A system scheme of digital image collection plus spread spectrum communication ( abbreviated as ssc ) is presented in this paper after a full analysis of noise characteristics , attenuating characteristics and impedance characteristics of low - voltage power lines 本文首先介绍了低压电力线的噪声特性、衰减特性和阻抗特性，然后提出一种数字图像采集+扩频传输的系统总体方案。
The paper primarily researches a kind of nonlinearity of fiber - the effect of srs ( stimulated raman scattering ) to wdm ( wavelength division multiplexing ) system and the gain and noise properties of fiber raman amplification exploited with srs 本文主要研究了光纤中的一种非线性效应?受激喇曼散射对数字波分复用传输系统性能的影响，以及利用它所开发的光纤喇曼放大器的增益和噪声特性。
In this paper based on the test and simulation of different power networks , the reliability and practicability of carrier communications are discussed and the impedance characteristic , transmission characteristic , the effect of noise on the low - voltage are also analyzed 本文基于对不同电网环境下的载波传输情况进行系统综合测试和仿真的基础上，针对载波通信的可靠性、实用性进行了探讨。分析了低压电力网的阻抗特性、传输衰减特性以及噪声特性影响。
Furthermore , it is also verified by chassis dyno tests that lpg motorcycle has better emission performance than gasoline engine , and has better acceleration performance e . g . exceed acceleration than former gasoline engine , and has low noise level characteristics as well as has ability to achieve equivalent level fuel economy performance compared with former gasoline engine 整车动力性、经济性和排放性转鼓台架试验对比表明： lpg摩托车整体排放性能优于汽油摩托车；最高车速略有下降但加速性基本与汽油摩托车相同(超越加速性优于汽油摩托车) ； lpg摩托车具有良好的低噪声特性，且整车燃料消耗率及其经济性与原机基本相当。
We did some analysis about the relativity between the vibration and the noise of the wheel . after the testing of the first line of guangzhou underground , we found that the existing wheel damper has nothing to do with the noise of wheel less than four thousands hz . compared of different contributions of the tread vibration and the web vibration on sound level of railway noise 在实验过程中,改进了对车轮的激振方式,利用单摆激振提高了激振力的精度;实验分析了车轮阻尼器的结构、安装方式及其动力学参数对车轮阻尼器降噪效果的影响;也分析了车轮振动与噪声的相关性;现场测试广州地铁一号线的噪声特性,确定了车轮阻尼器所要控制的频率范围;对比分析不同激振情况下,踏面径向振动与辐板轴向振动对噪声声压级的贡献比例。
The basic operation principle of phase - locked frequency synthesizer and the type of circuits are expatiated systematicly in this paper . the principle of operation on sampling phase detector and some characteristics including the linear tracking and phase noise in phase loop circuits are analyzed deeply . the research is emphased on the theory and design method of circuits in the sampling phase - locked frequency synthesizer . then , the expansion capturing circuit is analyzed and designed for better performance of capturing loop circuits . at last , the loop filter is also analyzed and contrived taking account of effection of additional phase shift by the sampling - holder . the general research on the theory and technology of sampling phase lock in the paper will make a basement for the development of new product 本文系统的阐述了锁相频率合成器的基本工作原理及电路类型；较深入地分析了取样鉴相工作原理及电路、锁相环路的线性跟踪特性和相位噪声特性；重点对取样锁相频率合成器电路理论和设计方法进行了研究；为了改善环路的捕获性能，对扩捕电路进行了分析和设计，并用wewb32软件对电路进行了仿真；考虑到取样保持器的附加相移影响，对环路滤波器进行了分析和设计。
Take integrity of object information into condition , a two - dimension signal processing method which can make a measurement of the target ’ s speed as well as the range is brought forward at the basis of waveform parameter design . and simulation in the background of hf multi - object with noise is taken . a comparison of signal properties , processing and antinoise detection performance is taken between mcpc and another two high range resolution radar signals : single carrier pulse coded signal and step frequency pulse coded signal 考虑到目标信息提取的相对完整性,以高频雷达为背景,在对多载波相位编码脉冲串信号参数设计的基础上,推导了三种多载频相位编码脉冲串信号的距离速度二维处理过程并相应的对多目标噪声环境进行了仿真;将多载波相位编码信号与另外两种距离高分辨信号:单载频相位编码信号和相位编码阶梯跳频信号,在信号特性、处理过程和抗噪声特性方面进行了对比;本文从理论上为多载波相位编码信号的波形设计和分析、信号的处理打下基础。
Aiming at the scheme of the signal electromagnetic environment simulator of the wireless communication system , the mission of this project is to design and realize twenty - four frequency synthesizers , which must meet high expectation for the phase noise characteristic and the spurious repression characteristic of the output clock signal . these frequency synthesizers provide the moving of the basic signal generating modules to radio frequency with stable inspiring source 本课题的任务是针对通信信号电磁环境模拟器系统的方案要求，设计实现24个(频率分布在260mhz 1430mhz之间)对输出时钟信号的相位噪声特性、杂散抑制特性等要求都很高的频率合成器，为基本信号生成模块到射频的搬移提供稳定可靠的激励源。
This dissertation does research on the algorithm of the complex background and noises compression in ir images as well as its real time system design and implement . the main contents of the dissertation are as follows : 1 . this dissertation advances a efficient algorithm which is used for background and noise suppression based on wgos according to analyzing and studying real ir images 本文研究了在复杂背景下红外图像的背景和噪声抑制算法,并且完成了硬件实现,主要包括以下内容: 1 .通过对实际红外图像的背景和噪声特性的研究分析,设计改进了一种基于加权广义次序统计滤波器的背景抑制的算法。
This paper designs a measurement system and measures the main properties of power line practically . the characteristics of power line are analyzed in detail , and a power line channel model is presented which consists of the parametric transfer function model and the simulating model of background noise , narrow noise and impulse noise . simultaneously the simulating method on the computer is presented 本文设计了一个测量系统对实际电力线信道的主要特性进行了测量，详细分析了电力线的信号传输特性和噪声特性，给出了一个实用的室内电力线信道模型，包括参数化的传输函数模型以及背景噪声、窄带噪声和脉冲噪声的近似模型，并给出了计算机仿真实现方法。
