度，在此主要是介绍它的功能和应用特点；我们采用单片机对采样信号进行处理，选用凌阳16位单片机，着重介绍了它的性能特点；在采样和误差分析方面，对测量仪的数据转换系统进行了详细的分析，包括该系统的结构功能以及误差的来源，并提出了提高精度减小误差的措施。

First, sequential tomograms of the hip are obtained from a CT scan; secondly, an accurate and automatic method is used to extract the profile of the acetabulum; thirdly, a hybrid method is utilized to gather fiducial marks on the acetabulum; fourthly, bulky error sampling points are removed. Finally, an ellipsoid fitting method is used to fit the ellipsoid model of the femoral head. Two male sufferers with different necrosis extents are chosen as experimental subjects for contrastive simulation.

首先利用一种精确的自动分割方法在髋骨部位CT序列图像中提取髋臼轮廓；然后使用基于等距栅格采样法与辐条式采样法相结合的混合采样法得到髋臼凹面的空间坐标点集，并剔除其中的误差采样点；最后采用基于二次曲面一般方程的方法拟合原始股骨头椭球面模型。

operation process and arithmetic of the two-position gyro-based north seeker are introduced.

文章介绍了二位置陀螺寻北仪工作过程及算法原理，它采用陀螺仪在相差180°的两点上采样相互对消陀螺常值漂移的方法，提高寻北精度；其突出特点是结构简单，实现方便，精度较好；为了提高寻北精度和缩短寻北时间，文章找出误差源中的转位误差，并分析了转位误差对寻北误差的影响，推导了误差公式，得出转位误差引起的寻北误差是一个常量的结论，同时提出了转位误差的测量与补偿方法。

By the time of its fall, most of the prisoners were writers who had written against the corruptions of the government.

到它被攻陷的时候，里面多数的犯人是写了反对政府贪污文章的作家。

The most obvious variation to ovum morphological character was that the color was changed from light green to sepiaceous in embryonic development, and all the ovums were almost hatched after 96h.

在胚胎发育过程中卵的形态特征最明显的变化是颜色从淡绿到深褐色，卵在发育96h后卵基本全部孵化。