通信工程专业毕业论文中英文资料外文翻译文献
通信类中英文翻译、外文文献翻译
美国科罗拉多州大学关于在噪声环境下对大量连续语音识别系统的改进---------噪声环境下说话声音的识别工作简介在本文中，我们报道美国科罗拉多州大学关于噪声环境下海军研究语音词汇系统方面的最新改进成果。
特别地,我们介绍在有限语音数据的前提下，为了了解不确定观察者和变化的环境的任务(或调查方法)，我们必须在提高听觉和语言模式方面努力下工夫。
在大量连续词汇语音识别系统中,我们将展开MAPLR自适应方法研究。
它包括单个或多重最大可能线形回归。
当前噪声环境下语音识别系统使用了大量声音词汇识别的声音识别引擎。
这种引擎在美国科罗拉多州大学目前得到了飞速的发展，本系统在噪声环境下说话声音系统(SPINE-2)评价数据中单词错识率表现为30.5%，比起2001年的SPINE-2来,在相关词汇错识率减少16%。
1.介绍为获得噪声环境下的有活力的连续声音系统的声音，我们试图在艺术的领域做出计算和提出改善，这个工作有几方面的难点：依赖训练的有限数据工作；在训练和测试中各种各样的军事噪声存在；在每次识别适用性阶段中，不可想象的听觉溪流和有限数量的声音。
在2000年11月的SPIN-1和2001年11月SPIN-2中，海军研究词汇通过DARPT在工作上给了很大的帮助。
在2001年参加评估的种类有：SPIIBM,华盛顿大学，美国科罗拉多州大学，AT&T,奥瑞哥研究所，和梅隆卡内基大学。
它们中的许多先前已经报道了SPINE-1和SPLNE-2工作的结果。
在这方面的工作中不乏表现最好的系统.我们在特性和主模式中使用了自适应系统，同时也使用了被用于训练各种参数类型的多重声音平行理论(例如MFCC、PCP等)。
其中每种识别系统的输出通常通过一个假定的熔合的方法来结合。
这种方法能提供一个单独的结果，这个结果的错误率将比任何一个单独的识别系统的结果要低。
美国科罗拉多州大学参加了SPIN-2和SPIN-1的两次评估工作。
我们2001年11月的SPIN-2是美国科罗拉多州大学识别系统基础上第一次被命名为SONIC(大量连续语音识别系统)的。
本科毕业论文中英文翻译--Wireless-Communications无线通信【范本模板】
Wireless Communications＊byJoshua S。
Gans，Stephen P。
King and Julian Wright1. IntroductionIn 1895, Guglielmo Marconi opened the way for modern wireless communications by transmitting the three—dot Morse code for the letter ‘S’ over a distance of th ree kilometers using electromagnetic waves。
From this beginning，wireless communications has developed into a key element of modern society. From satellite transmission, radio and television broadcasting to the now ubiquitous mobile telephone，wireless communications has revolutionized the way societies function.This chapter surveys the economics literature on wireless communications。
Wireless communications and the economic goods and services that utilise it have some special characteristics that have motivated specialised studies。
First, wireless communications relies on a scarce resource –namely，radio spectrum –the property rights for which were traditionally vested with the state. In order to foster the development of wireless communications (including telephony and broadcasting）those assets were privatised。
通信工程外文资料翻译2篇
南京理工大学毕业设计(论文)外文资料翻译学院（系）：电子工程与光电技术学院专业：通信工程姓名：学号：外文出处：1. IEEE TRANSACTIONS ONANTENNAS AND PROPAGATION,VOL. 53,NO.9, SEPTEMBER 20052. IEEE TRANSACTIONS ONMICROWA VE THEORY ANDTECHNIQUES, VOL. 53,NO.6,JUNE 2005附件：1.外文资料翻译译文一；2.外文资料翻译译文二；3.外文原文一；4.外文原文二；注：请将该封面与附件装订成册。
附件1：外文资料翻译译文一在单封装超宽波段无线通信中使用LTCC技术的平面天线作者：Chen Ying and Y.P.Zhang摘要：此通讯提出了一个使用低温度共烧陶瓷技术的平面天线用于超宽频带（UWB）无线通信的单封装解决方案。
该天线具有一个通过微带线反馈的椭圆形的辐射体。
该辐射体和微带线拥有与其它UWBR电路相同的接地板。
实验结果表明原型天线已达到110.9％的带宽，从1.34到5.43 dBi的增益，宽模式和频率从3到10.6GHz 的相对恒定的群延迟。
更多地还发现，标准化天线辐射功率谱密度基本符合FCCS 对于室内UWB系统的发射限制。
关键词：低温共烧陶瓷（LTCC），平面天线，超宽频带（UWB）。
一、引言现在，发展用于窄范围高速度的无线通信网络的超宽频带（UWB）无线电是一个研究热点。
超宽带无线电利用一个7.5 GHz的超宽带宽来交换信息。
使用这样大的带宽，在使U超宽带无线电发挥它最大的作用上存在一些问题.其中的一个主要问题是用于移植系统的超宽带天线的设计。
好的超宽带天线应具有较低的回波损耗，全向辐射模式，从3.1至10.6 GHz的超宽带宽下的高效率，同时也应当满足FCCS规定的发射限制。
现在已经有一些超宽带天线，如钻石偶极子和互补缝隙天线。
它们已被证明适用于超宽带无线电[1] - [4]。
通信工程毕业设计 外文翻译
东华理工大学长江学院毕业设计外文翻译学生姓名：张伟学号：09323119专业：信息工程系别：信息工程指导教师：谌洪茂职称：讲师二0一三年六月五日OriginalOptical Fiber CommunicationsThe General System Communication may be broadly defined as the transfer of information from one point to another. When the information is to be conveyed over any distance a communication system is usually required. Within a communication system the information transfer is frequently achieved by superimposing or modulating the information onto an electromagnetic wave which acts as a carrier for the information signal. This modulated carrier is then transmitted to the required destination where it is received and the original information signal is obtained by demodulation. Sophisticated techniques have been developed for this process by using electromagnetic carrier waves operating at radio frequencies as well as microwave and millimeter w ave frequencies. However, ‘communication’ may also be achieved by using an electromagnetic carrier which is selected from the optical range of frequencies.An optical fiber communication system is similar in basic concept to any type of communication system.The communication system therefore consists of a transmitter or modulator linked to the information source, the transmission medium,and a receiver or demodulator at the destination point. In electrical communications the information source provides an electrical signal, usually derived from a message signal which is not electrical (e.g. sound), to a transmitter comprising electrical and electronic components which converts the signal into a suitable form for propagation over the trans-mission medium. This is often achieved by modulating a carrier, which, as mentioned previously, may be an electromagnetic wave. The transmission medium can consist of a pair of wires, a coaxial cable or a radio link through free space down which the signal is transmitted to the receiver, where it is transformed into the original electrical information signal (demodulated) before being passed to the destination.However, it must be noted that in any transmission medium the signal is attenuated, or suffers loss, and is subject to degradations due to contamination by random signals and noise, as well as possible distortions imposed by mechanisms within the medium itself. Therefore, in any communication system there is a maximum permitted distance between the transmitter and the receiver beyond which the system effectively ceases to give intelligible communication. For long-haul applications these factors necessitate the installation of repeaters or line amplifiers atintervals,both to remove signal distortion and to increase signal level before transmission is continued down the link.For optical fiber communications system shown in Figure (a) may be considered in slightly greater detail, as given in Figure (b).Fig(a) The general communication system(b)The optical fiber communication systemIn this case the information source provides an electrical signal to a transmitter comprising an electrical stage which drives an optical source to give modulation of the light wave carrier. The optical source which provides the electrical–optical conversion may be either a semiconductor laser or light-emitting diode (LED). The transmission medium consists of an optical fiber cable and the receiver consists of an optical detector which drives a further electrical stage and hence provides demodulation of the optical carrier. Photodiodes (p–n, p–i–n or avalanche) and, in some instances, phototransistors and photoconductors are utilized for the detection of the optical signal and the optical–electrical conversion. Thus there is a requirement for electrical interfacing at either end of the optical link and at present the signal processing is usually performed electrically.The optical carrier may be modulated using either an analog or digital information signal. In the system shown in Figure (b) analog modulation involves the variation of the light emitted from the optical source in a continuous manner. Withdigital modulation,however, discrete changes in the light intensity are obtained (i.e. on–off pulses).Although often simpler to implement, analog modulation with an optical fiber communication system is less efficient, requiring a far higher signal-to-noise ratio at the receiver than digital modulation. Also, the linearity needed for analog modulation is not always provided by semiconductor optical sources, especially at high modulation frequencies. For these reasons,analog optical fiber communication links are generally limited to shorter distances and lower bandwidth operation than digital links.Figure (c) shows a block schematic of a typical digital optical fiber link. Initially, the input digital signal from the information source is suitably encoded for optical transmission. The laser drive circuit directly modulates the intensity of the semiconductor laser with the encoded digital signal. Hence a digital optical signal is launched into the optical fiber cable. The avalanche photodiode (APD) detector is followed by a front-end amplifier equalizer or filter to provide gain as well as linear signal processing and noise bandwidth reduction.Fig(c)A digital optical fiber link using a semiconductor laser source and an avalanche photodiode(APD) detectorFinally, the signal obtained is decoded to give the original digital information. However, at this stage it is instructive to consider the advantages provided by light wave communication via optical fibers in com-parison with other forms of line and radio communication which have brought about the extensive use of such systems in many areas throughout the world.译文光纤通信一般来说把信息从一点传送到另一点就称为通信。
数据通信 毕业论文外文文献英文翻译
郑州轻工业学院本科毕业设计（论文）——英文翻译题目差错控制编码解决加性噪声的仿真学生姓名专业班级通信工程05-2 学号 12院（系）计算机与通信工程学院指导教师完成时间 2009年4月26日英文原文:Data communicationsGildas Avoine and Philippe OechslinEPFL, Lausanne, Switzerlandfgildas.avoine, philippe.oechsling@ep.chAbstractData communications are communications and computer technology resulting from the combination of a new means of communication. To transfer information between the two places must have transmission channel, according to the different transmission media, there is wired data communications and wireless data communications division. But they are through the transmission channel data link terminals and computers, different locations of implementation of the data terminal software and hardware and the sharing of information resources.1 The development of data communicationsThe first phase: the main language, through the human, horsepower, war and other means of transmission of original information.Phase II: Letter Post. (An increase means the dissemination of information)The third stage: printing. (Expand the scope of information dissemination)Phase IV: telegraph, telephone, radio. (Electric to enter the time)Fifth stage: the information age, with the exception of language information, there are data, images, text and so on.1.1 The history of modern data communicationsCommunication as a Telecommunications are from the 19th century, the beginning Year 30. Faraday discovered electromagnetic induction in 1831. Morse invented telegraph in 1837. Maxwell's electromagnetic theory in 1833. Bell invented the telephone in 1876. Marconi invented radio in 1895. Telecom has opened up in the new era. Tube invented in 1906 in order to simulate the development of communications.Sampling theorem of Nyquist criteria In 1928. Shannong theorem in 1948. The invention of the 20th century, thesemiconductor 50, thereby the development of digital communications. During the 20th century, the invention of integrated circuits 60. Made during the 20th century, 40 the concept of geostationary satellites, but can not be achieved. During the 20th century, space technology 50. Implementation in 1963 first synchronized satellite communications. The invention of the 20th century, 60 laser, intended to be used for communications, was not successful. 70 The invention of the 20th century, optical fiber, optical fiber communications can be developed.1.2 Key figuresBell (1847-1922), English, job in London in 1868. In 1871 to work in Boston. In 1873, he was appointed professor at Boston University. In 1875, invented many Telegram Rd. In 1876, invented the telephone. Lot of patents have been life. Yes, a deaf wife.Marconi (1874-1937), Italian people, in 1894, the pilot at his father's estate. 1896, to London. In 1897, the company set up the radio reported. In 1899, the first time the British and French wireless communications. 1916, implementation of short-wave radio communications. 1929, set up a global wireless communications network. Kim won the Nobel Prize. Took part in the Fascist Party.1.3 Classification of Communication SystemsAccording to type of information: Telephone communication system, Cable television system ,Data communication systems.Modulation by sub: Baseband transmission,Modulation transfer.Characteristics of transmission signals in accordance with sub: Analog Communication System ,Digital communication system.Transmission means of communication system: Cable Communications,Twisted pair, coaxial cable and so on.And long-distance telephone communication. Modulation: SSB / FDM. Based on the PCM time division multiple coaxial digital base-band transmission technology. Will gradually replace the coaxial fiber.Microwave relay communications:Comparison of coaxial and easy to set up, low investment, short-cycle. Analog phone microwave communications mainly SSB / FM /FDM modulation, communication capacity of 6,000 road / Channel. Digital microwave using BPSK, QPSK and QAM modulation techniques. The use of 64QAM, 256QAM such as multi-level modulation technique enhance the capacity of microwave communications can be transmitted at 40M Channel 1920 ~ 7680 Telephone Rd PCM figure.Optical Fiber Communication: Optical fiber communication is the use of lasers in optical fiber transmission characteristics of long-distance with a large communication capacity, communication, long distance and strong anti-interference characteristics. Currently used for local, long distance, trunk transmission, and progressive development of fiber-optic communications network users. At present, based on the long-wave lasers and single-mode optical fiber, each fiber road approach more than 10,000 calls, optical fiber communication itself is very strong force. Over the past decades, optical fiber communication technology develops very quickly, and there is a variety of applications, access devices, photoelectric conversion equipment, transmission equipment, switching equipment, network equipment and so on. Fiber-optic communications equipment has photoelectric conversion module and digital signal processing unit is composed of two parts.Satellite communications: Distance communications, transmission capacity, coverage, and not subject to geographical constraints and high reliability. At present, the use of sophisticated techniques Analog modulation, frequency division multiplexing and frequency division multiple access. Digital satellite communication using digital modulation, time division multiple road in time division multiple access.Mobile Communications: GSM, CDMA. Number of key technologies for mobile communications: modulation techniques, error correction coding and digital voice encoding. Data Communication Systems.1.4 Five basic types of data communication system:（1）Off-line data transmission is simply the use of a telephone or similar link to transmit data without involving a computer system.The equipment used at both ends of such a link is not part of a computer, or at least does not immediately make the data available for computer process, that is, the data when sent and / or received are 'off-line'.This type of data communication is relatively cheap and simple.（2）Remote batch is the term used for the way in which data communication technology is used geographically to separate the input and / or output of data from the computer on which they are processed in batch mode.（3）On-line data collection is the method of using communications technology to provide input data to a computer as such input arises-the data are then stored in the computer (say on a magnetic disk) and processed either at predetermined intervals or as required.（4）Enquiry-response systems provide, as the term suggests, the facility for a user to extract information from a computer.The enquiry facility is passive, that is, does not modify the information stored.The interrogation may be simple, for example, 'RETRIEVE THE RECORD FOR EMPLOYEE NUMBER 1234 'or complex.Such systems may use terminals producing hard copy and / or visual displays.（5）Real-time systems are those in which information is made available to and processed by a computer system in a dynamic manner so that either the computer may cause action to be taken to influence events as they occur (for example as in a process control application) or human operators may be influenced by the accurate and up-to-date information stored in the computer, for example as in reservation systems.2 Signal spectrum with bandwidthElectromagnetic data signals are encoded, the signal to be included in the data transmission. Signal in time for the general argument to show the message (or data) as a parameter (amplitude, frequency or phase) as the dependent variable. Signal of their value since the time variables are or not continuous, can be divided into continuous signals and discrete signals; according to whether the values of the dependent variable continuous, can be divided into analog signals and digital Signal.Signals with time-domain and frequency domain performance of the two most basic forms and features. Time-domain signal over time to reflect changing circumstances. Frequency domain characteristics of signals not only contain the same information domain, and the spectrum of signal analysis, can also be a clear understanding of the distribution ofthe signal spectrum and share the bandwidth. In order to receive the signal transmission and receiving equipment on the request channel, Only know the time-domain characteristics of the signal is not enough, it is also necessary to know the distribution of the signal spectrum. Time-domain characteristics of signals to show the letter .It’s changes over time. Because most of the signal energy is concentrated in a relatively narrow band, so most of our energy focused on the signal that Paragraph referred to as the effective band Bandwidth, or bandwidth. Have any signal bandwidth. In general, the greater the bandwidth of the signal using this signal to send data Rate on the higher bandwidth requirements of transmission medium greater. We will introduce the following simple common signal and bandwidth of the spectrum.More or less the voice signal spectrum at 20 Hz ~ 2000 kHz range (below 20 Hz infrasound signals for higher than 2000 KHz. For the ultrasonic signal), but with a much narrower bandwidth of the voice can produce an acceptable return, and the standard voice-frequency signal gnal 0 ~ 4 MHz, so the bandwidth of 4 MHz.As a special example of the monostable pulse infinite bandwidth. As for the binary signal, the bandwidth depends on the generalThe exact shape of the signal waveform, as well as the order of 0,1. The greater the bandwidth of the signal, it more faithfully express the number of sequences.3 The cut-off frequency channel with bandwidthAccording to Fourier series we know that if a signal for all frequency components can be completely the same through the transmission channel to the receiving end, then at the receiving frequency components of these formed by stacking up the signal and send the signal side are exactly the same, That is fully recovered from the receiving end of the send-side signals. But on the real world, there is no channel to no wear and tear through all the Frequency components. If all the Fourier components are equivalent attenuation, then the signal reception while Receive termination at an amplitude up Attenuation, but the distortion did not happen. However, all the transmission channel and equipment for different frequency components of the degree of attenuation is differentSome frequency components almost no attenuation, and attenuation of some frequency components by anumber, that is to say, channel also has a certain amount of vibrationIncrease the frequency characteristics, resulting in output signal distortion. Usually are frequency of 0 Hz to fc-wide channel at Chuan harmonic lost during the attenuation does not occur (or are a very small attenuation constant), whereas in the fc frequency harmonics at all above the transmission cross Decay process a lot, we put the signal in the transmission channel of the amplitude attenuation of a component to the original 0.707(that is, the output signal Reduce by half the power) when the frequency of the corresponding channel known as the cut-off frequency (cut - off frequency).Cut-off frequency transmission medium reflects the inherent physical properties. Other cases, it is because people interested in Line filter is installed to limit the bandwidth used by each user. In some cases, because of the add channel Two-pass filter, which corresponds to two-channel cut-off frequency f1 and f2, they were called up under the cut-off frequency and the cut-off frequency.This difference between the two cut-off frequency f2-f1 is called the channel bandwidth. If the input signal bandwidth is less than the bandwidth of channel, then the entire input signal Frequency components can be adopted by the Department of channels, which the letter Road to be the output of the output waveform will be true yet. However, if the input signal bandwidth greater than the channel bandwidth, the signal of a Frequency components can not be more on the channel, so that the signal output will be sent with the sending end of the signal is somewhat different, that is produced Distortion. In order to ensure the accuracy of data transmission, we must limit the signal bandwidth.4 Data transfer rateChannel maximum data transfer rate Unit time to be able to transfer binary data transfer rate as the median. Improve data transfer rate means that the space occupied by each Reduce the time that the sequence of binary digital pulse will reduce the cycle time, of course, will also reduce the pulse width.The previous section we already know, even if the binary digital pulse signal through a limited bandwidth channel will also be the ideal generated wave Shape distortion, and when must the input signal bandwidth, the smaller channel bandwidth, output waveformdistortion will be greater. Another angle Degree that when a certain channel bandwidth, the greater the bandwidth of the input signal, the output signal the greater the distortion, so when the data transmissionRate to a certain degree (signal bandwidth increases to a certain extent), in the on-channel output signal from the receiver could not have been Distortion of the output signal sent to recover a number of sequences. That is to say, even for an ideal channel, the limited bandwidth limit System of channel data transfer rate.At early 1924, H. Nyquist (Nyquist) to recognize the basic limitations of this existence, and deduced that the noise-free Limited bandwidth channel maximum data transfer rate formula. In 1948, C. Shannon (Shannon) put into the work of Nyquist 1 Step-by-step expansion of the channel by the random noise interference. Here we do not add on to prove to those now seen as the result of a classic.Nyquist proved that any continuous signal f (t) through a noise-free bandwidth for channel B, its output signal as a Time bandwidth of B continuous signal g (t). If you want to output digital signal, it must be the rate of g (t) for interval Sample. 2B samples per second times faster than are meaningless, because the signal bandwidth B is higher than the high-frequency component other than a letter has been Road decay away. If g (t) by V of discrete levels, namely, the likely outcome of each sample for the V level of a discrete one, The biggest channel data rate Rm ax as follows:Rmax = 2Blog 2 V (bit / s)For example, a 3000 Hz noise bandwidth of the channel should not transmit rate of more than 6,000 bits / second binary digital signal.In front of us considered only the ideal noise-free channel. There is noise in the channel, the situation will rapidly deteriorate. Channel Thermal noise with signal power and noise power ratio to measure the signal power and noise power as the signal-to-noise ratio (S ignal - to -- Noise Ratio). If we express the signal power S, and N express the noise power, while signal to noise ratio should be expressed as S / N. However, people Usually do not use the absolute value of signal to noise ratio, but the use of 10 lo g1 0S / N to indicate the units are decibels (d B). For the S / N equal 10 Channel, said its signal to noise ratio for the 1 0 d B; the same token, if the channel S / N equal to one hundred, then the signal to noiseratio for the 2 0 d B; And so on. S hannon noise channel has about the maximum data rate of the conclusions are: The bandwidth for the BH z, signal to noise ratio for the S / N Channel, the maximum data rate Rm ax as follows:Rmax = Blog 2 (1 + S / N) (bits / second)For example, for a bandwidth of 3 kHz, signal to noise ratio of 30 dB for the channel, regardless of their use to quantify the number of levels, nor Fast sampling rate control, the data transfer rate can not be greater than 30,000 bits / second. S h a n n o n the conclusions are derived based on information theory Out for a very wide scope, in order to go beyond this conclusion, like you want to invent perpetual motion machine, as it is almost impossible.It is worth noting that, S hannon conclusions give only a theoretical limit, and in fact, we should be pretty near the limit Difficult.SUMMARYMessage signals are (or data) of a magnetic encoder, the signal contains the message to be transmitted. Signal according to the dependent variable Whether or not a row of values, can be classified into analog signals and digital signals, the corresponding communication can be divided into analog communication and digital communication.Fourier has proven: any signal (either analog or digital signal) are different types of harmonic frequencies Composed of any signal has a corresponding bandwidth. And any transmission channel signal attenuation signals will, therefore, Channel transmission of any signal at all, there is a data transfer rate limitations, and this is Chengkui N yquist (Nyquist) theorem and S hannon (Shannon) theorem tells us to conclusions.Transmission medium of computer networks and communication are the most basic part of it at the cost of the entire computer network in a very Large proportion. In order to improve the utilization of transmission medium, we can use multiplexing. Frequency division multiplexing technology has many Road multiplexing, wave division multiplexing and TDM three that they use on different occasions.Data exchange technologies such as circuit switching, packet switching and packetswitching three have their respective advantages and disadvantages. M odem are at Analog phone line for the computer's binary data transmission equipment. Modem AM modulation methods have, FM, phase modulation and quadrature amplitude modulation, and M odem also supports data compression and error control. The concept of data communications Data communication is based on "data" for business communications systems, data are pre-agreed with a good meaning of numbers, letters or symbols and their combinations.参考文献[1]C.Y.Huang and A.Polydoros,“Two small SNR classification rules for CPM,”inProc.IEEE Milcom,vol.3,San Diego,CA,USA,Oct.1992,pp.1236–1240.[2]“Envelope-based classification schemes for continuous-phase binary Frequency-shift-keyed modulations,”in Pr oc.IEEE Milcom,vol.3,Fort Monmouth,NJ,USA,Oct.1994,pp. 796–800.[3]A.E.El-Mahdy and N.M.Namazi,“Classification of multiple M-ary frequency-shift keying over a rayleigh fading channel,”IEEE m.,vol.50,no.6,pp.967–974,June 2002.[4]Consulative Committee for Space Data Systems(CCSDS),Radio Frequency and Modulation SDS,2001,no.401.[5]E.E.Azzouz and A.K.Nandi,“Procedure for automatic recognition of analogue and digital modulations,”IEE mun,vol.143,no.5,pp.259–266,Oct.1996.[6]A.Puengn im,T.Robert,N.Thomas,and J.Vidal,“Hidden Markov models for digital modulation classification in unknown ISI channels,”in Eusipco2007,Poznan,Poland, September 2007,pp.1882–1885.[7]E.Vassalo and M.Visintin,“Carrier phase synchronization for GMSK signals,”I nt.J.Satell. Commun.,vol.20,no.6,pp.391–415,Nov.2002.[8]J.G.Proakis,Digital Communications.Mc Graw Hill,2001.[9]L.Rabiner,“A tutorial on hidden Markov models and selected applications in speechrecognition,”Proc.IEEE,vol.77,no.2,pp.257–286,1989.英文译文：数据通信Gildas Avoine and Philippe OechslinEPFL, Lausanne, Switzerlandfgildas.avoine, philippe.oechsling@ep.ch摘要数据通信是通信技术和计算机技术相结合而产生的一种新的通信方式。
通信外文翻译外文文献英文文献及译文
通信外文翻译外文文献英文文献及译文Communication SystemA generalized communication system has the following components:(a) Information Source. This produces a message which may be written or spoken words, or some form of data.(b) Transmitter. The transmitter converts the message into a signal, the form of which is suitable for transmission over the communication channel.(c) Communication Channel. The communication channel is the medium used transmit the signal, from the transmitter to the receiver. The channel may be a radio link or a direct wire connection.(d) Receiver. The receiver can be thought of as the inverse of the transmitter. Itchanges the received signal back into a message and passes the message on to its destination which may be a loudspeaker，teleprinter or computer data bank.An unfortunate characteristic of all communication channels is that noise is added to the signal. This unwanted noise may cause distorionsof sound in a telephone, or errors in a telegraph message or data.Frequency Diversion MultiplexingFrequency Diversion Multiplexing(FDM) is a one of analog technologies. A speech signal is 0~3 kHz, single sideband amplitude (SSB) modulation can be used to transfer speech signal to new frequency bands,four similar signals, for example, moved by SSB modulation to share the band from 5 to 20 kHz. The gaps between channels are known as guard spaces and these allow for errors in frequency, inadequate filtering, etc in the engineered system.Once this new baseband signal, a "group" of 4 chEmnels, has been foimed it ismoved around the Lrunk network as a single unit. A hierarchy can be set up withseveral channels fonning a "group". several groups a "supergroup" and several"supergraup" eicher a "nmsrergroup" or "hypergroup".Groups or supergroups are moved around as single units by the communicationsequipment and it is not necessary for the radios to know how many channels are involved. A radio can handle a supergroup provided sufficient bandwidth is available. The size of the groups is a compromise as treating each channel individually involves far more equipment because separate filters, modulators and oscillators are required for every channel rather than for each group. However the failure of one module will lose all of the channels associated with a group.Time Diversion MultiplexingIt is possible, with pulse modulation systems, to use the between samples to transmit signals from other circuits. The technique is knownas time diversion multiplexing (TDM). To do this, it is necessary to employ synchronized switches at eachend of the communication links to enable samples to be transmittedin turn, from each of several circuits. Thus several subscribers appear to use the link simultaneously. Although each user only has periodic short time slots, the original analog signalsbetween samples can be reconstituted at the receiver.Pulse Code ModulationIn analog modulation, the signal was used to modulate the amplitude or frequency of a carrier, directly. However, in digital modulation a stream of pulse, representing the original，is created. This stream is then used to modulate a carrier or alternatively is transmitted directly over a cable. Pulse Code Modulation (PCM) is one of the two techniques commonly used.All pulse systems depend on the analog waveform being sampled at regular intervals. The signal created by sampling our analog speech input is known as pulse amplitude modulation. It is not very useful in practice but is used as an intermediate stage towards forming a PCM signal. It will be seen later that most of the advantages of digital modulation come from the transmitted pulses having two levels only, this being known as a binary system. In PCM the height of each sample is converted into a binary number. There are three step in the process of PCM: sampling, quantizing and coding.Optical Fiber CommunicationsCommunication may be broadly defined as the transfer of information from one point to another. When the information is to be conveyed over any distance acommunication system is usually required. Within a communication system the information transfer is frequently achieved by superimposing or modulating the information on to an electromagnetic wave which acts as a carrier for the informationsignal. This modulated carrier is then transmitted to the required destination where it is received and the original information signal is obtained by demodulation. Sophisticated techniques have been developed for this process by using electromagnetic carrier wavesoperating at radio frequencies as well as microwave and millimeter wave frequencies. However，拻 communication?may also be achieved by using an electromagneticcarrier which is selected from the optical range of frequencies.In this case the information source provides an electrical signal to a transmitter comprising an electrical stage which drives an optical source to give modulation of the light-wave carrier. The optical source which provides the electrical-optical conversionmay be either a semiconductor laser or light emitting diode (LED). The transmission medium consists of an optical fiber cable and the receiver consists of an optical detector which drives a further electrical stage and hence provides demodulation optical carrier. Photodiodes (P-N, P-I-N or avalanche) and , in some instances,phototransistor and photoconductors are utilized for the detection of the optical signal and the electrical-optical conversion. Thus there is a requirement for electrical interfacing at either end of the optical link and at present the signal processing is usually performed electrically.The optical carrier may be modulated by using either an analog or digital information signal. Analog modulation involves the variation of the light emitted from the optical source in a continuous manner. With digital modulation, however, discrete changes in the light intensity are obtained (i.e. on-off pulses). Although often simpler to implement, analog modulation with an optical fiber communication system is lessefficient, requiring a far higher signal to noise ratio at the receiver than digital modulation. Also, the linearity needed for analog modulation is not always provided by semiconductor optical source, especially at high modulation frequencies. For thesereasons，analog optical fiber communications link are generally limited to shorter distances and lower bandwidths than digital links.Initially, the input digital signal from the information source is suitably encoded for optical transmission. The laser drive circuit directly modulates the intensity of the semiconductor laser with the encoded digital signal. Hence a digital optical signal is launched into the optical fiber cable. The avalanche photodiode detector (APD) is followed by a fronted-end amplifier and equalizer orfilter to provide gain as well as linear signal processing and noise bandwidth reduction. Finally, the signal obtained isdecoded to give the original digital information.Mobile CommunicationCordless Telephone SystemsCordless telephone system are full duplex communication systems that use radio to connect a portable handset to a dedicated base station，which is then connected to adedicated telephone line with a specific telephone number on the public switched telephone network (PSTN) .In first generation cordless telephone systems5(manufactured in the 1980s), the portable unit communications only to the dedicatedbase unit and only over distances of a few tens of meters.Early cordless telephones operate solely as extension telephones to a transceiver connected to a subscriber line on the PSTN and are primarily for in-home use.Second generation cordless telephones have recently been introduced which allowsubscribers to use their handsets at many outdoor locations within urban centers such as London or Hong Kong. Modern cordless telephones are sometimes combined with paging receivers so that a subscriber may first be paged and then respond to the pageusing the cordless telephone. Cordless telephone systems provide the user with limited range and mobility, as it is usually not possible to maintain a call if the user travels outside the range of the base station. Typical second generation base stations provide coverage ranges up to a few hundred meters.Cellular Telephone SystemA cellular telephone system provides a wireless connection to the PSTN for any user location within the radio range of the system.Cellular systems accommodate alarge number of users over a large geographic area, within a limited frequency spectrum. Cellular radio systems provide high quality service that is often comparable to that of the landline telephone systems. High capacity is achieved by limiting the coverage of each base station transmitter to a small geographic area called a cell so that the same radio channels may be reused by another base station located some distance away. A sophisticated switching technique called a handoff enables a call to proceeduninterrupted when the user moves from one cell to another.A basic cellular system consists of mobile station, base stations and a mobile switching center (MSC). The Mobile Switching Center is sometimes called a mobiletelephone switching office (MTSO), since it is responsible for connecting all mobiles to the PSTN in a cellular system. Each mobilecommunicates via radio with one of the base stations and may be handed-off to any number of base stations throughout the duration of a call. The mobile station contains a transceiver, an antenna, and control circuitry，and may be mounted in a vehicle or used as a portable hand-held unit. Thebase stations consists of several transmitters and receivers which simultaneously handlefull duplex communications and generally have towers which support several transmitting and receiving antennas. The base station serves as a bridge between all mobile users in the cell and connects the simultaneous mobile calls via telephone linesor microwave links to the MSC. The MSC coordinates the activities of all the base stations and connects the entire cellular system to the PSTN. A typical MSC handles 100000 cellular subscribers and 5000 simultaneous conversations at a time, andaccommodates all billing and system maintenance functions, as well. In large cities, several MSCs are used by a single carrier.Broadband CommunicationAs can be inferred from the examples of video phone and HDTV, the evolution offuture communications will be via broadband communication centered around video signals. The associated services make up a diverse set of high-speed and broadbandservices ranging from video services such as video phone，video conferencing，videosurveillance, cable television (CATV) distribution, and HDTV distribution to the high-speed data services such as high-resolution image transmission, high-speed datatransmission, and color facsimile. The means of standardizing these various broadbandcommunication services so that they can be provided in an integrated manner is no other than the broadband integrated services digital network (B-ISDN). Simple put, therefore,the future communications network can be said to be a broadband telecommunicationsystem based on the B-ISDN.For realization of the B-ISDN, the role of several broadband communicationtechnologies is crucial. Fortunately, the remarkable advances in the field of electronics and fiber optics have led to the maturation of broadband communication technologies.As the B-ISDN becomes possible on the optical communication foundation, the relevant manufacturing technologies for light-source and passive devices and for optical fiberhave advanced to considerable levels. Advances in high-speed device and integratedcircuit technologies for broadband signal processing are also worthy of close attention. There has also been notable progress in software, signal processing, and video equipment technologies. Hence, from the technological standpoint, the B-ISDN hasfinally reached a realizable state.On the other, standardization activities associated with broadband communication have been progressing. The Synchronous Optical Network (SONET) standardization centered around the T1 committee eventually bore fmit in the form of the Synchronous Digital Hierarchy (SDH) standards of the International Consultative Committee in Telegraphy and Telephony (CCITT), paving the way for synchronous digital transmission based on optical communication. The standardization activities of the 5integrated services digital network (ISDN), which commenced in early 1980s with the objective of integrating narrowband services, expanded in scope with the inclusion of broadband services, leading to the standardization of the B-ISDN in late1980抯 and establishing the concept of asynchronous transfer mode (ATM)communication in process. In addition, standardization of various video signals is becoming finalized through the cooperation among such organizations as CCITT, the International Radio-communications Consultative Committee (CCIR), and theInternational Standards Organization (ISO), and reference protocols for high-speedpacket communication are being standardized through ISO, CCITT, and the Institute of Electrical and Electronics Engineer (IEEE).Various factors such as these have made broadband communication realizable.5Therefore, the 1990s is the decade in which matured broadband communicationtechnologies will be used in conjunction with broadband standards to realize broadband communication networks. In the broadband communication network, the fiber opticnetwork will represent the physical medium for implementing broadband communication, while synchronous transmission will make possible the transmission of broadband service signals over the optical medium. Also, the B-ISDN will be essentialas the broadband telecommunication network established on the basis of optical medium and synchronous transmission and ATM is the communication means that enables the realization of the B-ISDN. The most important of the broadband services to be providedthrough the B-ISDN are high-speed data communication services and videocommunication services.Image AcquisitionA TV camera is usually used to take instantaneous images and transform them into electrical signals, which will be further translated into binary numbers for the computer to handle. The TV camera scans oneline at a time. Each line is further divided into hundreds of pixels. The whole frame is divided into hundreds (for example, 625) of lines.The brightness of a pixel can be represented by a binary number with certain bits, for example, 8 bits. The value of the binary number varies from 0 to 255, a range great enough to accommodate all possible contrast levels of images taken from real scene.These binary numbers are sorted in an RAM (it must have a great capacity) ready for processing by the computer.Image ProcessingImage processing is for improving the quality of the images obtained. First, it is necessary to improve the signal-to-noise ratio. Here noise refers to any interference flaw or aberation that obscure the objects on the image. Second, it is possible to improve contrast, enhance sharpness of edges between images through various computational means.Image AnalysisIt is for outlining all possible objects that are included in the scene. A computer program checks through the binary visual informationin store for it and identifies specific feature and characteristics of those objects. Edges or boundaries are identifiablebecause of the different brightness levels on either side of them. Usingcertain algorithms, the computer program can outline all possible boundaries of the objects in the scene. Image analysis also looks for textures and shadings between lines.Image ComprehensionImage Comprehension means understanding what is in a scene. Matching the prestored binary visual information with certain templates which represent specific objects in a binary form is technique borrowed from artificial intelligence, commonly referred to as "templeite matching"emplate matching? One by one,the templates are checked against the binary information representing the scene. Once a match occurs, an object is identified. The template matching process continues until all possible objects in the scene have been identified, otherwise it fails.通信系统一般的通信系统由下列部分组成:信源。
无线通信外文翻译
无线通信外文翻译南京工程学院毕业设计文献资料翻译,原文及译文,原文名称: Wireless Communications课题名称: 无线电子门铃设计学生姓名: 顾玲玲学号: 208080603 指导老师: 马新华所在系部: 通信工程学院专业名称: 电子信息工程2012 年 3 月南京Wireless CommunicationsModern computer technology, industrial revolution, the world economy from the capital into the economy to knowledge economy. Field in the electronic world, fromthstthe 20 century into the era of radio to computer technology in the 21 century as thecenter of the intelligent modern era of electronic systems. Thebasic core of modern electronic systems are embedded computer systems (referred to as embedded systems), while the microcontroller is the most typical and most extensive and most popular embedded systems.Fist, radio has created generations of excellence in the world.thFifties and sixties in the 20 century, the most representative of the advancedelectronic, technology is wireless technology, including radio broadcasting, radio, wireless communications (telegraph) ,Amateur Radio,radio positioning, navigation and other telemetry, remote control, remote technology. Early that these electronic technology led many young people into the wonderful digital world, radio show was a wonderful life, the prospects for science and technology. Electronics began to form a new discipline. Radio electronics, wireless communications began e-world journey. Radio technology not only as a representative of advanced science and technology at that time, but also from popular to professional fields of science, attracting the young people and enable them to find a lot of fun. Ore from the bedside to the superheterodyne radio; report issued from the radio amateur radio stations; from the telephone, electric bell to the radio control model. Became popularyouth radio technology, science and technology education is most popular and most extensive content. So far, many of the older generation of engineer, experts. Professor of the year are radio enthusiasts. Funradio technology, radio technology, components to the radio-based remote control, telemetry, remote electronic systems, has trained several generations of technological excellence.Second, from the popularity of the radio era to era of electronic technology. The early radio technology to promote the development of electronic technology, most notably electronic vacuum tube technology to semiconductor electronic technology, Semiconductor technology to realize the active device miniaturization and low cost, so more popular with radio technology and innovation, and to greatly broaden the number ofnon-radio-control areas. The development of semiconductor technologyleads to the production of integrated circuits. Electronic design engineers1no longer use the discrete electronics components designed circuit modules, and direct selection of integrated circuit componentsconstitute a single system. They freed the design of the circuit unit dedicated to system design, greatly liberating the productive forces of science and technology; promote the wider spread of electronic systems. Semiconductor integrated circuits in the basic digital logic circuits first breakthrough. A large number of digital logic circuits, such as gates, counters, timers, shift registers, and analog switches, comparators, etc., for the electronic digital control provides excellent conditions for the traditional mechanical control to electronic control. Power electronic devices and sensor technology to make the original to the radio as the center of electronic technology turned to mechanical engineering in the field of digital control systems, testing in thefield of information collection, movement of electrical mechanical servo drive control object. Semiconductor and integrated circuit thunit-specific electronic technology a part of. 70 years into the20 century, large scaleintegrated circuit appeared to promote the conventional electronic circuit unit-specific electronic systems development. Many electronic systems unit into a dedicated integrated device such as radios, electronic clocks, calculators, electronic engineers in these areas fromthe circuit, the system designed to debug into the device selection, peripheral device adapter work. Electronic technology, and electronic products enriched, electronic engineers to reduce the difficulty, but at the same time, radio technology, electronic technology has weakened the charm. The development of semiconductor integrated circuits classical electronic systems are maturing, remain in the large scale integrated circuit other than the shrinking of electronic technology, electronic technology is not the old days of radio fun times and comprehensive engineering training.Third, from the classic era of electronic technology to modern electronic technology of the times.th80 years into the 20 century of economic change is most important revolution inthe computer. The computer revolution in the most important sign is the birth of the computer embedded applications. Modern computer numerical requirements should be born. A long period of time is to develop the massive computer numerical duty. But the computer shows the logic operation, processing, control, attracting experts in the filed of electronic control, they want development to meet the control, object requirements of embedded applications computer systems. If you meet the massive data-processing computer system known as general-purpose computer system, then2the system can be the embedded object(such as ships, aircraft, motorcycles, etc.) in a computer system called the embedded computer. Clearly, both the direction of technology development is different. The former requires massive data storage, handling, processing and analysis of high-speed data transmission; while the latter requires reliable operation in the target environment, the external physical parameters on high-speed acquisition, analysis and processing logic and the rapid control of external objects. It will add an early general-purpose computer data acquisition unit, the output driver circuit reluctance to form a heat treatment furnace temperature control system. This general-purpose computer system is not possible for most of the electronic system used, and to make general-purpose computer system meets the requirements of embedded applications, will inevitably affect the development of high-speed numeric processing. In order to solve the contradiction between thethdevelopment of computer of computer technology, in the 20 century 70s.,semiconductor experts another way, in full accordance with the electronic system embedded computer application requirements, a micro-computer’s basic system on achip, the formation of early SCM(single Chip Microcomputer). After the advent of single chip in the computer industry began to appear in the general-purpose computer systems and embedded systems the two branches. Since then, both the embedded system, and general-purposecomputer systems have been developed rapidly. Although the early general-purpose computer converted the embedded system began in the emergence of SCM. Because the microcontroller is designed specifically for embedded applications, the MCU can only achieve embedded applications. MCU embedded applications that best meet environmental requirements, for example, chip-level physical space, large-scale instruction. A computer system microcontroller core embedded electronic systems, intelligent electronic systems for the foundation. Therefore, the current single chip electronic system in widespread use of electronic systems to enable rapid transition to the classical modern intelligent electronic systems.译文无线通信从无线电世界到单片机世界，现代计算机技术的产业革命将世界经济从资本经济带入到知识经济时代。
通信工程外文文献翻译
毕业设计（论文）的外文文献翻译原始资料的题目/来源：Fundamentals of wireless communications by David Tse翻译后的中文题目：无线通信基础专业通信工程学生王晓宇学号110240318班号1102403指导教师杨洪娟翻译日期2015年6月15日外文文献的中文翻译7．mimo：空间多路复用与信道建模本书我们已经看到多天线在无线通信中的几种不同应用。
在第3章中，多天线用于提供分集增益，增益无线链路的可靠性，并同时研究了接受分解和发射分解，而且，接受天线还能提供功率增益。
在第5章中，我们看到了如果发射机已知信道，那么多采用多幅发射天线通过发射波束成形还可以提供功率增益。
在第6章中，多副发射天线用于生产信道波动，满足机会通信技术的需要，改方案可以解释为机会波束成形，同时也能够提供功率增益。
章以及接下来的几章将研究一种利用多天线的新方法。
我们将会看到在合适的信道衰落条件下，同时采用多幅发射天线和多幅接收天线可以提供用于通信的额外的空间维数并产生自由度增益，利用这些额外的自由度可以将若干数据流在空间上多路复用至MIMO信道中，从而带来容量的增加：采用n副发射天线和接受天线的这类MIMO 信道的容量正比于n。
过去一度认为在基站采用多幅天线的多址接入系统允许若干个用户同时与基站通信，多幅天线可以实现不同用户信号的空间隔离。
20世纪90年代中期，研究人员发现采用多幅发射天线和接收天线的点对点信道也会出现类似的效应，即使当发射天线相距不远时也是如此。
只要散射环境足够丰富，使得接受天线能够将来自不同发射天线的信号分离开，该结论就成立。
我们已经了解到了机会通信技术如何利用信道衰落，本章还会看到信道衰落对通信有益的另一例子。
将机会通信与MIMO技术提供的性能增益的本质进行比较和对比是非常的有远见的。
机会通信技术主要提供功率增益，改功率增益在功率受限系统的低信噪比情况下相当明显，但在宽带受限系统的高信噪比情况下则很不明显。
通信工程 毕业设计 外文文献翻译：超宽带系统的数据通信
英文资料Ultra-Wideband Systems for Data CommunicationsG. Racherla, J.L. Ellis, D.S. Furuno, S.C. LinGeneral Atomics, Advanced Wireless Group10240 Flanders Ct. San Diego CA 92121WebsitABSTRACTUltra-Widebandt (UWB) is a radio transmission scheme that uses extremely low power pulses of radio energy spread across a wide spectrum of frequencies. UWB has several advantages over conventional continuous wave radio communications including potential support for high data rates, robustness to multipath interference and fading. We present an overview of UWB technology and its use in data communications and networking. We look at design considerations for UWB based networks at various layers of the protocol stack.1.INTRODUCTIONUltra-Wideband [1-6]一also known as baseband or impulse radio一is a carrier-free radio transmission that uses narrow, extremely low power pulses of radio energy spread across a wide spectrum of frequencies. UWB has recently gained a great deal of interest due to the recent Federal Communications Commission (FCC) Report and Order which allocates the UWB band一7.5 GHz of unlicensed spectrum for indoor and outdoor communication applications. UWB communications are required to have a -10 dB fractional bandwidth of more than 20% or a -10 dB bandwidth of more than 500 MHz [7]. It is important to note that the FCC has not defined a specific modulation scheme to be used. UWB systems offer the promise of high data rate, low susceptibilityto multipath fading, high transmission security low prime power requirements, low cost, and simple design [1,2,5,6].UWB has been used in military applications for the past several years for ground-penetrating precision radar applications and secure communications [3,8]. For the past few years, UWB has been developed for commercial applications [1,2,5,6]. With the recent FCC [7] report and order for theuse of UWB technology, there has been an added impetus to this endeavor. Other notable UWB applications include collision avoidance radar, tagging/identification; geolocation [9] and data communications in personal area networks (PAN) and local area network (LAN) environments.There are several future challenges to the wide adoption of UWB for wireless data communications including the infancy of the technology in the commercial arena, lack of reliablechannel models, the early stages of standardization effort and lack of low-cost system on chip (SoC) implementations. In this paper, we look at UWB technology for data communications and inside a UWB physical (PHY) layer characteristics. We also briefly introduce other related wireless standards such as 802.11 [10], 802.15.3 [11-13] Bluetooth [14], HomeRF [15] and HIPERLAN [16] and present a brief synopsis of the regulatory effort worldwide with special emphasis on the FCC. We also present the design considerations for UWB based data networking.2.ULTRA-WIDEBAND TECHNOLOGYThe basic waveform that employed in a UWB system is an approximation to an impulse, such as that shown in Fig. 1. The short duration of the pulse is associated with large inherent bandwidth; hence, the nomenclature "Ultra-Wideband". Typical attributes of UWB waveforms are summarized in Table 1.Fig. 1. UWB waveform example.The high spectral content of the UWB waveform gives rise to one of the primary advantages UWB operation for communications where a UWB system is robust against multipath fading[17] and narrowband interference [18]. In multipath fading, where the transmitted radio frequency (rt) signal can reflect off objects in its transmission path and can cause destructive interferences at the receiver, a loss of reception can occur. ThisTable 1: Characteristics of Typical UWB SystemsFractional Bandwidth > 20%Pulse Width 0.1-2 asPulse Repetition Frequency 1 kHz-2 GHzAverage Transmitted Power<1mWeffect is particularly problematic indoors where there are many reflecting surfaces. In the frequency domain, multipath is shown as frequency selective fading. Because UWB communications systems spreads the transmitted data over a broad frequency band if destructive interference occurs at a specific frequency, whether due to multipath or narrowband interference, the information can still be recovered over the good frequencies.UWB implementations can provide low complexity, low cost solutions [19], thus enabling vast deployments of the technology. A critical component that reaffirms a low cost solution is noting that UWB signals, being carrier-less, have greater simplicity over narrowband transceivers and require smaller silicon die sizes [20]. UWB can be designed to achieve very high bit rates while still achieving low power consumption, a feature set which will be exploited by the consumer electronics industry [21]. UWB schemes can further be designed to be very scalable in terms of complexity, bit rate, power consumption, and range.UWB technology can support many applications. Different UWB modulation schemes offer different advantages for communication, radar, and precisiongeo-location applications. UWB technology, which operates between 3.1 and 10.6 GHz, intrinsically offers an efficient reuse of precious spectrum by operating stealthily at the noise floor [22]. This UWB system operates at low power, to be compliant with operating under FCC Part 15 emissions, across a wide range of frequencies. As a spread spectrum technology, UWB offers a low probability of intercept and a low probability of detection [8]. Thus, it is particularly well suited for covert military or sensitive usage seenarios [8]. Because UWB signals have extremely short bursts in time (e.g., durations of 1 ns or less) they are suited for precision geo-location applications. Though UWB intrinsically offers the above-mentioned features, application optimization and improvements on these characteristics are left to specific designs and implementations, most notably by careful consideration of modulation schemes.2.1. UWB System Design ConsiderationsSeveral considerations are needed when designing a PAN. First, low power design is necessary because the portable devices within the network are battery powered. Second, high data rate transmission is crucial for broadcasting multiple digi\tal audio and video streams: Lastly, low cost is a prerequisite to broadening consumer adoption. In addition to these criteria, the UWB system designer must address synchronization and coexistence. Capturing and locking onto these short pulses make synchronization a non-trivial task. Coexisting peacefully with other wireless systems without interference is important;In particular, one needs to pay attention to the 802.1 la wireless LANs that operate in the 5 GHz ISM bands.At the physical layer, additional challenges lie in the transceiver and antenna design. At the transmitter, pulse shaping is required to produce flat and wideband emission in the desired frequency bands. Although new integrated circuits provide less expensive forms of integration, the pulses can be affected by the parasitics from the component and packaging [23]. To accommodate the high data rates, tradeoffs between high and low pulse repetition frequency (PRF) and modulation schemes must be considered. The low PRF system with higher modulation (more bits per symbol) may require a more complex receiver, while the high PRF system with lower modulation may lead to performance degradation for delay spread in the channel. Finally, traditional antenna designs gear towards narrow band systems. To avoid dispersion at the receiver, the new wideband antennas need phase linearity and a fixed phase center [23].3. UWB STANDARDIZATION ANDREGULATORY EFFORTSThere are several standards bodies presently considering, at some level, UWB technologies. The standards body most advanced in the consideration of UWB is study group "a" of IEEE 802.15.3, which was formed in November 2001 [11-13]. A serious effort is well underway to define a UWB channel model, and numerous UWB tutorials have been given. Many hallway conversations talk to a physical layer standard being ratified in 2004 (though there is no formal knowledge or position on this) and will accompany the soon to be approved 802.15.3 Medium Access Control (MAC) which supports quality of service (QoS) for real-time multimedia applications [12]. The technical requirements presently call for bit rates of 110 to 200 Mbps at ranges up to 10 m, with the option to achieve 480 Mbps possibly at shorter distances. The powerconsumption requirement is presently set at 100 to 250 mW with lOe 5 bit error rate at the top of the physical layer. Complexity/cost are presently expected to be comparable to Bluetooth and the physical layer is required to support four collocated piconets. Coexistence is presently crucial (e.g., IEEE 802.1 la) and the ability to scale the technology is key to a long lasting and widely adopted standard. These technical requirements come from documents that are still being revised; additionally, it is not possible to predict if proposals may fall short of meeting some of the desired requirements.The United States FCC issued a report and order in the early part of 2002. This landmark decision to permit UWB operation in the 3.1 to 10.6 GHz spectrum under Part 15 emis- sion limits, with some additional restrictions, has catalyzed development and standardization processes as is evident by the sheer number of entities (companies, academic and government institutions) associated with UWB and through the serious efforts of the IEEE 802.15.3 group. The FCC carefully chose the frequency band of operation to be above 3.1 GHz to avoid interfering with GPS and other life critical systems. Furthermore, the FCC ruled that emissions below Part 15 would pro-vide for peaceful coexistence, the ability to have narrowband and UWB systems collocated on a non-interfering basis, because unintentional emissions from devicessuch as laptops are also limited to Part 15 rules. This ruling makes it possible to have up to 15 UWB frequency bands in the 7.5 GHz allocated unlicensed spectrum [7]. Extensive efforts are being conducted throughout Europe (CEPT, ETSI, and the European Commission), Korea, and Japan (Association of Radio Industries and Businesses, and the Japanese Ministry of Telecommunications).4. NETWORKING WITH UWB SYSTEMSThere is a significant interest in the ability to perform location determination and tracking of assets and people throughout warehouses, factories, ships, hospita梦，business environments, and other buildings or structures. The ability for UWB technologies to operate within such intense multipath environments in conjunction with the ability for UWB to provide very accurate geo-location capability at low cost and long battery life justifies the increasing technological activity in this market [20].As the rf tags [24] are distributed, it is also recognized tha they can be coordinated and networked. To further reduce the cost of the transceivers, position determination can occur at networked computer terminals. Additionally, it is quite conceivable that tag complexity can be further simplified by installink transmitters that chirp periodically [8]. Just as UWB demonstrates many benefits for rf tags, the technology equally lends itself to distributed sensor networks [9]. Sensor network applications include feedback controls systems and environmental surveillance for commercial, industrial,_ and military applications.In the data communication area, UWB technology may be used to implement ad-hoc networks. An ad-hoc network [25-27] is characterized by a collection of hosts that form a network "on-the-fly". An ad-hoc network is a multi-hop wireless network wherein each host also acts as a router. Mobile TRANSPORT Ad-hoc NETworks (MANETs) [25-27] are ad-hoc networks wherein the wireless hosts have the ability to move. Mobility of hosts in MANETs has a profound impact on the topology of the network and its performance. Figure 2 illustrates how the various layers of the OSI protocol stack have to operate in order to successfully complete a communication session. We look at some of relevant design issues at the different layers for UWB-based sensor networks and MANETs.4.1. Design Issues for Layers of the Protocol StackThere are several design considerations of sensor networks setup (including rftags) [24]. The sensors typically work on batteries and need be low cost, low power, with LPI/LPD and the ability to do geo-location. All of these requirements are satisfied by a UWB PHY.The PHY layer [26,27] is a very complex layer which deals with the medium specification (physical, electrical and mechanical) for data transmission between devices. The PHY layer specifies the operating frequency range, the operating temperature range, modulation scheme, channelization scheme. channel switch time, timing, synchronization, symbol coding, and interference from other systems, carrier-sensing and transmit/receive operations of symbols and power requirements for operations. The PHY layer interacts closely with, the MAC sublayer to ensure smooth performance of the network. The PHY layer for wireless systems (such as MANETs) has special considerations to take into account as the wireless medium is inherently error-prone and prone to interference from other wireless and rf systems in the proximity. Multipath is important to consider when designing wireless PHY layer as the rf propagation environment changes dynamically with time; frequent disconnections may occur. The problem is exacerbated when the devices in the network are mobile because of handoffs and new route establishment. It should be noted that there is a concerted effort by several UWB companies muster supportfor a UWB-based high data rate PITY in the IEEE 802.15.3 working group.The data link layer consists of the Logical Link Control (LLC) and the MAC sub layers. The MAC sublayer is responsible for channel access and the LLC is responsible for link maintenance, framing data unit, synchronization, error detection and possible recovery, and flow control. The MAC sublayer tries to gain access to the shared channel to prevent collision and distortion of transmitted frames with frames sent by the MAC sublayers of other nodes sharing the medium. TheMAC sublayer in sensor networks and MANETs needs to be power-aware, self-organizing and support mobility and handoffs.The network layer of such networks should perform routing so as to minimize power and the number of node hops in the route. In some cases, flooding/gossiping may be required to increase chances of the packets reaching the destination. Data aggregation/fusion may be used for. data-centric routing [24] in the network layer. The network layer needs to allow for route maintenance and updates for fast changing network topology.The transport layer is responsible for the end-to-end integrity of data in thenetwork. The transport layer performs multiplexing, segmenting, blocking, concatenating, error detection and recovery, flow control and expedited data transfer. In the MANET environment, the mobility of the nodes will almost certainly cause packets to be delivered out of order and a significant delay in the acknowledgements is to be expected as a result. Retransmissions are very expensive in terms of the power requirements. Transport protocols for MANETs and sensor networks need to focus on the development of feedback mechanisms that enable the transport layer to recognize the dynamics of the network and adjust its retransmission timer, window size and perform congestion control with more information on the network.Fig. 2. Issues at each layer of the protocol stackThe application layer needs support for location-based services, network management, task assignment, query and data dissemination for sensor networks and possible MANETs.5. RELATED TECHNOLOGIESIn order to better understand UWB-based technologies, we look at some related technology standards. More information on these technologies can be found in Ref. 27.5.1. BluetoothBluetooth [14] is a short-range radio technology standard originallyintended as a wireless cable replacement to connect portable computers, wireless devices, handsets and headsets. Bluetooth devices operate in the 2.4 GHz ISM band. Bluetooth uses the concept of a piconet which is a MANET with a master device controlling one or several slave devices. Bluetooth also allow scatternets wherein a slave device can be part of multiple piconets. Bluetooth has beed designed to handle both voice and data. traffic.5.2. HIPERIANl1 and HIPERIANIlHIPERLAN/I and HIPERLAN/2 [16] are European wireless LAN (WLAN) standards developed by European Telecommunications Standards Institute (ETSI). HIPERLAN/1 is a wireless equivalent of Ethernet while HIPERLAN/2 has architecture based on wireless Asynchronous Transfer Mode (ATM). Both the standards use dedicated frequency spectrum at -5 GHz. HIPERLAN/I provides a gross data rate of 23.5 Mb/s and net data rate of more than 18 Mb/s while HIPERLAN/2 provides gross data rates of 6/16/36154 Mb/s and a maximum of 50 Mb/s net data rate. Both standards use 10/100/1000 mW of transmit power and have a maximum range of 50 m. Also, the standards provide isochronous and asynchronous services with support for QoS. However, they have different channel a-ss and modulation schemes.5.3. IEEE 802]]This IEEE family of wireless Etherdet standards is primarily intended for indoor and in-building WLANs. There are several varities of this standard. The current available versions are the 802.1 la, 802.11b and 802.llg (emerging draft standard) with other versions which are starting to show on the horizon [10]. The 802.11 standards support ad-hoc networking as well as connections using an access point (AP). The standard provides specifications of the PHY and the MAC layers. The MAC specified uses CSMA/CA for access and provides service discovery and scanning, link setup and tear down, data fragmentation, security, power management and roaming facilities. The 802.1 la PHY is similar to the HIPERLAN/2 PHY. The PHY uses OFDM and operates in the 5 GHz UNII band. 802.1 la supports data rates ranging from 6 to 54 Mbps. 802.11 a currently offers much less potential for rf interference than other PHYs (e.g., 802.11b and 802.11g) that utilize the crowded 2.4 GHz ISM band. 802.11 a can support multimedia applications in densely populated user environments.' The 802.11b standard, proposed jointly by Harris and Lucent Technologies, extends the 802.11 Direct Sequence Spread Spectrum (DSSS) PHY to provide 5.5 and 11 Mb/s data rates.5.4. IEEE 802.75.3The emerging draft standard [11-13] defines MAC and PHY (2.4 GHz) layer specifications for a Wireless Personal Area Network (WPAN). The standard is based on the concept of a piconet which is a network confined to a 10 m personal operating space (POS) around a person or object. A WPAN consists of one or more collocated piconets. Each piconet is controlled by a piconet coordinator (PNC) and may consist of devices (DEVs). The 802.15.3 PHY is defined for 2.4 to 2.4835 GHz band and has two defined channel plans. It supports five different data rates (11 to 55 Mb/s). The base uncoded PHY rate is 22 Mb/s5.5. HomeRFHomeRF [15] working group was formed to develop a standard for wireless data communication between personal computers and consumer electronics in a home environment. The HomeRF standard is technically solid, simple, secure, and is easy to use. HomeRF networks provide a range of up to 150 ft typically enough for home networking. HomeRF uses Shared Wireless Access Protocol (SWAP) to provide efficient delivery of voice and data traffic. SWAP uses a transmit power of up to 100 mW and a gross data rate of 2 Mb/s. It can support a maximum of 127 devices per network. A SWAP-based system can work as an ad-hoc network or as a managed network using a connection point6. CONCLUSIONIn this paper, we presented an overview of UWB technology and its characteristics and advantages over conventional, continuous wave transmissions. We presented how UWB is well suited for several applications like sensor networks and MANETs. UWB technology has garnered a lot of interest among vendors who are looking at standardizing the use of the technology in various forums including IEEE.中文翻译超宽带系统的数据通信G. Racherla, J.L. Ellis, D.S. Furuno, S.C. LinGeneral Atomics, Advanced Wireless Group10240 Flanders Ct.San Diego CA 92121E-mail: {gopal.racherla, jason.ellis, susan.lin,超宽带（UWB）是一种在宽频谱范围内使用超低功耗传播无线脉冲能量的无线电传输方案。
通信工程移动通信中英文对照外文翻译文献
中英文翻译(文档含英文原文和中文翻译)附件1：外文资料翻译译文通用移动通信系统的回顾1.1 UMTS网络架构欧洲/日本的3G标准，被称为UMTS。
UMTS是一个在IMT-2000保护伞下的ITU-T 批准的许多标准之一。
随着美国的CDMA2000标准的发展，它是目前占主导地位的标准，特别是运营商将cdmaOne部署为他们的2G技术。
在写这本书时，日本是在3G 网络部署方面最先进的。
三名现任运营商已经实施了三个不同的技术：J - PHONE 使用UMTS，KDDI拥有CDMA2000网络，最大的运营商NTT DoCoMo正在使用品牌的FOMA（自由多媒体接入）系统。
FOMA是基于原来的UMTS协议，而且更加的协调和标准化。
UMTS标准被定义为一个通过通用分组无线系统（GPRS）和全球演进的增强数据技术（EDGE）从第二代GSM标准到UNTS的迁移，如图。
这是一个广泛应用的基本原理，因为自2003年4月起，全球有超过847万GSM用户，占全球的移动用户数字的68％。
重点是在保持尽可能多的GSM网络与新系统的操作。
我们现在在第三代（3G）的发展道路上，其中网络将支持所有类型的流量：语音，视频和数据，我们应该看到一个最终的爆炸在移动设备上的可用服务。
此驱动技术是IP协议。
现在，许多移动运营商在简称为2.5G的位置，伴随GPRS的部署，即将IP骨干网引入到移动核心网。
在下图中，图2显示了一个在GPRS网络中的关键部件的概述，以及它是如何适应现有的GSM基础设施。
SGSN和GGSN之间的接口被称为Gn接口和使用GPRS隧道协议（GTP的，稍后讨论）。
引进这种基础设施的首要原因是提供连接到外部分组网络如，Internet或企业Intranet。
这使IP协议作为SGSN和GGSN之间的运输工具应用到网络。
这使得数据服务，如移动设备上的电子邮件或浏览网页，用户被起诉基于数据流量，而不是时间连接基础上的数据量。
通信工程外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)计算机网络冗余GPS时间同步电路板的设计与实现摘要：如今，在计算机网络系统中准确和可靠的时间是一个基本要求。
为实现这一必要性，时间同步想法产生了。
同时在某些情况下，可靠的时间是如此的重要，以致于一个冗余的结构得以应用。
在本文中，时间同步系统的主要研究是设计和实施一个时间同步电路，该电路能够通过NTP协议与计算机网络同步时间。
在本设计中还嵌入了冗余方案以便提供更高的可靠性。
关键字：计算机网络GPS时间NTP 冗余时间同步时间同步协议时间服务器1. 引言我们通常会把电脑的时间和手表的误差设置在一两分钟内，但另一方面，准确和可靠的时间对于财务和法律事务、运输、分销系统，和许多其他涉及资源分布广泛的应用程序是必要的。
举一个例子说明，在一个分布式的机票预订系统，如果分布式计算机时间不同，座椅可以卖出两倍价格甚至更多，或者在网上股票交易完成之前会产生法律后果。
在这方面，世界协调时和时钟同步已开发出来。
基础的时间尺度已随着历史得到改进，以地球自转为基础的地球时和原子时也产生了。
一些重要的时间尺度还包括国际原子时（TAI）、通用协调时间尺度（UTC）、和标准时间或民用时间。
时钟同步协议的想法是，即使最初设置准确，但电脑的内部时钟也可能与世界时钟不同。
之后，由于时钟漂移，会有相当大的误差，所以总是有必要将这些漂移的时钟同步到参考时钟源。
时间同步源包括地球上的无线电同步技术（WWV, WWVH, WWVB, DCF77 and LORAN-C）、卫星时间同步技术（GOES, GPS, GLONASS, and Galileo）、互联网时间同步技术以及电话拨号时间同步技术。
在这些时钟源中，全球定位系统（GPS）提供了一些特殊的优点，如时间精度、抗噪声干扰、在世界各地都可用、并不断引用国际标准。
如今，相比其他时钟资源，全球定位系统时钟的使用更为广泛。
图1显示了一个典型的时间同步结构，其中时间服务器从GPS接收的数据作为时间同步源。
通信专业外文翻译
通信工程专业毕业设计外文资料翻译第1 页正交频分复用技术简介可以减少子信道之间的相互干扰。
每个利用在容易受外界干扰或者抵抗外界干扰能力较差的传输介质中。
目前正交频分复用技称的数字用户环路、欧洲电信标准协会的数字音频广播、数字视频广播、高清晰度电视、无线局域网等。
40纪60年代就已经有人提出了使用平行数据传输和频分复用的概念。
70正交的子载波以及从子载波中恢复原信号的问题。
这就解决了多载波传输系统发送和传送的难题。
应用快速傅里叶变换和快速傅里叶逆变换更是使多载波传输系统的复杂度大大降低。
从此正交频分复用技术开始走向实用。
但是应用正交频分复用系统仍然需要大机振荡器的稳定性以及射频功率放大器的线性要求等因素也是正交频分复用技术实现的制约条件。
因此正交频分复用技术迟迟没有得到迅速发展。
80进入901999程师协会通过了一个的无线局域网标准IEEE802.lla54Mbps25Mbps的无线A TM接口和10Mbps能满足室内、室外的各种应用场合。
欧洲电信组织的宽带射频接入网的局域网标准通信工程专业毕业设计外文资料翻译第 2 页HiperiLAN2也把正交频分复用定为它的物理层标准调制技术。
正交频分复用有许多关键技术。
12息也必须不断的传送。
二是既有较低的复杂度又有良好的导频跟踪能力的信道估计器的计器的性能与导频信息的传输方式有关。
3码和交织是通常采用的方道特性信息已经被正交频分复用这种调制方式本身所利用了。
但是正交频分复用系统的4N个正交子载波信号的叠N值功率是平均功率的N分复用系统的性能大大下降甚至直接影响实际应用。
为了解决这一问于信号畸变技术、信号扰码技术和基于信号空间扩展等降低正交频分复用系统峰均功率比的方法。
11000个通信工程专业毕业设计外文资料翻译第3 页了这种特殊的信号穿透能力使得正交频分复用技术深受欧洲通信营运商以及手机生产商的喜爱和欢迎。
(2) 正交频分复用技术能够持续不断地监控传输介质上通信特性的突然变化。
通信工程专业英语论文
通信工程专业英语论文外文翻译(原文)The General Situation of AT89C51The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash Programmable and Erasable Read Only Memory (PEROM) and 128 bytes RAM. The device is manufactured using Atmel’s high density nonvolatilememory technology and is compatible with the industry standard MCS-51?instruction set and pin out. The chip combines a versatile 8-bit CPU with Flash on a monolithic chip; the Atmel AT89C51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.Features:• Compatible with MCS-51? Products• 4K Bytes of In-System Reprogrammable Flash Memory• Endurance: 1,000 Write/Erase Cycles• Fully Static Operatio n: 0 Hz to 24 MHz• Three-Level Program Memory Lock• 128 x 8-Bit Internal RAM• 32 Programmable I/O Lines• Two 16-Bit Timer/Counters• Six Interrupt Sources• Programmable Serial Channel• Low Power Idle and Power Down ModesThe AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. 1外文翻译(原文)The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power Down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions until the next hardware reset.Block DiagramPin Description:VCC Supply voltage.GND Ground.Port 0:Port 0 is an 8-bit open drain bidirectional I/O port. As an output port eachpin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high impedance inputs. (Sink/flow) Port 0 may also be configured to be the multiplexed low order address/data bus during accesses to external program and data memory. In this mode P0 has 2外文翻译(原文)internal pull-ups.Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during program verification. External pull-ups are required during program verification.Port 1:Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups.Port 1 also receives the low-order address bytes during Flash programming and verification.Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 Port 2:output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups.Port 2 emits the high-order address byte during fetches fromexternal program memory and during accesses to external data memory that uses 16-bit addresses (MOVX @ DPTR). In this application it uses strong internal pull-ups when emitting 1s. During accesses to external datamemories that use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register.Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.Port 3:Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups.3外文翻译(原文)Port 3 also serves the functions of various special features of the AT89C51 as listed below:Port 3 also receives some control signals for Flash programming and verification.RST:Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device.ALE/PROG:Address Latch Enable output pulse for latching the low byte of theaddress during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clockingpurposes. Note, however, that one ALE pulse is skipped during each access to external Data Memory.If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in externalexecution mode.PSEN:Program Store Enable is the read strobe to external program memory. When the AT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.4外文翻译(原文)EA/VPP:External Access Enable. EA must be strapped to GND in orderto enable the device to fetch code from external program memorylocations starting at 0000H up to FFFFH. Note, however, that if lock bit 1(LB1) is programmed, EA will be internally latched (fasten with a latch) on reset.EA should be strapped to VCC for internal program executions.This pin also receives the 12-volt programming enable voltage(VPP) during Flashprogramming, for parts that require 12-volt VPP.XTAL1:Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2:Output from the inverting oscillator amplifier.Oscillator Characteristics:XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2. There are no requirements on the duty cycle of the external clock signal, since the input to the internal clockingcircuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low times specifications must be observed.Idle Mode:In idle mode, the CPU puts itself to sleep while all theon chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registersremain unchanged during this mode. The idle mode can be terminated byany enabled interrupt or by a hardware reset.It should be noted that when idle is terminated by a hard ware reset, the device normally resumes program execution, from where it left off,up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate thepossibility of an unexpected write to a port pin when Idle is terminated by reset, the instruction following the one that invokes Idle 5 外文翻译(原文)should not be one that writes to a port pin or to external memory.Power Down ModeIn the power down mode the oscillator is stopped, and theinstruction that invokes power down isthe last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power down mode is terminated. The only exit from power down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.Program Memory Lock BitsOn the chip are three lock bits which can be left unprogrammed (U)or can be programmed (P) to obtain the additional features listed in the table below:When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during reset. If the device is powered up without a reset, the latch initializes to a random value, and holds that value until reset is activated. It is6外文翻译(原文)necessary that the latched value of EA be in agreement with the current logic level at that pin in order for the device to function properly.Programming the Flash:The AT89C51 is normally shipped with the on-chip Flashmemory array in the erased state (that is, contents = FFH) and ready to be programmed. The programming interface accepts either a high-voltage (12-volt) or alow-voltage (VCC) program enable signal. The low voltage programming mode provides a convenient way to program the AT89C51 inside the user’s system, whilethe high-voltage programming mode is compatible with conventional third party Flash or EPROM programmers.The AT89C51 is shipped with either the high-voltage or low-voltage programming mode enabled. The respective top-side marking and device signatureThe AT89C51 code memory array is programmed byte-bybyte in either programming mode. To program any nonblank byte in the on-chip Flash Programmable and Erasable Read Only Memory, the entire memory must be erased using the Chip Erase Mode.Programming Algorithm: Before programming the AT89C51, the address, data and control signals should be set up according to the Flash programming mode table and Figures 3 and 4. To program the AT89C51, take the following steps.1. Input the desired memory location on the address lines.2. Input the appropriate data byte on the data lines.3. Activate the correct combination of control signals.4. Raise EA/VPP to 12V for the high-voltage programming mode.7外文翻译(原文)5. Pulse ALE/PROG once to program a byte in the Flash array or thelock bits. The byte-write cycle is self-timed and typically takes nomore than 1.5 ms. Repeat steps 1 through 5, changing the address anddata for the entire array or until the end of the object file is reached.Data Polling: The AT89C51 features Data Polling to indicate the endof a write cycle. During a write cycle, an attempted read of the lastbyte written will result in the complement of the written datum on PO.7. Once the write cycle has been completed, true data are valid on all outputs, and the next cycle may begin. Data Polling may begin any time after a write cycle has been initiated.Ready/Busy: The progress of byte programming can also be monitoredby the RDY/BSY output signal. P3.4 is pulled low after ALE goes high during programming to indicate BUSY. P3.4 is pulled high again when programming is done to indicate READY.Program Verify: If lock bits LB1 and LB2 have not been programmed,the programmed code data can be read back via the address and data lines for verification. The lock bits cannot be verified directly.Verification of the lock bits is achieved by observing that theirfeatures are enabled.Chip Erase: The entire Flash Programmable and Erasable Read Only Memory array is erased electrically by using the proper combination of control signals and byholding ALE/PROG low for 10 ms. The code array is written with all “1”s. The chiperase operation must be executed before the code memory can be re-programmed.Reading the Signature Bytes: The signature bytes are read by the same procedure asa normal verification of locations 030H, 031H, and 032H, except that P3.6 and P3.7must be pulled to a logic low. The values returned are as follows.(030H) = 1EH indicates manufactured by Atmel(031H) = 51H indicates 89C51(032H) = FFH indicates 12V programming(032H) = 05H indicates 5V programming8外文翻译(原文)Programming InterfaceEvery code byte in the Flash array can be written and the entire array can be erasedby using the appropriate combination of control signals. The write operation cycle isselftimed and once initiated, will automatically time itself to completion.9单片机温度控制系统中英文翻译资料AT89C51的概况AT89C51是美国ATMEL公司生产的低电压，高性能CMOS8位单片机，片内含4Kbytes的快速可擦写的只读程序存储器(PEROM)和128 bytes 的随机存取数据存储器(RAM)，器件采用ATMEL公司的高密度、非易失性存储技术生产，兼容标准MCS-51产品指令系统，片内置通用8位中央处理器(CPU)和flish 存储单元，功能强大AT89C51单片机可为您提供许多高性价比的应用场合，可灵活应用于各种控制领域。
通信工程类外文翻译、中英文翻译、外文文献翻译
宽带，稳定增益，FET输入的运算放大器特征：●400MHz稳态增益带宽●低输入偏置电流:5pA●高输入电阻:1012Ω或1.0pF●极低的dG/dP :0.006%/0.009°●低扭曲:在5MHz为90dB●快速设置：17ns(0.01%)●高输出电流：60mA●超速传动快速恢复应运：●宽带光电二极管放大器●峰值检测●CCD输出缓冲器●ADC输入缓冲器●高速积分仪●检测和测量前端宽带光电二极管转移阻抗放大器一种包含宽带，稳态增益，电压反馈运算OPA655，当有FET输入时，能为ADC 缓冲器和转移阻抗设备提供十分宽广的动态放大范围。
良好的脉冲设置和极低的调和扭曲将支持更高要求的ADC输入缓冲需要。
宽带稳态增益和FET输入在高速，低噪声积分器中允许特殊的操作。
由FET输入所提供的高输入阻抗和低偏置电流能被极低的输入电压噪声支持，在宽带光电二极管设备中达到极低的积分噪声。
给定的OPA655高达240MHZ的增益带宽产品可以提供高宽带转移阻抗。
如下图所示，来自于47PF 的电容高达1兆欧的转移阻抗可以提供1MHZ，-3增益的带宽。
性能讨论：使用FET输入阻抗的放大器具有同那些用biploar阻抗相似的功能外，还有一些重要的优点。
在标准运算中，低输入偏置电流可以减少由于一个非常高或者未知源的阻抗所产生的直流电压错误。
在绝大多数OPA655使用中，输出直流错误只是由于低于1mv输入激励电压所造成的。
类似地，输入电流噪声几乎对输出电流噪声影响很小。
对于低电流噪声和低于6nv/ 输入电压噪声的OPA655对于宽带阻抗的应用极为有益。
OPA655的高宽带增益和近乎线性的输出，可以通过5MHz对于2v的峰值电压摆动在100Ω处，来控制调和扭曲低于-90dbc.在低频率或高负载阻抗时，这种显著地减少扭曲可以被观察到。
图1 放大器的内部原理操作时需考虑的问题对于PC板外形的仔细观察可以实现如典型性能曲线中所示的特殊操作。
通信工程 网络技术 外文翻译 文献翻译 外文文献
外文翻译译文题目：在WDM代理网络中基于蚁群的动态路由和波长分配原稿题目：Dynamic Routing and Wavelength Assignment in WDM Net- works with Ant-Based AgentsEmbedded and Ubiquitous Compter science V olume 3207.200 原稿出处：4.pp 829-838在WDM代理网络中基于蚁群的动态路由和波长分配【摘要】在这篇论文中，我们提出一种在波长连续性约束波分复用（WDM）光网络中基于蚁群算法的动态路由与波长分配。
通过采用一个新的路由表结构和保持大量的蚂蚁在网络中合作探索网络状态和不断更新路由表的方式，我们新的蚁群算法能够有效地支持蚁群觅食任务的路由选择波分复用（WDM）网络中波长分配，并允许一个连接设置迅速到达小的设置时间。
大量基于ns-2网络仿真结果模拟表明，该算法能够很好得适应流量变化和达到一个比起固定路由算法较低的阻塞概率。
【关键词】路由，波长分配，算法，WDM（波分复用），蚁群算法1.介绍所有采用波分复用（WDM）光网络都有一个巨大的带宽容量，他们显示成为下一代互联网骨干。
在所有光网络中，数据路由在光学通道被叫做光路。
路由和波长分配（RWA）问题是如何为一个连接请求确定路由和波长。
没有了波长转换功能，一个光路必须在所有链接中使用相同的波长，这被称为波长连续性限制。
路由和波长分配(RWA)问题通常被归类为静态和动态两种。
在静态路由和波长分配问题中，连接请问是预先给出的，问题就变成如何为所有请求建立光路，使得总数量的波长被最小化。
静态路由和波长分配问题已经被证明是一个NP完全问题。
在动态路由和波长分配问题中，流量是动态的以及连接请求到达的随机性使得它变得更为困难。
启发式算法通常被用来解决这个问题。
一般来说，一个动态的路由和波长分配算法的目的是使在整个网络中总阻塞概率最小化。
通信毕设中英文文献翻译
英文文献The Application of one point Multiple Access Spread SpectrumCommunication SystemLiu Jiangang, Nan yang City, Henan Province Electric Power Industry Bureau【ABSTRACT】Spread Spectrum Digital Microwave communication as a communication, because their excellent performance have been widely used. The article in Nan yang City Power Industry Bureau one point Multiple Access Spread Spectrum Communication System as an example. briefed the spread spectrum communications, the basic concept and characteristics of the power system communication applications.KEYWORDS：one point multiple access; Spread-spectrum communication; AttenuationNan yang City in the outskirts of Central cloth 35 to 11 kv substation farm terminals, their operation management rights belong to the Council East, Rural Power Company west (the eastern suburb of agricultural management companies -- four, the western suburbs of Rural Power Company Management 7), Scheduling of the various stations of the means of communication to the original M-150 radio and telephone posts. 2002 With the transformation of rural network, the remote station equipment into operation and communication channels to put a higher demand .As PUC Dispatch Communication Building to the east and west of farmers -- the difference between a company linked to fiber, Therefore, if 11 substations and the establishment of a transfer Link Building links Point may be the data and voice were sent to two rural power companies dispatch room, Rural Network scheduling for the implementation of automation to create the necessary conditions.Given the status and power grid substation level, nature, taking into account the carrier and optical-fiber communications to conduct multiple forwarding, increasing the instability factor, considering the cost and conditions of the urban construction, Finallydecided to adopt wireless spread-spectrum technology to establish that 11 farm terminal substation communication system. This paper describes the spread spectrum technology and the current system of the building.1.The basic concept of spread-spectrum communication.Spread Spectrum Communication's basic characteristics, is used to transmit information to the signal bandwidth (W) is far greater than the practical information required minimum (effective) bandwidth (△ F) , as the ratio of processing gain GP .G P = W/△FAs we all know, the ordinary AM, FM, or pulse code modulation communications, GP values in the area more than 10 times, collectively, the "narrow-band communication", and spread-spectrum communications GP values as high as hundreds or even thousands of times, can be called "broadband communications."Due to the spread-spectrum signal, it is very low power transmitters, transmission space mostly drowned in the noise, it is difficult to intercepted by the other receiver, only spreading codes with the same (or random PN code) receiver, Gain can be dealt with, and dispreading resume the original signal.2.The technology superiority of spread-spectrum communication.Strong anti-interference, bit error rate is low. As noted above, the spread spectrum communication system due to the expansion of the transmitter signal spectrum, the receiver dispreading reduction signal produced spreading gain, thereby greatly enhancing its interference tolerance. Under the spreading gain, or even negative in the signal-to-noise ratio conditions, can also signal from the noise drowned out Extraction, in the current business communications systems, spread spectrum communication is only able to work in a negative signal-to-noise ratio under the conditions of communication.Anti-multi-path interference capability, increase the reliability of the system. Spread-spectrum systems as used in the PN has a good correlation, correlation is very weak. different paths to the transmission signal can easily be separated and may in time and re-alignment phase, formation of several superimposed signal power, thereby improving the system's performance to receive increased reliability of the system.Easy to use the same frequency, improving the wireless spectrum utilization.Wireless spectrum is very valuable, although long-wave microwave have to be exploited, and still can not meet the needs of the community. To this end, countries around the world are designed spectrum management, users can only use the frequency applications, rely on the channel to prevent the division between the channel interference.Due to the use of spread-spectrum communication related receive this high-tech, low signal output power ( "a W, as a general-100 mW), and will work in the channel noise and thermal noise in the background, easy to duplicate in the same area using the same frequency, can now all share the same narrow-band frequency communications resources.Spread spectrum communication is digital communications, particularly for digital voice and data transmission while, spread spectrum communication with their own encryption, only in the same PN code communication between users, is good for hiding and confidential in nature, facilitating communications business . Easy to use spread-spectrum CDMA communications, voice compression and many other new technologies, more applicable to computer networks and digitization of voice, image information transmission.Communication is the most digital circuits, equipment, highly integrated, easy installation, easy maintenance, but also very compact and reliable. The average failure rate no time was very long.We have decided to adopt the spread-spectrum communication technology construction of 11 farm terminal substation communications system, Due to the spread-spectrum communication by the line-of-sight transmission distance restrictions, has become unstoppable system design premise.If the PUC scheduling Building and 11 substations have stopped, and the problem becomes more complicated, use spread spectrum system on the feasibility greatly reduced. Therefore, we look at the city Aerial topographical map, initially identified has not stopped to consider systems design, and requests the companies used this equipment Spread Spectrum 11 points transmission routing of the measured and the results have been satisfactory.Then spread spectrum wireless equipment market supply of cash, initially, weselected a series of Spread Spectrum Comlink third generation products. Because most of the point-to-point mode, Merit functions of the spread-spectrum equipment in a point-to-multipoint application environments encountered many problems: First is the issue of frequency resources. Even a minimum of 64 kbit / s data rate radio, space also occupied bandwidth 5 MHz, Because 32 of the PN code isolation is only about 15 dBm, the project had to use frequency division multiple access 35 db to get around the theoretical isolation. 11 stations will use 11 frequencies, frequency greater waste of resources. Comlink and Spread Spectrum products in the same frequency to achieve a point-to-multipoint communications.Second antenna erection problems, point-to-point equipment for the main radio station, the main station need to set up a number of terminal antennas, the vast majority of domestic engineering companies used by the U.S. Conifer 24 dBi parabolic semi-cast magnesium grid directional antenna. vertical polarization - 1 m wide, it is difficult to top the layout and avoid flap and the mutual interference, Although the project can be set up to take stratified, or through cooperation and on the road to one or more Omni directional antenna launch, However, as construction of a road and the signal attenuation, transmission result is not satisfactory.In addition, the RF cable lying, The application of network management software such factors we have also decided to adopt the final 1:00 Comlink Multiple Access Spread Spectrum products. Its system configuration, as shown in Figure 2:3.Routing AnalysisCombining visual distance access and use the radio and antenna gain, cable attenuation and environmental factors, and testing the design is reasonable, determinethe attenuation affluent channel capacity. Spread spectrum microwave link attenuation depends on the reliability margin.Attenuation margin calculation formula : F G= G SG + G ANT - L GL - L PLF G——Attenuation margin ；G SG——System Gain (dB）；G ANT——Antenna Gain (dBi）；L GL——Connectors and cables attenuation (dB)；L pL—— Channel attenuation (dB）。
通信工程外文文献
外文资料与中文翻译外文资料：Review of UMTS1.1 UMTS Network ArchitectureThe European/Japanese 3G standard is referred to as UMTS. UMTS is one of a number of standards ratified by the ITU-T under the umbrella of IMT-2000. It is currently the dominant standard, with the US CDMA2000 standard gaining ground, particularly with operators that have deployed cdmaOne as their 2G technology. At time of writing,Japan is the most advanced in terms of 3G network deployment. The three incumbent operators there have implemented three different technologies: J-Phone is using UMTS,KDDI has a CDMA2000 network, and the largest operator NTT DoCoMo is using a system branded as FOMA (Freedom of Multimedia Access). FOMA is based on the original UMTS proposal, prior to its harmonization and standardization.The UMTS standard is specified as a migration from the second generation GSM standard to UMTS via the General Packet Radio System (GPRS) and Enhanced Data for Global Evolution (EDGE), as shown in Figure. This is a sound rationale since as of April 2003, there were over 847 Million GSM subscribers worldwide1, accounting for68% of the global cellular subscriber figures. The emphasis is on keeping as much ofthe GSM network as possible to operate with the new system.We are now well on the road towards Third Generation (3G), where the network will support all traffic types: voice, video and data, and we should see an eventual explosion in the services available on the mobile device. The driving technology for this is the IP protocol. Many cellular operators are now at a position referred to as 2.5G, with the deployment of GPRS, which introduces an IP backbone into the mobile core network.The diagram below, Figure 2, shows an overview of the key components in a GPRS network, and how it fits into the existing GSM infrastructure.The interface between the SGSN and GGSN is known as the Gn interface and uses the GPRS tunneling protocol (GTP, discussed later). The primaryreason for the introduction of this infrastructure is to offer connections to external packet networks, such as the Internet or a corporate Intranet.This brings the IP protocol into the network as a transport between the SGSN and GGSN. This allows data services such as email or web browsing on the mobile device,with users being charged based on volume of data rather than time connected.The dominant standard for delivery of 3G networks and services is the Universal Mobile Telecommunications System, or UMTS. The first deployment of UMTS is the Release ’99 architecture, shown below in F igure 3.In this network, the major change is in the radio access network (RAN) with the introduction of CDMA technology for the air interface, and ATM as a transport in the transmission part. These changes have been introduced principally to support the transport of voice, video and data services on the same network. The core network remains relatively unchanged, with primarily software upgrades. However, the IP protocol pushes further into the network with the RNC now communicating with the 3G SGSN using IP.The next evolution step is the Release 4 architecture, Figure 4. Here, the GSM core is replaced with an IP network infrastructure based around Voice over IP technology.The MSC evolves into two separate components: a Media Gateway (MGW) and an MSC Server (MSS). This essentially breaks apart the roles of connection and connection control. An MSS can handle multiple MGWs, making the network more scaleable.Since there are now a number of IP clouds in the 3G network, it makes sense to merge these together into one IP or IP/ATM backbone (it is likely both options will be available to operators.) This extends IP right across the whole network, all the way to the BTS.This is referred to as the All-IP network, or the Release 5 architecture, as shown in Figure 5. The HLR/VLR/EIR are generalised and referred to as the HLR Subsystem(HSS).Now the last remnants of traditional telecommunications switching are removed, leaving a network operating completely on the IP protocol, and generalised for the transport of many service types. Real-time services are supported through the introduction of a new network domain, the IP Multimedia Subsystem (IMS).Currently the 3GPP are working on Release 6, which purports to cover all aspects not addressed in frozen releases. Some call UMTS Release 6 4G and it includes such issues as interworking of hot spot radio access technologies such as wireless LAN.1.2 UMTS FDD and TDDLike any CDMA system, UMTS needs a wide frequency band in which to operate to effectively spread signals. The defining characteristic of the system is the chip rate, where a chip is the width of one symbol of the CDMA code. UMTS uses a chip rate of 3.84Mchips/s and this converts to a required spectrum carrier of 5MHz wide. Since this is wider than the 1.25MHz needed for the existing cdmaOne system, the UMTS air interface is termed ‘wideband’ CDMA.There are actually two radio technologies under the UMTS umbrella: UMTS FDD and TDD. FDD stands for Frequency Division Duplex, and like GSM, separates traffic in the uplink and downlink by placing them at different frequency channels. Therefore an operator must have a pair of frequencies allocated to allow them to run a network, hence the term ‘paired spectrum’. TDD or Time Division Duplex requires only one frequency channel, and uplink and downlink traffic are separated by sending them at different times. The ITU-T spectrum usage, as shown in Figure 6, for FDD is 1920- 980MHz for uplink traffic, and 2110-2170MHz for downlink. The minimum allocation an operator needs is two paired 5MHz channels, one for uplink and one for downlink, at a separation of 190MHz. However, to provide comprehensive coverage and services, it is recommended that an operator be given three channels. Considering the spectrum allocation, there are 12 paired channels available, and many countries have now completed the licencing process for this spectrum, allocating between two and four channels per licence. This has tended to work out a costly process for operators, since the regulatory authorities in some countries, notably in Europe, have auctioned these licences to the highest bidder. This has resulted in spectrum fees as high as tens of billions of dollars in some countries.The Time Division Duplex (TDD) system, which needs only one 5MHz band in which to operate, often referred to as unpaired spectrum. The differences between UMTS FDD and TDD are only evident at the lower layers, particularly on the radio interface. At higher layers, the bulk of the operation of the two systems is the same. As the name suggests, the TDD system separates uplink and downlink traffic by placing them in different time slots. As will be seen later, UMTS uses a 10ms frame structure which is divided into 15 equal timeslots. TDD can allocate these to be either uplink or downlink,with one or more breakpoints between the two in a frame defined. In this way, it is well suited to packet traffic, since this allows great flexibility in dynamically dimensioning for asymmetry in traffic flow.The TDD system should not really be considered as an independent network,but rather as a supplement for an FDD system to provide hotspot coverage at higher data rates. It is rather unsuitable for large scale deployment due to interference between sites, since a BTS may be trying to detect a weak signal from a UE, which is blocked out by a relatively strong signal at the same frequency from a nearby BTS. TDD is ideal for indoor coverage over small areas.Since FDD is the main access technology being developed currently, the explanations presented here will focus purely on this system.1.3 UMTS Bearer ModelThe procedures of a mobile device connecting to a UMTS network can be split into two areas: the access stratum (AS) and the non-access stratum (NAS). The access stratum involves all the layers and subsystems that offer general services to the non-access stratum. In UMTS, the access stratum consists of all of the elements in the radio access network, including the underlying ATM transport network, and the various mechanisms such as those to provide reliable information exchange. All of the non-access stratum functions are those between the mobile device and the core network, for example, mobility management. Figure 7 shows the architecture model. The AS interacts with the NAS through the use of service access points (SAPs).UMTS radio access network (UTRAN) provides this separation of NAS and AS functions, and allows for AS functions to be fully controlled and implemented within the UTRAN. The two major UTRAN interfaces are the Uu, which is the interface between the mobile device, or User Equipment (UE) and the UTRAN, and the Iu, which is the interface between the UTRAN and the core network. Both of these interfaces can be divided into control and user planes each with appropriate protocol functions.A Bearer Service is a link between two points, which is defined by a certain set of characteristics. In the case of UMTS, the bearer service is delivered using radio access bearers.A Radio access bearer (RAB) is defined as the service that the access stratum (i.e.UTRAN) provides to the non-access stratum for transfer of user data between the User Equipment and Core Network. A RAB can consist of a number of subflows, which are data streams to the core network within the RAB that have different QoS characteristics,such as different reliabilities. A common example of this is different classes of bits with different bit error rates can be realised as different RAB subflows. RAB subflows are established and released at the time the RAB is established and released, and are delivered together over the same transport bearer.A Radio Link is defined as a logical association between a single User Equipment (UE) and a single UTRAN access point, such as an RNC. It is physically comprised of one or more radio bearers and should not be confused with radio access bearer.Looking within the UTRAN, the general architecture model is as shown in Figure 8 below. Now shown are the Node B or Base Station (BTS) and Radio Network Controller (RNC) components, and their respective internal interfaces. The UTRAN is subdivided into blocks referred to as Radio Network Subsystems (RNS), where each RNS consists of one controlling RNC (CRNC) and all the BTSs under its control. Unique to UMTS is the interface between RNSs, the Iur interface, which plays a key role in handover procedures. The interface between the BTS and RNC is the Iub interface.All the ‘I’ interfaces: Iu, Iur and Iub, currently3 use ATM as a transport layer. In the context of ATM, the BTS is seen as a host accessing an ATM network, within which the RNC is an ATM switch. Therefore, the Iub is a UNI interface, whereas the Iu and Iur interfaces are considered to be NNI, as illustrated in Figure 9.This distinction is because the BTS to RNC link is a point-to-point connection in that a BTS or RNC will only communicate with the RNC or BTS directly connected to it, and will not require communication beyond that element to another network element.For each user connection to the core network, there is only one RNC, which maintains the link between the UE and core network domain, as highlighted in Figure 10. This RNC is referred to as the serving RNC or SRNC. That SRNC plus the BTSs under its control is then referred to as the SRNS. This is a logical definition with reference to that UE only. In an RNS, the RNC that controls a BTS is known as the controlling RNC or CRNC. This is with reference to the BTS, cells under its control and all the common and shared channels within.As the UE moves, it may perform a soft or hard handover to another cell. In the case of a soft handover, the SRNC will activate the new connection to the new BTS. Should the new BTS be under the control of another RNC, the SRNC will also alert this new RNC to activate a connection along the Iur interface. The UE now has two links, one directly to the SRNC, and the second, through the new RNC along the Iur interface. In this case, this new RNC is logically referred to as a drift RNC or DRNC, see Figure 10. It is not involved in any processing of the call and merely relays it to the SRNC for connection to the core. In summary, SRNC and DRNC are usually associated with the UE and the CRNC is associated with the BTS. Since these are logical functions it is normal practicethat a single RNC is capable of dealing with all these functions.A situation may arise where a UE is connected to a BTS for which the SRNC is not the CRNC for that BTS. In that situation, the network may invoke the Serving RNC Relocation procedure to move the core network connection. This process is described inSection 3.中文翻译：通用移动通信系统的回顾1.1 UMTS网络架构欧洲/日本的3G标准，被称为UMTS。