频率转换

As walk-off angle and acceptance angle of beam limit the conversion efficiency and the tunable wavelength range of difference frequency generation, research include effective nonlinear coefficient, walk-off angle and acceptance angle as functions of wavelength, the relationship between conversion efficiency and acceptance angle, and the impact of crystals length on the process of frequency conversion.

由于光束的走离角、允许角限制了转换效率和差频调谐波长范围，研究内容还涉及了有效非线性系数、走离角和允许角与波长的关系，转换效率与允许角的关系，以及晶体长度在频率变换过程中产生的影响。

The waves cause the tip to vibrate, and when the frequency of the incoming wave matches the resonance frequency of the tube, the device can convert the transmission into an audible signal.

电波引起末端振动，当接收的电波频率与管共振频率相配，该装置就能把波形转换成音频信号。

Information of system auto and cross spectrum, auto and cross correlation. coherent function, signal to noise ratio, frequency response and impulse response was established to help the study and arrangement of the module components.

由力规及加速规两量测之时域讯号，经快速富利叶转换，计算其自频谱及互频谱，再经反富氏转换回时域之自相关及互相关函数、相通函数、讯噪比、频率响应函数、脉冲响应函数。

The definition and transformation relationship of natural frequency, bandwidth fre quency and dualˉten index frequency were studied.

文中研究了转台自然频率、带宽频率和双十指标频带的定义与相互转换关系。

There are two types — heterodyne converters and those which use frequency multiplication principles.

共有两种转换方式，即外差转换器以及那些使用频率乘法原理的转换方式。

Adopting discrete time-domain method to set up the mathematical model of high-voltage conversion circuit, and analyzing the influence of frequency, duty cycle, primary inductance, different turns ratio parameters how to affect high-voltage convertion circuit charging time.

采用离散时域方法建立高压转换电路数学模型，分析了高压转换电路频率、占空比、原边电感量以及匝比等设计参数对高压转换电路充电时间的影响，并进行了仿真和实验验证。

It is composed of six parts: PCI Bus interface module, signal generator, signal adjustor, gain and phase detector, A/D conversion module and control and data process module. The system can measure the gain and phase curves of the crystal with the frequency range from 1MHz to 150 MHz. Crystal parameters can also be calculated, such as resonant frequency, series resistance, shunt capacitance, motion capacitance, motion inductance and Q factor, etc.

该测试卡以 IEC 444 标准为测量原理，由 PCI 总线接口模块、信号发生器、信号调理模块、增益相位检测电路、A/D 转换模块等部分组成，能够有效测量 1MHz～150 MHz 频率范围的晶振的增益与相位特性、串并联谐振频率、等效电阻、动态电容、动态电感、品质因数和负载频率等主要电参数。

The digital users signals comprising in-phase component and quadrature component are converted to analog baseband signals by digital-to-analog converters 104 and 114, which are followed by lowpass filters 106 and 116 for removing harmonics at unwanted frequencies.

包括同相分量和正交分量的数字用户信号通过数模转换器104和114转换成模拟基带信号，在数模转换器104和114的后面具有低通滤波器106和116，低通滤波器106和116用于去除在不期望频率处的谐波。

Its final target is to fully digitize the analogue receiver. The all digital receiver not just means digitizing every unit of the analogue receiver, but is a new receiver architecture. The two outstanding characters of this new architecture is: 1 It uses a high stable oscillator to generate a fixed frequency source. And both the sample signal and the local carrier required are obtained from it. 2 Once the received signal has been sampled by a high speed A/D converter, some digital signal processing algorithms will be used to realize all further processes, such as digital down-converting, match filtering, symbol timing, channel equalizing, carrier synchronizing, demodulating and decoding.

全数字接收机并不是简单地将传统的模拟接收机中所有的部件数字化的结果，而是一种全新的接收机体系结构，这种新的体系结构具有两个最为突出的特点：1）采用高稳定度晶体振荡器产生一个固定的本地频率源，接收机中所需的采样时钟信号和本地载波均从这一固定频率源得到；2）接收信号一旦经过高速模数转换后，余下的工作如频率变换、匹配滤波、定时同步、信道均衡、载波同步、符号解调、判决与译码等全部由数字信号处理算法来实现。

Keyboard function set through waveform type,frequency,amplitude,duty cycle,and other parameters of a signal to the microprocessor 89C51 control,MAX038 generated by the various signals,In this process,four-channel signal through D/A converters have simulated voltage and current,It transported up through the analog signal amplification,it enters the frequency MAX038 coarse-IIN,fine-tuning FADJ end,the duty cycle control-DADJ. In its COSC port received a three relays and oscillation frequency capacitance as a choice.

通过键盘设定函数波形种类、频率、幅度、占空比等参数的一个信号进入单片机89C51控制，由MAX038产生各种波形信号，在此过程中信号通过四通道D/A转换器产生模拟电压和电流，它再通过运放将模拟的信号放大，它进入MAX038的频率粗调端IIN、微调端FADJ、占空比控制端DADJ、在它的COSC端口接一个继电器和三个振荡电容作为频率选择。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。