姓名:高炜班级：通信工程2班学号：10021340208
Atmospheric Laser Communication
Key words: Atmospheric laser communication Modulation Transmit Receive Application Abstract：
Atmosphere Laser communication is one of new communication technologies，as a result of many advantages such as large message capacitances ，the best confidentiality and simple equipment and so on，which would trigger a revolution of new communication technology. The purpose of this paper is to explore the elements of the atmospheric laser communication，advantage and disadvantage of laser communication .
Main text：
There has been tremendous technical advancement of available components such as
laser/LED transmitter, high sensitivity optical receiver offering extremely high bandwidth, efficient modulation techniques, improvement in low power consumption, weight, and size. In spite of many such technological developments, the major limitation of free-space laser communication (lasercom) performance is the atmosphere. Atmospheric condition ultimately determines the laser communications systems performance not only of terrestrial applications but also for uplink-downlink (e.g., between ground and satellite, aircraft or UAV terminals), because a portion of the atmospheric path always includes turbulence and multiple scattering effects.
Atmospheric laser communication technology is a new technology appeared recently .The element of the new technology is that optical signal carrier transmits the signal point to point or point to points by atmosphere. This technology use semiconductor laser as the optical source，which forms a communication system named digital radio communication system. Laser communication system include two parts：Transmittal and Reception. Transmittal contains Lasers, optical modulator and optical emitting antenna. And reception contains the optical receiving antenna, optical filet and optical detector. The messages we need to transmit connect to lasers in optical modulator and optical modulator modulates the messages to laser and transmitted by the optical emitting antenna. At the receiving end, the optical receiving antenna receives laser signal and send the signal to optical detector. The optical detector transforms the
laser signal to electrical signal and demodulates electrical signal to original messages after amplification.
The primary factors characterizing an atmospheric communication channel include atmospheric attenuation (from both scattering and absorption) and scintillation. Attenuation of the optical wave (i.e., reduction of its power) by atmosphere can be caused in several ways, including absorption of light by gas molecules and Rayleigh or Mie scattering by gas molecules or aerosol particles suspended in the air. Optical transmission spectrum of the U.S. Standard Atmosphere over the various communication windows is available in the literature. [1] The individual absorption lines are caused by the vibration-rotational absorption lines of water vapor, CO2, CH4, and other gases of minor constituents in the atmosphere. Scattering from aerosols and particulates such as in fog, clouds, smoke, and dust also contribute to the total attenuation Of the optical beam.
1、The component of atmospheric laser communication system
Atmospheric laser communication system consists of two communication mechanism，which transmit modulated laser pulse signal（voice or data） reciprocally，receiving and demodulating the signal emitted by each other，achieving duplex communication.
a)Optical maser
Optical maser generates laser signal and forms beam into space. The quality of optical maser directly influences the communication quality and communication distance. It can cause great effect to system performance.
b)Modulator and Modulation method
Modulation is that adding signal into signal carrier. Modulation is a kind of photoelectric converter, which is a process that one parameter (intensity, frequency, phase position, polarization .etc) of output beam changes with electrical signal ，finishing modulation of laser. The modulation methods have internal modulation and external modulation. The internal modulation is that adding the electrical signal modulated by information signal into laser，making laser transmits light signal changed with information signal. The external modulation is that putting the modulation units out of the light source and adding the electrical signal modulated by information signal into modulation crystal. When light beam through the crystal, one parameter (intensity, frequency, phase position, polarization .etc) changes with the electrical signal changing. Then it becomes light signal contained information. Regardless of internal
modulation or external modulation, every modulation method has its own different modulation forms such as Pulse amplitude modulation, pulse width modulation and pulse frequency modulation. In addition, directly modulation also contains pulse code modulation and external modulation contains Amplitude modulation, frequency modulation, pulse code modulation, polarization modulation and so on.
2、Transmitter and Receiver System
There are several atmospheric transmission windows within the 700–10,000-nmwavelength range that has attenuation of <0.2 dB/km and so are nearly transparent. The majority of free-space lasercom systems are designed to operate in the windows of 780–850 and 1520–1600 nm.Around 850 nm, reliable, inexpensive; high-performance transmitter and detector components are readily available. These are often used in network and transmission equipment. Highly sensitive silicon (Si) avalanche photodiode (APD) and an advanced vertical-cavity surface-emitting laser (VCSEL) are available for operation near 850 nm. For the wavelength range of 1520–1600 nm, high quality transmitter and detector components are also readily available. InGaAs is the most commonly used detector material for this longer wavelength; it exhibits high bandwidth capability combined with a high spectral response. This material is extremely sensitive because of an internal amplification (avalanche) process. These wavelengths are also suitable with erbium-doped fiber amplifier technology for high-power generation (>500 mW) and high-data rate (>2.5 Gbit/s). This wavelength region is also important from a laser eye safety point of view. The American National Standard for Eye Safe Use of Lasers Institute (ANSI) standards for the maximum permissible exposure level (MPE) for a 10-sec exposure is about 1 mW/cm2 for an 800-nm wavelength and about 100 mW/cm2 for a 1550-nm wavelength. The longer wavelength system is thus readily designed to be eye safe. Other benefits of the 1550-nm wavelength region include a reduced solar background and reduced scattering attenuation, because of the Rayleigh dependence of inverse wavelength to the fourth power.
a)Optical receiving system
Optical receiving is a process that collecting light signal modulated from the distance by optical lens, a process that filter filtrate wave, a process that photoelectric detector takes photoelectric conversion. There are two approaches to receive. One is direct detection reception and another is heterodyne detection reception. Direct detection reception is a process that making light signal transfer into electrical signal by Optical system and optical detector. It’s a kind of a way simple and practical. As GaAs laser communication is the direct detection receiver, which has disadvantage is the low sensitivity, signal-to-noise ratio. The principle of heterodyne
detection reception is similar to heterodyne detection of Radio wave .As shown in Fig 1, optical system received the laser signal frequency is f c,through the filter and selectively reflecting mirror to the optical mixer photosensitive surface, at the same time the vibration generated by the laser frequency is F0 of the laser through the mirror is reflected into the mixer photosensitive surface. The mixer is a photoelectric detector, it is on two superimposed wave detecting and mixing, output difference frequency F M = F0 -F C Intermediate frequency signal, the F M center frequency band-pass filter into electric signal. This kind of reception has qualities of High sensitivity, signal-to-noise ratio, but the equipment is complex and technical is difficult.
Fig. 1 Heterodyne detection schematic diagram
b)Atmospheric transmission technology
Climates conditions have great influence in laser transmission, light decay very fast. This is mainly due to atmospheric gases and aerosol molecular "scattering" caused "absorption". The main influent factors affected the nature of light are CO2, oxygen smoke, dust, water droplets and borneol. In the lower atmosphere most of the water combines with in form of water, representing atmospheric volume 4%.At the same time the propagation of light also is influenced by the weather, which makes the atmospheric visibility variation.
3、Link Analysis
The overall system performance of a lasercom is quantified using a link budget derived from the range equation, which combines attenuation and geometrical aspects to calculate
the received power. The process of finding the link margin through the system link calculation is the topic of this section. The purpose of this section is to develop the parameters necessary to calculate the performance of an optical communication link. We shall consider the situation of optical propagation between points in free-space. Consider a laser transmitter antenna with gain GT transmitting a total power PT at the wavelength. The signal power received at the communications detector can be expressed (from the range equation) as
Received Signal, PREC = PTGT τT τATMSGRτR,
Another important parameter in optical communications link analysis is “Link Margin”, which
is the ratio of available received power to the receiver power required to achieve a specified BER at a given data rate. Note that the “required” power at the receiver P REQ (watts) to achieve a given data rate, R (bits/sec), and receiver sensitivity, Nb (# photons/bit), is related by P REQ = NbRhν= NbRhc/λ, where νis the frequency of the laser light of wavelength (h = Planck’s constant, c = velocity of light). The parameter Nb is usually defined as receiver sensitivity and can be expressed as # photons/bit, or in dBm (taking the logarithm to the base 10 and multiplied by 10 with base as 1 mW). Finally, we can define the link margin M as
M = Received Power/Required Power.
Combining the above equations yields the expression
M = [P T /(N b Rhν)](D2/θ2T L2)τT 10(?αL/10)τR.
4、The advantage and disadvantage of atmospheric laser communication technology
a)The advantage of atmospheric communication
The main advantage in communicating, i.e., transferring information from one point to another, with optical frequencies is the potential increase in information transfer rate. This rate is directly related to the bandwidth of the modulated carrier, which is generally limited to a fixed fraction of the carrier frequency itself. Therefore, increasing carrier frequency from that of, say, RF or microwaves to that of optical waves increases the information capacity of a communication system by many orders of magnitude. A usable bandwidth at an optical frequency of ～200 THz will be about 105 times that of a carrier in the RF range. A second advantage of using optical frequencies is the station compactness it allows. A 6-inch-diameter lens “antenna” for use with an optical frequency of 6 ×1014 Hz has an effective gain of 122 dB. At an RF frequency of 1 GHz to generate about 60 dB gain, it would require an antenna with a diameter of over 200 feet. This is due to the fact that the beam divergence is roughly proportional to λ/D, where λis the carrier wavelength and D is the aperture diameter, and varies inversely with antenna gain. Thus, a longer wavelength necessitates a proportionately larger antenna to achieve the same gain
First, laser communication has large messages capacitances, in theory, laser communication can transmit 10000000 TV programs and 10000000000 telephones. Second, laser communication has the strangest confidentiality, Not only the direction of the laser is especially strong, but also can be used without visible light, so it is not easy to be intercepted by the enemy, it has good secrecy performance. Third, the equipment of atmospheric laser communication is light and inexpensive, Because of the divergence angle of laser beam is small, and good directivity, laser communication required for transmitting antenna and the receiving
antenna can be very small, general antenna diameters is a few centimeters and a few kilograms of weight, meanwhile the weight of similarity microwave antenna is several tons, more than 10 tons. Because of these advantages, optical carrier frequencies can accommodate very high data rates of 100 GHz or more. With the advent of the new technology of wavelength division multiplexing (WDM), we can further increase the data rate per optical beam. As optical technology matures the advantages of practical free-space laser communications systems can be realized with much architecture.
b)The disadvantage of atmospheric laser communication
First, atmospheric attenuation is very serious. Atmospheric and climate have great influence in laser transmission .cloud, rain and dust will prevent the propagation of laser. These elements affect the communication distance seriously. Second, it‘s hard to aiming at reception equipment. Laser beam has highly directivity; it takes a lot of difficult to aim between transmission point and reception point. Not only demand the high equipment stability and accuracy of the proposed, but also the complex operation.
5、The application of atmospheric laser communication in military
In 1989, the United States of America successfully developed a short distance, concealed in the atmospheric laser communication system. And in 1990, another success of the atmospheric laser communication, the ultraviolet light wave communication, that using in special warfare and low intensity warfare was finished by researchers. At the beginning of the 1990s, with its high power semiconductor laser device developed, Russian also started the atmospheric laser communication system study on applied technology. Subsequently, he launched a new type of semiconductor laser atmosphere communication system, and in Moscow, Tula, Waluonieshen city can be used. The experts generally think that laser atmosphere communication system in a certain distance is possible to effectively achieve all-weather communication; it has potential wealth of the military. Compare with optical communication, the cost of the atmospheric laser communication technology is lower than traditional communication technology and optical communication technology. It’s very fast in practical application, especially suitable for quick grab. The atmospheric laser communication technology also has the strong point such as safe operation, less susceptible to eavesdropping; removable, upgrade etc. Therefore, the laser atmospheric communication can greatly improve the communication ability. Laser atmospheric communication applied in military field is very wide. It can stand in the alpine completed between the border posts and forest observed communication; it can solve the temporary necessary erected communication and computer networking or a mobile switching station; it
can be mounted on the coast, rivers, islands, or ship to realize short distance communication. At the same time, it’s convenient and security.
Conclusion
In this paper， I have introduced simply the structure and form of the atmospheric laser communication and the key equipment of the system, and some application of the new technology. But this is a new technology; what’s more, this technique has a lot of technology that has not been breached.In short, from now, we should pay more attention to the new technology Atmospheric Laser Communication.
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馈控制系统，根据一定的算法分析该信号，判断信号及干扰到达的方位角度，将计算分析所得的信号作为天线阵元的激励信号，调整天线阵列单元的辐射方向图、频率响应及其它参数。利用天线阵列的波束合成和指向，产生多个独立的波束，自适应地调整其方向，跟踪信号变化，对干扰方向调零，减弱甚至抵消干扰，从而提高接收信号的载干比，改善无线网基站覆盖质量，增加系统容量。 多波束天线利用多个并行波束覆盖整个用户区，每个波束的指向是固定的，波束宽度也随天线元数目而确定。随着用户在小区中的移动，基站相应选择不同的波束，使接收信号最强。自适应天线阵列一般采用4～16天线阵元结构，阵元间距为半个波长。天线阵元分布方式有直线型、圆环型和平面型。自适应天线阵列是智能天线的主要类型，可以完成用户信号接收和发送。该系统采用数字信号处理技术识别用户信号到达方向，并在此方向形成天线主波束。自适应天线阵列中，各天线元的放置形式可有多种，相邻天线元间距为一特定值。在接收信号到达天线阵时，每个阵元上的信号经过不同的加权，然后再叠加产生一个输出信号，加权系数和叠加可以根据不同的准则。 为了使智能天线具有良好性能，应根据具体的电波传播环境，选择相应的智能算法。采用软件无线电技术使系统具有良好的改善能力，提高系统性能。 3 智能天线的优点 智能天线可以从以下几个方面明显改善无线通信系统的性能，提高系统的容量：
通信一班序号：28 姓名：粟清明学号：14102301239 JXTA is a crystallization by Sun company's chief scientist Bill Joy's more than twenty years of brewing."JXTA technology is a platform for Network programming and calculation.To solve the modern distribution calculation especially peer-to-peer (Peer to Peer, P2P) in the calculation of the problem". [1] JXTA research project,which will provide a new framework that make the user more convenient to access to connect on the Internet's personal computer resources, thus further expand Internet 's space. At the same time JXTA is also the Sun's "ONE Internet" strategic continuance, and will take a more positive attitude to compete with the .net strategy of Microsoft and Hailstorm plan . JXTA agreement defines a set of six agreement based on XML, the organization of node into node group, release and found some resources, communication and mutual monitoring provides standardized method. (Endpoint Routing Protocol,ERP) is used for node found routing.To send a message to other nodes, and through the potential firewall and connection. (Rendezvous Protocol,RVP) s used for the nodes in the group to spread information.(Peer Resolver Protocol,PRP) is Used to one or more points to send general inquiries, and receive the response of inquiries. (Peer Discovery Protocol, PDP) is used to release and found advertising resources. (Peer Information Protocol, PIP) used to get other nodes state Information. (Peer Binding Protocol, PBP), can let a node with another node or between more nodes to set up virtual communication channel or pipeline. Compared to the nowadays general communication mode .P2P has many advantages, but it also has a lot of problems waiting to be solved.Firstly, each Peer in P2P is an active participant,in order to make the network performance increase, they need more Peer's participation, so that will result in the network's huge, manage this network will is a complex project; Secondly, P2P agreement compares with traditional
第一课 土木工程学土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。 土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。他们也建造私有设施，比如飞机场，铁路，管线，摩天大楼，以及其他设计用作工业，商业和住宅途径的大型结构。此外，土木工程师还规划设计及建造完整的城市和乡镇，并且最近一直在规划设计容纳设施齐全的社区的空间平台。 土木一词来源于拉丁文词“公民”。在1782年，英国人John Smeaton为了把他的非军事工程工作区别于当时占优势地位的军事工程师的工作而采用的名词。自从那时起，土木工程学被用于提及从事公共设施建设的工程师，尽管其包含的领域更为广阔。 领域。因为包含范围太广，土木工程学又被细分为大量的技术专业。不同类型的工程需要多种不同土木工程专业技术。一个项目开始的时候，土木工程师要对场地进行测绘，定位有用的布置，如地下水水位，下水道，和电力线。岩土工程专家则进行土力学试验以确定土壤能否承受工程荷载。环境工程专家研究工程对当地的影响，包括对空气和地下水的可能污染，对当地动植物生活的影响，以及如何让工程设计满足政府针对环境保护的需要。交通工程专家确定必需的不同种类设施以减轻由整个工程造成的对当地公路和其他交通网络的负担。同时，结构工程专家利用初步数据对工程作详细规划，设计和说明。从项目开始到结束，对这些土木工程专家的工作进行监督和调配的则是施工管理专家。根据其他专家所提供的信息，施工管理专家计算材料和人工的数量和花费，所有工作的进度表，订购工作所需要的材料和设备，雇佣承包商和分包商，还要做些额外的监督工作以确保工程能按时按质完成。 贯穿任何给定项目，土木工程师都需要大量使用计算机。计算机用于设计工程中使用的多数元件（即计算机辅助设计，或者CAD）并对其进行管理。计算机成为了现代土木工程师的必备品，因为它使得工程师能有效地掌控所需的大量数据从而确定建造一项工程的最佳方法。 结构工程学。在这一专业领域，土木工程师规划设计各种类型的结构，包括桥梁，大坝，发电厂，设备支撑，海面上的特殊结构，美国太空计划，发射塔，庞大的天文和无线电望远镜，以及许多其他种类的项目。结构工程师应用计算机确定一个结构必须承受的力：自重，风荷载和飓风荷载，建筑材料温度变化引起的胀缩，以及地震荷载。他们也需确定不同种材料如钢筋，混凝土，塑料，石头，沥青，砖，铝或其他建筑材料等的复合作用。 水利工程学。土木工程师在这一领域主要处理水的物理控制方面的种种问题。他们的项目用于帮助预防洪水灾害，提供城市用水和灌溉用水，管理控制河流和水流物，维护河滩及其他滨水设施。此外，他们设计和维护海港，运河与水闸，建造大型水利大坝与小型坝，以及各种类型的围堰，帮助设计海上结构并且确定结构的位置对航行影响。 岩土工程学。专业于这个领域的土木工程师对支撑结构并影响结构行为的土壤和岩石的特性进行分析。他们计算建筑和其他结构由于自重压力可能引起的沉降，并采取措施使之减少到最小。他们也需计算并确定如何加强斜坡和填充物的稳定性以及如何保护结构免受地震和地下水的影响。 环境工程学。在这一工程学分支中，土木工程师设计，建造并监视系统以提供安全的饮用水，同时预防和控制地表和地下水资源供给的污染。他们也设计，建造并监视工程以控制甚至消除对土地和空气的污染。他们建造供水和废水处理厂，设计空气净化器和其他设备以最小化甚至消除由工业加工、焚化及其他产烟生产活动引起的空气污染。他们也采用建造特殊倾倒地点或使用有毒有害物中和剂的措施来控制有毒有害废弃物。此外，工程师还对垃圾掩埋进行设计和管理以预防其对周围环境造成污染。
第一课现代数字设计及数字信号处理 课文 A: 数字信号处理简介 1.什么是数字信号处理？ 数字信号处理，或DSP，如其名称所示，是采用数字方式对信号进行处理。在这种情况下一个信号可以代表各种不同的东西。从历史的角度来讲，信号处理起源于电子工程，信号在这里意味着在电缆或电话线或者也有可能是在无线电波中传输的电子信号。然而，更通用地说，一个信号是一个可代表任何东西--从股票价格到来自于远程传感卫星的数据的信息流。术语“digital”来源于“digit”，意思是数字（代可以用你的手指计数），因此“digital”的字面意思是“数字的，用数字表示的”，其法语是“numerique”。一个数字信号由一串数字流组成，通常（但并非一定）是二进制形式。对数字信号的处理通过数字运算来完成。 数字信号处理是一个非常有用的技术，将会形成21世纪的新的科学技术。数字信号处理已在通信、医学图像、雷达和声纳、高保真音乐产生、石油开采等很广泛的领域内引起了革命性的变革。这些领域中的每一个都使得DSP技术得到深入发展，有该领域自己的算法、数学基础，以及特殊的技术。DSP发展的广度和深度的结合使得任何个人都不可能掌握已发展出的所有的DSP技术。DSP教育包括两个任务：学习应用数字信号处理的通用原则及学习你所感兴趣的特定领域的数字信号处理技术。 2.模拟和数字信号 在很多情况下，所感兴趣的信号的初始形式是模拟电压或电流，例如由麦克风或其它转换器产生的信号。在有些情况下，例如从一个CD播放机的可读系统中输出的信号，信号本身就是数字的。在应用DSP技术之前，一个模拟信号必须转换成数字信号。例如，一个模拟电压信号，可被一个称为模数转换器或ADC的电路变换成数字信号。该转换器产生一系列二进制数字作为数字输出，其值代表每个采样时刻的输入模数转换设备的电压值。 3.信号处理 通常信号需要以各种方式处理。例如，来自于传感器的信号可能被一些没用的电子“噪声”污染。测心电图时放在病人胸部的电极能测量到当心脏及其它肌肉活动时微小的电压变化。信号也常会被来自于电源的电磁干扰所影响。采用滤波电路处理信号至少可以去掉不需要的信号部分。如今，对信号滤波以增加信号的质量或抽取重要信息的任务越来越多地由DSP技术完成而不是采用模拟电路完成。 4.DSP的发展和应用 数字信号处理的发展起源于60年代大型数字计算机进行数字处理的应用，如使用快速傅立叶变换（FFT）可以快速计算信号的频谱。这些技术在当时并没有被广泛应用，因为通常只有在大学或者其它的科研机构才有合适的计算机。 由于当时计算机很贵，DSP仅仅局限于少量的非常重要的应用。先驱们的探索工作主要集中在4个关键领域：雷达和声纳，用于保卫国家安全；石油开采，可以赚大量的钱；空间探索，其中的数据是不能重复产生的；及医学图像，可以救治生命。 20世纪80年代到90年代个人电脑的普及使得DSP产生了很多新的应用。与以往由军方或政府的需求驱动不同，DSP突然间由商业市场的需求驱动了。任何认为自己能在这个飞速发展的领域赚钱的人都会立即成为DSP供应商。DSP通过在移动电话、CD播放器及语音邮件等产品中应用进入了公共应用领域。 这些技术革命是自上而下发生的。在20世纪80年代早期，DSP是电子工程专业的研究
档号：专业代码： 广东理工职业学院顶岗实习报告 系别工程技术系 学生姓名xxx 学生学号xxxx 学生班级10通信技术（1）班 专业名称通信技术 校内指导教师xx 校外指导教师xxx 实习单位xx 2013年4月26日
档 2013年4月26日 目录 一．实习单位介绍 (3) 1.广东超讯通信技术股份有限公司 (3) 二. 实习岗位及主要内容 (4) 1.实习目的 (4) 2.思想和纪律表现 (4) 3.实习岗位（管线割接员、管线，设备录入员） (4) 4.岗位要求及主要工作内容 (4) 三. 实习的主要过程 (5) 1、 autoCAD 以及 zwCAD的使用和看竣工图纸 (6) 2、管线割接 (7) 3、做管线割接方案传输设备工程搬迁、割接工作流程 (8) 4、做管线割接方案 (12) 5、OLT (13) 5、施工现场查勘 (14) 四. 实习总结 (16) 参考文献 (16) 致谢 (16) 附录 (16) 顶岗实习记录表及顶岗实习考核鉴定表················
一、实习单位介绍 1.XXXXX股份有限公司 XXX公司成立于 1998 年，是中国最早从事移动通信网络建设、网络维护、网络优化的公司之一，现已成长为集通信软硬件、系统集成、信息技术服务 一体的高科技企业。目前除在广州设有总部外，还在北京、广州、深圳、广西、 江西、四川、甘肃、内蒙古、海南、湖南、贵州等地建立了省级分公司及研发中心。 公司具备通信信息网络系统集成甲级资质、通信网络代维甲级资 质，已通过高新技术企业、软件企业、安全生产企业、ISO（ISO 9001 质量管理体系， ISO14001 环境管理体系、职业健康安全管理体系）等一系列资格认证。 成立至今，公司已经在通讯行业建立了稳定的市场基础和用户支持群体，并逐渐成为通信技术服务规范的发起者和倡导者。 公司充分发挥自身优势，不断完善、创新服务体系，为中国移动等运营商提供专业、优质的一体化服务。我们的合作伙伴有：中国移动、中国 电信、中国联通。 公司践行“每一比特都精雕细琢”的企业宗旨，秉承“客户、 员工、社会、资本共同获益”的经营理念，自主开发，勇于创新，致力于成为最 优秀的通信技术服务商。 超讯成立于 1998 年，是中国最早从事移动通信网络建设、网络维护、网络优化的 公司之一，现已成长为集通信软硬件、系统集成、信息技术服务一体的高科技企业。目前除在广州设有总部外，还在北京、广州、深圳、广西、江西、四川、
摘要 通信工程（Communication Engineering）专业是信息科学技术发展迅速并极具活力的一个领域，尤其是数字移动通信、光纤通信、Internet网络通信使人们在传递信息和获得信息方面达到了前所未有的便捷程度。通信工程具有极广阔的发展前景，也是人才严重短缺的专业之一。本专业学习通信技术、通信系统和通信网等方面的知识，能在通信领域中从事研究、设计、制造、运营及在国民经济各部门和国防工业中从事开发、应用通信技术与设备。毕业后可从事无线通信、电视、大规模集成电路、智能仪器及应用电子技术领域的研究，设计和通信工程的研究、设计、技术引进和技术开发工作 Communication Engineering (Communication Engineering major is information and the rapid development of science and technology and a dynamic field, especially digital mobile communications, optical fiber Communication, Internet, network Communication makes people in the passing information and access to information has reached unprecedented convenience degree. Communication engineering has a very broad prospects for development, is also one of the serious shortage of professional talents. This professional learning communication technology, communication system and network knowledge, can in the field of communication research, design, manufacture, operation, and in the departments of national economy and defence industry engaged in the development and application of communication technology and equipment. After graduation can be engaged in wireless communications, television, large scale integrated circuit, intelligent instrument and application in the field of electronic technology research, design and communication engineering research, design, technology import and technology development work。 关键词： 前言： 在现代社会，经济高速发展，社会日益前进，广阔的经济前景离不开通信的发展。近几十年，全球通信迅猛发展，走在时代前沿。目前，现代通信已由原先单纯的信息传递功能逐步深入到对信息进行综合处理，如信息的获取、传递、加工等各个领域。特别是随着通信技术的迅速发展，如卫星通信、光纤通信、数字程控交换技术等的不断进步，以及卫星电视广播网、分组交换网、用户电话网、国际互联网络等通信网的建设，通信作为社会发展的基础设施和发展经济的基本要素，越来越受到世界各国的高度重视和大力发展。 在现代社会，通讯技术起到了关键作用。科学技术是第一生产力，既然是生产力，就会对社会的方方面面有决定作用。当然在强调技术对社会的决定作用时，不能片面地夸大技术的作用。技术不能简单的、直接的、唯一的决定社会生活。技术是整个社会大系统的组成部分，与社会的经济、政治、文化和社会生活紧密相关。特别是当今的高技术，它对社会经济、对社会生活质量、对社会关系的改变、对社会政治和社会文化，都有其决定性的作用和影响。马克思把科学技术首先看成是历史的有力杠杆，看成最高意义上的革命。他在评价近代技术的社会作用时说，蒸汽、电力和纺织机甚至是比巴尔贝斯、拉斯拜尔和布朗基诸位公民，更危险万分的革命家。列宁对科学技术的社会作用也给予了极高的评价，在他看来，技术进步“也是其他一切进步的动力，前进的动因”。 而通信技术在对社会发展及社会生活的方面，也存在着巨大作用。通信技术作为信息技术的重要组成部分，共同使人类进入了虚拟时代、数字时代。虚拟，就其本身来说，是数字化方式的构成，它是人类中介系统的革命。虚拟性激发了人们创造能力的巨大发展。通信技术的进步还改变了人们的某些生活方式。比如：过去人们要上邮局寄信，现在在家发个E-mail
一、二、 十一、汉译英时分多址：TDMA （Time Division Multiple Address/ Time Division Multiple Access）2、通用无线分组业务：GPRS General Packet Radio Service 3、国际电报电话咨询委员会：CCITT 4、同步数字体系：SDH Synchronous Digital Hierarchy （同步数字序列） 5、跳频扩频：FHSS frequency hopping spread spectrum 6、同步转移模块：STM synchronous transfer module 7、综合业务数字网：ISDN Integrated Services Digital Network 8、城域网：MAN Metropolitan Area Network 9、传输控制协议/互联网协议：TCP/IP Transmission Control Protocol/Internet Protocol 10、服务质量：QOS Quality of Service 11、中继线：trunk line 12、传输速率：transmission rate 13、网络管理：network management 14、帧结构：frame structure 15、移动手机：Mobile Phone 手机 Handset 16、蜂窝交换机：（Cellular switches）（电池开关cell switch）(cell 蜂房) 17、天线：Antenna 18、微处理器：microprocessor 19、国际漫游：International roaming 20、短消息：short message 21、信噪比：SNR(Signal to Noise Ratio) 22、数字通信：Digital communication 23、系统容量：system capacity 24、蜂窝网：cell network（cellular network）（Honeycomb nets） 25、越区切换：Handover 26、互联网：internet 27、调制解调器：modem 28、频谱：spectrum 29、鼠标：Mouse 30、电子邮件：electronic mail E-mail 31、子网：subnet 32、软件无线电：software defined radios 33、网络资源：network resources 十二、英译汉 1、mobile communication：移动通信 2、Computer user：计算机用户 3、Frame format：帧格式 4、WLAN：wireless local area network 无线局域网络 5、Communication protocol：通信协议 6、Transmission quality：传输质量 7、Remote terminal：远程终端 8、International standard：国际标准 9、GSM：全球移动通信系统 Global System for Mobile Communications 10、CDMA：码分多址Code Division Multiple Access 11、ITU：国际电信联盟 International Telecommunication Union 12、PCM：pulse code modulation 脉冲编码调制 13、WDM：波分复用Wavelength Division Multiplex 14、FCC：联邦通信委员会 Federal communications commission 15、PSTN：公用电话交换网 Public Switched Telephone Network 16、NNI：网络节点借口Network Node Interface 17、WWW：万维网World Wide Web 18、VOD：视频点播Video-On-Demand 19、VLR：访问位置寄存器 Visitor Location Register 20、MSC：移动交换中心Mobile Switching Centre 21、HLR：原籍位置寄存器Home Location Register 22、VLSI：超大规模集成电路 Very Large Scale Integrated Circuits 23、Bluetooth technology：蓝牙技术 24、Matched filter：匹配滤波器 25、ADSL：非对称数字用户环路Asymmetrical Digital Subscriber Loop非对称数字用户线路(Asymmetric Digital Subscriber Line) 26、GPS：全球定位系统Global Position System 27、ATM：异步传输模式Asynchronous Transfer Mode
Building construction concrete crack of prevention and processing Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword: Concrete crack prevention processing Foreword Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and
Unit 13 Comparison between GSM and CDMA GSM与CDMA之比较 Using CDMA/FDD technology, subscribers of CDMA cellular mobile communication system can transmit their information simultaneously through the same channel. On the other hand, the GSM system adopts TDMA/FDD method to transmit and distinguish information from different GSM mobile stations. In addition, in favor of QCELP arithmetic, RAKE receiver, power control and soft switching etc., CDMA shows more advantages in its system performance than the GSM, such as greater anti-interference capability, bigger system capacity, higher successful connection ratio, fewer off-line chances, low probability of intercept(LPI), and so on. 使用码分多址/频分双工技术，用户的蜂窝移动通信系统的传输信息的同时，通过同样的渠道。另一方面，该系统采用时分多址/频分双工传输的方法和识别信息从不同的移动台。此外，有利于中国电信集团广州研发中心算术，耙式接收器，功率控制和软开关等，显示出更多的优势在码分多址系统性能比，如更高的抗干扰能力，更大的系统容量，连接成功率较高，离线的机会少，低截获概率（低截获概率），等。 1, Power Control and RAKE Receiver功率控制和瑞克接收机 When different subscribers send their information to the same BS(base station), different signal power caused by different transmitting distances will consequentially cause interference with each other, especially for those MSs(mobile station) being far away from BS will be seriously disturbed because of their almost submerged signals by signals of the close-to-BS MSs.[2] p110 In order to solve this problem and keep high system performance, power control technique is introduced in CDMA communication system, which can effectively overcome this cross-disturbance. As one of the core techniques in CDMA cellular mobile communication system, power control can make the signal power from all subscribers to the BS equivalent through adjusting the transmitting power from each subscriber. 为解决这一问题，保持较高的系统性能，功率控制技术介绍了码分多址通信系统，它可以有效地克服这cross-disturbance。作为一个核心技术在蜂窝移动通信系统的功率控制，可以使信号功率从所有用户的学士学位相当于通过调整发射功率，从每个用户。 Power control can be not only divided to open-loop control and closed-loop control, but also to forward (down) power control and backward (up) power control. For open-loop control method, subscriber adjusts emitting power according to the measured frame error probability, while for the closed-loop power control, base station measures the signal-to-noise ratio of received signals and then adjust the transmitting power of corresponding MS. 功率控制不仅可以分为开环控制和闭环控制，而且还提出了（下）功率控制和反向功率控制（上）。开环控制方法，用户调整发射功率根据测量帧错误概率，同时为闭环功率控制，基站测量接收信号的信噪比，然后调整发射功率相应的女士 The backward power control in CDMA system can be divided into two kinds of control technique, the open-loop backward power control only used by mobile station, and the closed-loop
电子与通信工程前沿技术 系列讲座结课论文 姓名：XXX 学号：XXXXXX 院系：XXXXXX 指导老师：XXXXXX 电子与通信工程前沿技术系列讲座结课论文 第一讲先进信号处理理论及在无线通信、多媒体等领域中的应用 这次报告主要讲了四方面的内容：分数阶傅里叶变换、压缩感知理论框架、无线通信系统信号处理领域和多媒体信号与信息处理领域。陈老师结合分数阶傅里叶变换理论及压缩感知理论，介绍了这些先进信号处理理论的发展研究状况，并通过实例给出了相关理论在无线通信和多媒体领域中的应用研究。接着，他讲述了自己主持的国家自然科学基金以及郑州大学与北京理工大学等院校联合在研的国家自然科学基金重点项目的研究进展。 第二讲未来通信技术——认知无线电与协作通信 穆晓敏讲课的主要内容有：当前频谱利用现状、静态频谱分配的瓶颈及解决方案以及当前遇到的问题，同时还向我们介绍了互联网+、智慧城市、人工智能（AI)、工业4.0、
DT时代等相关内容。 认知无线电技术已经向“网络与系统”的框架转变，为增强认知能力、降低认知成本，协作手段成为必然。物理层链路技术面临进一步提升性能的“瓶颈”，通过不同网络元素间的多维度协作提高系统整体性能是下一阶段移动通信系统增强的主要途径。在这一过程中，对环境背景信息和用户业务特征的广泛感知是智能化协作与联合资源管理的重要基础。认知无线电与多维度协作通信的结合将成为技术发展的必然趋势。 第三讲智能可穿戴设备概念、基于纺织纤维的可穿戴式产品 文老师主要向我们介绍了智能可穿戴设备的概念以及文老师所创建公司研发的基于纺织纤维的可穿戴产品。 智能可穿戴设备是应用穿戴式技术对日常穿戴进行智能化设计、开发出可以穿戴的设备的总称，如眼镜、手套、手表、服饰及鞋等。最早的可穿戴设备用于军事、户外运动、人体检测等。苹果手表、微软手环和谷歌眼镜是当前最热门的智能穿戴设备，国内也涌现出大量的可穿戴智能设备厂商，像小米手环等。 在不久的将来，智能可穿戴设备将成为人体的一部分，就像皮肤、手臂一样。在更远的未来，手机可能只需向人体植入芯片，而Siri将能直接通过对话帮你打电话，帮你订餐馆，了解你的一切隐私，跟你的亲密程度甚至超过你的家人——可能谷歌眼镜和苹果手表都不再是植入人体的芯片了，他们已经成为人体基因的一部分，可以参与人类的繁衍和进化。 第四讲嵌入式系统的开发
通信工程专业英语翻译 JXTA is a crystallization by Sun company's chief scientist Bill Joy's more than twenty years of brewing."JXTA technology is a platform for Network programming and calculation.To solve the modern distribution calculation especially peer-to-peer (Peer to Peer, P2P) in the calculation of the problem".[1] JXTA research project,which will provide a new framework that make the user more convenient to access to connect on the Internet's personal computer resources, thus further expand Internet 's space. At the same time JXTA is also the Sun's "ONE Internet" strategic continuance, and will take a more positive attitude to compete with the .net strategy of Microsoft and Hailstorm plan . JXTA agreement defines a set of six agreement based on XML, the organization of node into node group, release and found some resources, communication and mutual monitoring provides standardized method.(Endpoint Routing Protocol,ERP) is used for node found routing.To send a message to other nodes, and through the potential firewall and connection.(Rendezvous Protocol,RVP) s used for the nodes in the group to spread information.(Peer Resolver Protocol,PRP) is Used to one or more points to send general inquiries, and receive the response of inquiries.