频率调制

It is a combination of the pulse amplitude modulation and frequency modulation types.

该仪器系统是由脉冲幅度调制和频率调制两种遥测系统复合组成的。

In view of universality, function generator with the core of high speed MCU uses the chips of DDS and FPGA. On the basis of generating routine sine wave, it can modulate signal frequency and range. At the same time function generator can generate binary PSK and ASK signal.

考虑到通用性，信号发生器以高速单片机为核心，利用DDS芯片和FPGA，在产生常规正弦波的基础上，还可以对信号进行频率调制和幅度调制；同时还能产生二进制PSK、ASK信号。

Their vocal quality is better than non-passerine, but still much less than oscine passerine. Compared with non-passerine, they appeared longer syllable length, higher basic frequency and more viable frequency ranges. Though the amplitude modulation properties enhanced their vocal production, the type of syllable is still stable and less of variety. So thephrase consisted of syllables are comparatively few and changes of the tone are relatively less.

且表现出很强的频率调制特性和特有的幅度调制特性，相对的音节时程比较长，基频较高且频率变化范围较大，所特有的幅度调制特性更增加了其控声的能力，但其音节的种类仍很单一，缺乏变化，由音节所组成的句型较少，音调变化幅度不大，因此，其叫声质量尽管较非鸣禽有所改善，但相对鸣禽而言却又远远不如。

And various limiting factors are analyzed. It is found that the stability is mostly limited by the noise of photodetector and frequency modulation in the experiment. Several methods of improved stability are also presented here.

从理论上定性分析了频率稳定度受到的各种限制因素，最后得出本实验中频率稳定度主要受频率调制和探测器噪声限制的结论，同时给出了提高频率稳定度的方法。

The calls of non-passerine are some kinds of monotonous dull vocalizations with the characteristics of low and deep frequency, single syllable, low basic frequency and with no ability of modulation in frequency and amplitude. Most of the calls are monotonous and low quality mainly based on the basic song. Compare the vocal of sub-oscine passerine with non-passerine, they have some similar aspects, but the former possesses of stronger capability of vocal control.

非鸣禽的叫声低沉而单调，音节种类单一，基本音频率低，缺乏频率调制以及幅度调制的能力，叫声的品质因数很低，不悦耳，大多为以基本音为主的单音调低音品叫声，亚鸣禽的叫声与非鸣禽近似，但在控声能力方面又有所提高。

If the frequency of a laser is modulated sinusoidally, the first harmonic component of saturated absorption signal can be used as error signal to stabilize the frequency of the laser.

对激光器进行频率调制，检测原子分子饱和吸收信号中的一次谐波成分得到频率误差信号，反馈控制可以实现激光频率的稳定。

Based on the theory of frequency modulation,the principle that frequency jittering spreads the spectrum energy of the voltage and current is analyzed.

针对传统的固定频率PWM控制方式引起的波形频谱能量集中、谐波幅值较大的缺点，文章基于频率调制的理论分析了开关频率抖动技术扩散电压频谱以及电流频谱能量的基本原理，结合传统的PWM控制器，采用三角波作为调制信号实现简单的频率抖动的方法。

Switching Power Supply has three kinds of control circuits: Pulse Width Modulation, Pulse Frequency Modulation, Pulse Width and Frequency Modulation.

开关电源有三种控制方式：脉冲宽度调制、脉冲频率调制、脉冲宽度频率调制。

Make signal be called binary system numeral to make for the make of binary system signal, the binary system make and is divided into a binary system to move key to control(2 ASK), the binary system Pin move key to control(2 FSK), the binary system mutually move key to control(2 PSK) with bad cent the binary system mutually move key to control(2 DPSK) etc. variety basic type, this topic main is numeral the frequency make and call Pin to move key to control.

调制信号为二进制信号的调制称为二进制数字调制，二进制调制又分为二进制幅移键控（2ASK）、二进制频移键控（2FSK）、二进制相移键控（2PSK）和差分二进制相移键控（2DPSK）等多种基本的类型，本课题主要是数字频率调制又称频移键控。

Common AM, with bilateral, residual sideband and single sideband modulation, and so is the amplitude modulation of a few typical examples, and frequency modulation modulation in the point of view is widely used.

常见的调幅、双边带、残留边带和单边带等调制就是幅度调制的几个典型实例；而频率调制就是角度调制中被广泛采用的一种。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。