From theoretical analysis , we know the existing demodulation methods have limitations as following : one is that the subtraction of the two signals frequencies will display as the result of demodulation when we demodulate two time - domain adding signals without modulating information ( fault information ) ; the other one is that aliasing phenomenon will occur as a result of getting absolute value , detection or square in the process of generalized demodulation analysis , such phenomenon will result in some superfluous frequency composition on the frequency spectrum , which will puzzle the detec tion of mechanical vibration . if the sampling frequency is selected from a suitable range , the aliasing phenomenon will be avoided ; the last one is that aliasing frequencies will be produced in zoom demodulation analysis because this algorithm cannot employ digital low - pass filtering to avert the folding frequencies of higher harmonics in the process of zoom sub - sampling 现有的解调分析方法存在以下三种局限性：将不包括调制信息(故障信息)的两时域相加信号，也以其频率之差作为解调信号而解出；广义检波滤波解调分析中，由于取绝对值、检波或平方过程可能产生混频效应，在解调谱中表现为无法分析的频率成分，并由此推导出避免这种混频现象的采样频率的选取范围，从根本上避免此类误诊断的产生；几种细化解调分析新算法中，因为无法在细化分析的选抽时进行数字低通滤波，有可能会出现调制频率的高次谐波成分发生频率混叠而反折到低频部分的现象。
The principle advantages of vcsels over conventional edge - emitting lasers lie in ultralow threshold current , small far - field divergent angle , high modulation frequency , potential for wafer level testing and the ease for single longitudinal mode operation and two - dimension integration . as a result they show considerable promise for applications such as optical fiber communication , parallel optical interconnects , optical information processing and neural networks , etc . a direct coupling theoretical model in quasi - three - dimension for the gain - wave guide vertical - cavity surface - emitting lasers has been created in this paper 它与传统的边发射激光器相比具有更优越的特性，例如，具有极低的阈值、较小的远场发散角、调制频率高、易实现单纵模工作和二维集成，无须解理封装即可进行在片测试等，所以，它被广泛应用于光纤通讯、并行光互联、光信息处理、光神经网络等领域。
Abstract : the experiment about ignition property of solid e nergetic materials was done by laser which was generated by big powerful laser i nstrument - nd : yag . the influence on the ignition property of difference enery , puls e width and different frequency of laser instrument and different webs of the pr opellant . was studied and analyzed which may be used to do further researches for ignition 文摘:使用大功率nd : yag激光器产生的激光，对固体含能材料的激光点火性能进行了实验研究，分析了不同能量、脉冲宽度、调制频率及药粒尺寸等因素对点火特性的影响，为激光点传火系统的研制提供了实验依据。
A comprehensive theory is presented for fm spectroscopy of doppler - broadened molecular iodine absorption lines . the relationship betwcen fm spectroscopy and modulation frequency and modulation index has been studied . the whole circuit for thc frcquency stabilized laser system has been developed 建立了多普勒加宽碘分子线性吸收fm光谱的一般理论，对fm光谱与调制频率和调制度的关系进行了研究；并研制了532nmnd : yvo _ 4 / ktp碘吸收稳频激光器的电路系统；提出了虚拟激光稳频技术的概念。
( 3 ) . the theoretical analysis and the experimental study on an active mode - locked fiber laser are conducted . the harmonic mode - locked pulses of 2 . 5ghz and 5ghz are achieved and the 2 - 4 order rational harmonic mode - locked pulses of 2 . 5ghz are researched in active mode - locked erbium - doped fiber ring lasers ( 3 )对主动锁模光纤激光器进行了理论分析和实验研究,在主动锁模掺铒光纤环形腔激光器中实现了2 . 5ghz 、 5ghz的谐波锁模,并在2 . 5ghz的调制频率下获得了二、三、四阶的有理数谐波锁模脉冲。
Simulations on light intensity are validated by experiments and influence of mechanical dither on gyro frequency stabilization is studied for the first time . then it is point out that the key to improve the precision of frequency stabilization is to choose appropriate modulation frequency based on the frequency spectrum of sharp pulses , which is introduced by mechanical dither . thereafter , experiments of frequency stabilization under different modulation frequencies are made 通过实验验证了光强仿真结果，首次分析了机械抖动对稳频的影响，指出提高机抖陀螺小抖动稳频精度的关键在于：根据机械抖动引入的交流光强尖峰脉冲频谱分布选择合适的调制频率，并给出了不同调制频率的稳频实验结果。
Ts signal input interface into the data buffer . after finishing the data buffer parameters set by synchronous data output signal . on the dvb standard with the base - band formed after channel i , q signals . by the square root of roll - off filter for qam modulation , frequency modulation by the panel set up , qam have had to deal with the final if if interface circuit sent to the rf channel Ts流数据信号经输入接口送入缓存器，缓存器对数据进行整理后按设置参数输出同步数据信号，经符合dvb标准的各种信道处理后形成基带i q信号，经平方根滚降滤波进行qam调制，调制频率由面板设置，已调qam信号最后经中频if接口电路处理送至射频通道。
In this paper they study a position - detecting system based on microprocessor and psd ( position sensitive detector ) . the method is as follows : when the ac - signal from psd which is illuminated by modulated light source passes through an active band - pass analog filter , it filters the ac signal which represents the object light source . then the dc - converter circuit transforms it into dc - signal which is used to calculate the position 这一系统采用的方法是通过对位置敏感探测器psd受到调制目标光源照射后输出的模拟交流信号进行有源带通滤波，提取出代表目标光源的调制频率成份，再将该信号转变为用来参与位置解算的直流信号，然后选用单片机组成硬件电路，对直流信号进行采集处理并与计算机建立通信，把数据送入计算机进行位置解算，分析判别目标光源和psd器件的相对位置。
Secondly , considering the need of frequency stabilization , mdrlg ' s light intensity is simulated . the simulations indicate that sharp pulses are produced in the ac light intensity by mechanical dither . as the pulses have a wide frequency spectrum and range over the modulation frequencies of frequency stabilization , mechanical dither may reduce the precision of frequency stabilization 其次，根据稳频需要对机抖陀螺输出光强进行了仿真，仿真表明机械抖动会在交流光强中引入尖峰脉冲，且尖峰脉冲频谱分布较宽，在小抖动稳频调制频率范围内有功率输出，因而可能降低稳频精度。
