调幅

NTSC uses a quadrature amplitude modulation with a suppressed color carrier and works with amotion frequency of approximately 30 Hz. A picture consists of 525 lines.

NTSC的色彩载波使用接近4.9MHz或3.57MHz的频率，它使用颜色载波进行正交调幅，画面运动频率约为30Hz，每幅画面有525线。

Frequency modulation minimizes noise and provides greater fidelity than amplitude modulation, which is the older method of broadcasting.

调频最大程度的减小噪音，并且比调幅的保真度高，调幅是一种较老的传播方法。

It was also found that no obvious boundary existed between spinodal decomposition and cellular decomposition, the wavelength of spinodal decomposition was 2.16nm.

同时还发现，调幅分解几乎与胞状分解同时发生，二者之间没有明显界限，调幅波长为2.16nm。

After studying the altering direction and amplitude modulation mechanism of this type of reversible vibratory plate compactor,this paper discusses the principle of altering direction ,modulating amplitude and adjusting speed.

研究了平板夯换向调幅机构的结构，在力学分析的基础上，阐述了这一机构调幅、调速和换向机理。

Continuous casting experiments results show that in the mold oscillation coupled with AMMF EMCC, imposition of AMMF duty part during mold oscillation positive strip can deduce the withdraw resistance and improve the billets surface.

论文的第三部分，基于以上的一些研究，提出了又一项新的技术——调幅磁场下无结晶器振动电磁连铸技术，以期用结晶器外调幅磁场电磁力的振动来取代庞大的机械振动系统。

In the third part of the paper, another novel technology, named as Mould Oscillation-less Electromagnetic Continuous Casting under AMMF was proposed in order to replace the huge mechanical mould oscillation system by AMMF imposing outside the mould in continuous casting.

进行了三种波形高频调幅磁场下的无结晶器振动电磁连铸初步实验研究，实验结果表明：在方波、三角波和正弦波调幅磁场作用下的无结晶器振动电磁连铸过程中，当调制波频率略低于系统固有频率时，弯月面与结晶器壁间断接触距离最大。

The system of phase equilibrium data of the Fe-Cu base alloy is established relatively, the spinodal decomposition range of the Fe-Cu base alloy is calculated utilizing Thermo-Calc software, The composition range of the spinodal decomposition of the Fe-Cu base alloy is prognosticated with more accuracy; The self-formed mechanism of egg-type microstructure of the Fe-Cu base alloy with spinodal decomposition in the liquid-phase region under gravity conditions is theoretically investigated. Based on the analysis and calculation of interfacial tensile stress induced by the temperature gradient in the process of solidification, the theoretical results interpret preferably the self-formed mechanism of egg-type microstructure of the Fe-Cu base alloy through the analyzing of force states of metallic droplet in the rapid solidification.

建立了较为完整的铁铜基合金系的相平衡数据体系，利用Thermo-Calc软件对铁铜基合金系的液相调幅分解成分范围进行了计算，较准确地对铁铜基合金系的液相调幅分解成分范围进行了预测；从理论上对液相调幅分解型铁铜合金卵型结构的形成机理进行了研究，基于凝固过程中由温度梯度所导致的界面张力的分析与计算，通过考察快速凝固过程中金属液滴受力情况，较好地解释了液相调幅分解型铁铜合金卵型结构的自形成机理。

modulation is the transmission of information to be loaded onto a high-frequency signal in the process.amplitude modulation using signal to control the rate of carrier,with its linear modulation signal changes,and maintain the same carrier frequency.in the amplitude modulation,in accordance with the strength of signals in the spectrum of different components,it is divided into ordinary am (amplitude modulation standard am),with inhibition of bilateral carrier am,the carrier single sideband suppression am.the main difference is the different methods and structure of the spectrum.

摘 要：调制是将要传送的信息装载到某一高频信号上去的过程。振幅调制是用调制信号去控制载波的幅度，使其随调制信号线性变化，而保持载波的频率不变。在幅度调制中，根据已调信号的频谱分量不同，分为普通调幅、抑制载波的双边带调幅、抑制载波的单边带调幅。它们的主要区别是产生的方法和频谱结构不同。

This chapter also studies the performance of the DPSD algorithm based on cross correlation when detecting AM signal, presents the improvements to it based on the study. The improved DPSD algorithm can be used to measure the amplitude of the AM signal.

本章还研究了被测正弦信号的幅度随时间变化时，第二章中的DPSD算法测量调幅信号的性能，并根据研究结果对其进行了改进，使之能够适应调幅信号的测量。

Time (3Xrpm) turning table speed. In addition, while the teeth of the tri-cone bit interact with the formation, the drillstring will generate tiny axial vibration. As the vibration is symphonious to the tri-spine well bottom, the vibration signal exhibits amplitude modulation character. This character had been verified by in-site measurement data and numerical simulation.

另外，三牙轮钻头与地层作用破岩时牙轮牙齿产生啮合振动，由于三脊状井底对啮合振动进行幅度调制形成调幅信号，根据调幅信号的频率特征，振动信号在频域表现为具有一定边带的一束谱线，它是钻头工作正常的&健康信号&。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。