频率转换

A modified schmitt trigger based relaxation oscillator is used to convert thermistor and hygrometer resistances into a frequency signal .

在前端运用基于施密特触发器为基础的松弛振荡器把温、湿度传感器的电阻值转换为频率的信号，从而把温度和湿度的变化转变为数字电路可以处理的频率信号的变化。

Through this experiment,it was measured that average diameter of the fundamental frequency light is 2.33 mm in the pattern of ordinary krypton pump,while in he pattern of the laster- diode bar pump the average diameter is only 1.25 mm,and the light field of the later also took on the standard Gaussian distribution,therefore formed the high-bright...

通过实验测量到普通氪灯泵浦方式中基频光的平均直径为2.33 mm，LD 阵列对称泵浦方式中基频光的平均直径仅为1.22 mm，并且呈现标准的高斯分布，形成了高亮度激光输出。实验研究了 Nd：YAG 调 Q 固体激光器的重复频率对 KTP 倍频晶体转换效率的影响。并且，在基频光平均功率11.2 w时，经 KTP 晶体倍频产生5.11W 的532 nm 绿光输出，光-光转换效率达到45.6%。

To support these clock rates, a reasonable solution is to clock the ADC and DAC at a fixed master clock rate and perform sample rate conversion completely in digital domain.

为了支援这些标准，比较合理的作法是让类比转数位和数位转类比转换器工作在固定的频率，利用数位的作法改变取样频率以支援不同的通讯协定。

We expect it will benefit the industry field to break through the optical measuring limits at present by offering some new ideas. Optical measuring research based on moire interferometry has developed for several decades. The main idea of this research is to utilize the moire effect caused by two superimposed gratings of identical or similar spatial frequency. One is the reference grating and it is a virtual grating created by a computer program in this research; The other grating is the image of grating projected on the measured surface by the DLP projector, and this grating will distort because of the different sloped profile of the surface. To superimpose the program-created grating and the captured distorted grating will derive the so-called moire effect. This research combined the basic theory of optical interferometry and moire effect to project the different phases of the projected grating fringes by the phase-shifting method and compute the principal value of arguments between -π,π. In the end, the phase unwrapping program based on discrete Fourier transform of solving PDEs is used to unwrap the phase of the measured surface, and finally the surface profile is derived by the optical measuring system.

以叠纹干涉术为基础的光学检测研究之发展早已行之有年，而在本研究中所采用的投影叠纹法(Projection moiré)之主要精神在於藉由两道空间频率相近或相同的光栅相互叠加而成的效应，其中一道为参考光栅，而本研究中的参考光栅是以程式产生可调整不同空间频率的虚拟光栅；另一道则为投影至待测物表面的光栅影像，而在起伏高度不一的待测表面上的光栅影像会受到待测物表面起伏状况不同而在观测方向产生光栅投影条纹影像的歪曲变形，将电脑产生的参考光栅与由影像撷取装置所获取投影於待测物表面的光栅影像作叠合，便会产生所谓的叠纹效应；利用基本的光学干涉理论与叠纹效应结合，本研究中以相移法来改变投影於待测表面的光栅相位，再以相移法的理论反运算出在带有待测面各点高度资讯之介於-π，π相位主幅角，再以离散傅立叶转换解偏微分方程的相位重建程式还原待测面的相位值，以得知待测面之表面轮廓。

A new way of distance measurement is introduced in this paper, it is similar to traditional measurement way, and has its origination. In the new measurement way, the rough measurement of the distance is realized by countering high frequency pulses filled in discriminable phase pulses. Discriminable phase pulses go through integral circuits, and then are sampled by Analogue Digital Converter, so the accurate measurement of the system is obtained by the sampling value.

本文提出了一种新的测距方法，该方法与常规相位测距仪比较，既有相似之处也有其创新之处，常规相位测距仪一般使用多波长测尺频率组合、差频数字测相的方法，本系统虽然也采用多波长测尺频率组合，但并不采用差频数字测相，该方法摒弃了传统的内外光路的切换方式及电路的混频，粗测采用对鉴相脉冲填充高频脉冲的办法实现，精测则利用鉴相脉冲对积分电路进行积分，然后由ADC 对积分电平进行转换，通过对ADC 的输出值的计算处理实现精测。

7 To 3.3 V operating supply voltage 44.1 kHz sampling frequency 16.9344 MHz (384fs) system clock Built-in crystal oscillator circuit 16-bit, MSB rst, rear-packed serial data input format ( 64 fs bit clock) 8-times oversampling digital lter · 32 dB stopband attenuation ·+0.05 to -0.05 dB passband ripple Deemphasis lter operation · 36 dB stopband attenuation ·-0.09 to +0.23 dB deviation from ideal deem- phasis lter characteristics Attenuator · 7-bit attenuator (128 steps) set by microcontrol- ler Soft mute function set by parallel setting ·(approximately 1024/fs total muting time) Mono setting · Left or right channel mono selectable by micro- controller Built-in innity-zero detection circuit , two-channel D/A converter · 3rd-order noise shaper · 32fs oversampling Built-in 3rd-order post-converter low-pass lters 24-pin VSOP package Molybdenum-gate CMOS process

2.7至3.3 V工作电源电压为44.1千赫的采样频率16.9344兆赫（384fs）系统时钟内置晶体振荡器电路的16位，MSB在前，后包装的串行数据输入格式（64飞秒位时钟）8倍超采样数字滤波器·32分贝的阻带衰减·+0.05至-0.05分贝通带纹波去加重滤波器的运作·36 dB抑制频宽衰减·-0.09到0.23 dB的偏差认为不理想，症状困扰评估滤波特性衰减器·7位衰减器（128级）集由单片机在-莱尔软静音功能的平行设置·（共约1024/fs静音时间）单声道设置·左或右声道单声道微控制器可选的内置的无限零检测电路Δ，两通道的D / A转换器·第三阶噪声整形·32fs过采样内置三阶后转换器的低通滤波器24引脚VSOP封装钼栅CMOS工艺

In this topic, the dynamic analysis methods for piezoelectric vibrator are studied systematically based on the theoretical model, FEM numerical experimentation and FEM governing equation for given compound-mode vibrator, and some valuable conclusions are obtained. The main work accomplished is summarized as follows: 1.Elaborate the main modeling methods for piezoelectric vibrator and the significance and necessity to study the dynamic characteristics of piezoelectric vibrator which emphasize the urgency of this paper. 2.Take the bending deformation induced by piezoelectric ceramic as example, the energy transfer mechanism of electric energy to mechanical energy are analyzed; the motion and force transfer mechanism are analyzed for the longitudinal-bending vibrator. 3.Based on mode assumption and Hamilton principle, the coupling model of piezoelectric vibrator of linear USM is built; moreover, the equivalent circuit model is obtained and a coupling equation represents the relation between electric parameters and mechanical parameters is derived which provides foundation to match the vibrator and driving circuit. 4.Combine the constitutive equation of piezoelectric ceramic with elastic-dynamical equation, geometric equation in force field and the Maxwell equation in electric field and the corresponding boundary condition equation, the FEM control equation for piezoelectric vibrator of USM to solve dynamic electro-mechanical coupling field is established by employing the principle of virtual displacement. The equation lays the foundation to study the non-linear constitutive equation of piezoelectric ceramic driven by high-power. 5.Define the dynamic indexes of characteristic of vibrator and carry out variable parameters simulation by calculating the model parameters and the electric characteristics of vibrator are simulated according to the equivalent circuit model. By numerical experimentation, the working mode of vibration of vibrator and the shock excitation results of the working frequency band which provides the mode frequency to realize bimodal are analyzed. Detailed calculation of the electro-mechanical coupling field parameters is made by programming the FEM control equation.

本课题从理论模型、有限元数值试验、有限元控制模型等方面以复合振动模式振子为例对超声电机压电振子的动力学特性及其分析方法进行了全面系统地研究，得出了许多有价值的结论，主要概括如下： 1、阐述了目前针对超声电机压电振子的主要建模方法，对压电振子动态特性的研究意义和必要性进行了论述，突出了本文研究内容的迫切性； 2、以压电陶瓷诱发弹性体发生弯曲变形为例，分析了压电陶瓷通过诱发应变来实现机电能量转换的机理；对基于纵弯模式的压电振子的运动及动力传递机理进行了分析； 3、基于模态假定，利用分析动力学的Hamilton原理，建立了面向直线超声电机压电振子的机电耦合动力学模型，并据此建立了压电振子的等效电路模型，导出了电参量与动力学特性参量的耦合方程，为压电振子与驱动电路的匹配提供了依据； 4、从压电陶瓷的本构方程出发，综合力场的弹性动力学方程、几何方程、电场的麦克斯韦方程以及相应的边界条件方程，采用虚位移原理，建立了压电振子动态问题机电耦合场求解的有限元控制方程，为研究其大功率驱动下的非线性本构模型奠定了基础； 5、界定压电振子的动力学特性指标，对压电振子的机电耦合动力学模型参数进行计算及变参数仿真；依据等效电路模型，对压电振子的电学特性进行了仿真分析；通过有限元数值实验，对压电振子工作模态附近的模态振型及工作频率附近的频段进行了激振效果分析，找出了实现模态简并的激振频率；利用有限元控制方程，通过编程计算，对压电振子的力电耦合场参数进行了详细计算，得出了一些有价值的结论。

Methods: The precise frequency of RMF is controlled by using microcomputer to drive step motor, and intensity of magnetic field is measured by using 10-bit Analog-to-Digital Converter module which is integrated in microcomputer. According, the technique of LCD screen to display relative information, such as, frequency, intensity of magnetic field, time of timer, is applied.

采用高性能单片机实现精确地控制进电机的转速，从而达到控制旋转磁场的频率，并利用其内带的10位A/D转换实现对磁场强度的测量，同时利用LCD显示旋转的频率、磁场强度、定时时间等信息。

The relationships between the frequency characteristics of type Ⅱ servosystem and dynamic performances are studied. An approch to dynamic design of RDC is proposed and experimental results have demonstrated that this dynamic design method is effective.

从动态分析的角度出发，文中导出了跟踪型轴角数字转换器的动态数学模型，探讨了典型Ⅱ型伺服系统频率特性与跟踪性能指标的关系，进而给出了转换器的动态参数设计方法。

Using triple integral equation based on scalar Green function for forward modeling transient electromagnetic response to a 3 D anomalous body, a frequency response of electromagnetic field component has been evaluated first on frequency domain, then the evaluated results has been transformed into time domain by using fast numeric filtering algorithm.

用基于张量格林函数的体积分方程对三维异常体进行瞬变电磁响应的正演模拟，首先在频率域内计算电磁场分量的频率域响应；然后利用快速数字滤波技术将计算结果转换到时间域。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。