模拟电路和信号处理_英文资料翻译中英对照

1、 英文原文xDSLAnalog Circuits and Signal Processing xDSL refers to different DSL such as ADSL HDSL and RADSL DSL uses ordinary telephone lines to high-bandwidth information into the home and small business enterprise technologies Traditional telephone business through the twisted-pair families or compani

2、es connected with the telephone company Input devices such as access to telephone voice signal analog signal it will be transformed into electrical signals Because the telephone companys signal has been set to use analog signal transmission so easily on the phone and exchange of information between

3、the phone company That is why the need to use a computer modem reasons so that it will be the value of analog signal and converted to digital signals DSL will not assume that digital signal and then back into analog signals Digital signal directly in the form of digital transmission to the computer

4、which allows phone companies to greater bandwidth to transmit information At the same time part of the signal is still analog signal transmission in order to use the phone at the same time DSL including ADSL CDSL DSL Lite HDSL IDSL RADSL SDSL UDSL VDSL x2DSL1 Outline xDSL is a DSL Digital Subscriber

5、 Line of collectively that is digital subscriber line based on copper telephone lines for transmission of point-to-point transmission medium DSL technology in the traditional telephone network POTS users loops symmetrical support and asymmetric transfer mode often resolved in the network service pro

6、viders and end-users among the "last mile" of transmission bottlenecks Because of the large number of users has been laying loop so to make full use of existing resources of copper twisted-pair copper through the high-speed access has become the minimum cost of doing business delivered the

7、 most realistic solution for broadband access networks DSL technology has been a large number of applications is a very mature technology access System is mainly composed of xDSL central office equipment DSLAM-Digital Subscriber Line Access Multiplexer and customer premise equipment CPE from the cen

8、tral office DSLAM access platform DSL central office card voice separator IPC data convergence device and so on Composition As shown voice separator will be on the line and high-frequency digital audio signal modulation signal separation and audio signals into the telephone exchange high-frequency s

9、ignals into digital modulation DSL access system DSLAM access platform can be inserted at the same time different DSL access Network cards and cards central office line cards will be on the signal modulation for digital signal and provides data transfer interface IPC for DSL access system to provide

10、 different WAN interfaces such as ATM Frame Relay T1E1 and so on These facilities are located in the telephone switch systems in the room DSL Modem by the user equipment and voice component separator DSL Modem users on the packet modulation and demodulation and provides data transfer interface 2 DSL

11、 modulation techniques DSL technology is the use of the phone system not being used for high-frequency signals to transmit data DSL use of more advanced modulation techniques At present the widely used ADSL modulation technology 3 QAM quadature amplitude modulation CAP carrierless amplitude-phase mo

12、dulation DMT discrete multitone which the DMT modulation technology ANSI Subcommittee T1E14 standardized the development of the country Standard used However due to the introduction of the standards will not be long there are still a considerable number of ADSL products using CAP or QAM modulation Q

13、AM modulation technology to achieve the following methods sending data bits symbol encoder has been divided into two the rate for the original 1 2 with a pair of orthogonal modulation weight multiplied after the summation output Compared with other modulation QAM coding has to make full use of bandw

14、idth and strong anti-noise advantages QAM for ADSL main problem is how to adapt to different telephone lines between the performances of a larger difference To obtain a more desirable characteristics of the work QAM receiver and a transmitter with the same frequency and phase characteristics of the

15、input signal for decoding QAM receiver to use adaptive equalizer to compensate for the transmission signal distortion produced by the use of QAMs ADSL systems from the complexity of its adaptive equalizer CAP is based on QAM modulation technology developed you can say it is a variant of QAM technolo

16、gy Enter data into the encoder encoder within m-bit input has been mapped for k 2m different complex symbols An an jbn by the K different symbols constitute plural k-CAP line coding And an encoded bn respectively were sent to in-phase and quadrature digital shaping filter after the summation into th

17、e D A converter as the final low-pass filter signal sent CAP technology for ADSL is the main technical difficulties to overcome on the local signal crosstalk interference General crosstalk can be offset through the use of local or proximal crosstalk equalizer to resolve this problem DMT modulation t

18、echnology the main principle is to band 0-1104MHZ divided into 256 by the instructions of orthogonal frequency channel one for each channel bandwidth occupied by 4KHZ after a bit of the input signal distribution and caching will enter data into bits Block the TCM code for 512 points after the discre

19、te Fourier transform IDFT will transform into time-domain signal then bit block will be converted to 256-QAM characters Then each bit block add cyclic prefix for the elimination of ISI the data conversion module DA and send the signal sent to filter channel On the contrary at the receiving end in or

20、der to carry out decoding receive3 DSL classificationSymmetric DSL technology as follows1HDSL high bit-rate DSL HDSL is xDSL technology in the most mature one has been more widely used The technology can be available to full-duplex twisted-pair copper T1 or E1 transmission way It features two pairs

21、of twisted-pair transmission N × 64kbps to support a variety of speeds up to E1 rates HDSL is an alternative to T1E1 technology mainly used to connect digital switches high-bandwidth video conferencing distance learning cellular phone base station to connect such as the establishment of private

22、 networks And traditional T1E1 technology HDSL has the following advantages lower prices easy to install T1E1 request every 09 to 18 kilometers on the installation of an amplifier and HDSL in the 36 km distance transmission without amplifiers2SDSL - Single-line DSL which is one-way version of HDSL w

23、hich can provide two-way high-speed variable bit rate connection speeds ranging from 160Kbps to 2084Mbps It features a one-on twisted pair rate to support multiple T1E1 users based on the data flow to choose the most appropriate rate of the economy the rate of up to E1 HDSL than saving a pair of cop

24、per wire 04 mm twisted pair of the largest transmission distance of 3 km3MVL-Multiple Virtual Line its characteristics are as follows use a pair of twisted-pair easy to install inexpensive low-power high-density can be installed the use of ISDN technology with the same frequency the same cable signa

25、l interference with other Very small support the transmission of voice no voice in the client separator support at the same time on the same line to connect up to 8 MVL user equipment dynamic bandwidth allocation up down-sharing rate of up to 768Kbps transmission distance of up to 7 km32 Asymmetric

26、DSL TechnologyAsymmetric DSL technology as follows1ADSL - Asymmetric DSL asymmetric DSL ADSL networks to speed up the flow from the 1M and 8M down the traffic at the same time with an online offer voice telephone services Characterized by a pair of twisted-pair transmission up from the rate of up to

27、 1M down as much as 8M at the same time support the transmission of data and voice2RADSL - Rate Adaptive DSL rate adaptive DSL this technology allows service providers to adjust bandwidth xDSL connections in order to meet the actual needs and solve quality problems and long lines Its characteristics

28、 are as follows use a pair of twisted-pair transmission support synchronous and asynchronous transfer mode adaptive rate down from a rate of 640Kbps to 12Mbps up from the rate of 128Kbps to 1Mbps at the same time support the transmission of data and voice3VDSL - Very High Data Rate DSL VDSL and ADSL

29、 systems can make use of ordinary copper telephone without affecting the narrow-band voice services POTS ISDN high-speed data transmission business VDSL system and structure is very similar to ADSL VDSL used in a wide spectrum up to 12MHz The scope of the spectrum can be divided into a number of dow

30、nstream DS and upstream US band the band commonly used in international division of the way Band Plan there are mainly two Plan 997 Plan 998 Plan998 under the North American division of business needs mainly business-oriented asymmetric Plan997 and according to business needs into Europe mainly busi

31、ness-oriented symmetric ADSL as a result of the use of spectrum to only the highest 11MHz comparison VDSL can provide higher transmission speed more flexibility for different business needs to provide different transmission capacity of course transmission distance generally shorter than ADSLVDSL app

32、lication environment can be divided into three categories 1 short-range high-speed asymmetric operations for example less than 300m downlink transmission rate 26Mb s and above can be mainly used for video transmission 2 distance in symmetrical or asymmetrical close to the business For example about

33、1km symmetry 10Mb s 3 asymmetric long distance business this time as a result of high-frequency attenuation part of the larger lower rate up VDSL technology best suited to users in a relatively intensive short copper areas to provide high-speed data access business so in the East Asian countries suc

34、h as South Korea Japan to promote the application of constant in our country have been equipment manufacturers and operators The concern is to promote stage4 xDSL technology application41 Symmetric DSL technology Symmetric DSL technology used to replace traditional T1E1 access technology and traditi

35、onal T1E1 access compared to DSL technology has a line of low-quality simple installation and so on Widely used in communications network interconnection and other areas of campus through the technique can send multiple voice video and data42 Asymmetric DSL Technology Asymmetric DSL technology is id

36、eal for two-way bandwidth requirements of different applications such as Web browsing multimedia-on-demand information dissemination it is applied to Internet access VOD system汉语翻译xDSL模拟电路和信号处理 xDSL指的是不同的DSL如ADSLHDSL和RADSLDSL是用普通电话线将高带宽信息带进家庭和小型商业企业的技术传统电话业务通过双绞线将家庭或公司与电话公司相连输入设备如电话机获得声音信号为模拟信号将它转变为

37、电信号因为电话公司的信号已经设置成使用模拟信号传输所以很容易在电话和电话公司之间交换信息这就是为什么计算机需要使用调制解调器的原因使它能够获得模拟信号并按值转换为数字信号 DSL假定不用将数字信号再变回模拟信号数字信号直接以数字的形式传输到计算机这就使得电话公司能够以更大的带宽来传输信息同时一部分信号仍然是模拟信号传输以便使于同时使用电话 DSL包括ADSLCDSLDSL LiteHDSLIDSLRADSLSDSLUDSLVDSLx2DSL1 概述 xDSL是DSLDigital Subscriber Line的统称即数字用户线路是以铜电话线为传输介质的点对点传输技术DSL技术在传统的电话网络

38、POTS的用户环路上支持对称和非对称传输模式解决了经常发生在网络服务供应商和最终用户间的最后一公里的传输瓶颈问题由于电话用户环路已经被大量铺设因此充分利用现有的铜缆资源通过铜质双绞线实现高速接入就成为运营商成本最小最现实的宽带接入网解决方案DSL技术目前已经得到大量应用是非常成熟的接入技术 xDSL系统主要由局端设备DSLAMDigital Subscriber Line Access Multiplexer和用户端设备CPE组成 局端由DSLAM接入平台DSL局端卡语音分离器IPC数据汇聚设备等组成如图所示语音分离器将线路上的音频信号和高频数字调制信号分离并将音频信号送入电话交换机高频数字调

39、制信号送入DSL接入系统DSLAM接入平台可以同时插入不同的DSL接入卡和网管卡等局端卡将线路上的信号调制为数字信号并提供数据传输接口IPC为DSL接入系统提供不同的广域网接口如ATM帧中继T1E1等这些设备都设在电话系统的交换机房中用户设备由DSL Modem和语音分离器组成DSL Modem对用户的数据包进行调制和解调并提供数据传输接口 2 DSL调制技术 DSL技术是利用在电话系统中没有被利用的高频信号传输数据DSL利用了更加先进的调制技术目前被广泛采用的ADSL调制技术有3种QAMquadature ampli-tude modulationCAPcarrierless amplitu

40、de-phase modulation DMTdiscrete multitone其中DMT调制技术被ANSI标准化小组T1E14制订的国家标准所采用但由于此项标准推出时间不长目前仍有相当数量的ADSL产品采用QAM或CAP调制技术 QAM调制技术的实现方法如下发送数据在比特符号编码器内被分成两路速率各为原来的12分别与一对正交调制分量相乘求和后输出与其它调制技术相比QAM编码具有能充分利用带宽抗噪声能力强等优点QAM 用于ADSL的主要问题是如何适应不同电话线路之间性能较大的差异性要取得较为理想的工作特性QAM接收器需要一个和发送端具有相同的频谱和相位特性的输入信号用于解码QAM接收器利用自

41、适应均衡器来补偿传输过程中信号产生的失真因此采用QAM的ADSL系统的复杂性主要来自于它的自适应均衡器 CAP调制技术是以QAM调制技术为基础发展而来的可以说它是QAM技术的一个变种输入数据被送入编码器在编码器内m位输入比特被映射为k2m个不同的复数符号Ananjbn由K个不同的复数符号构成k-CAP线路编码编码后an和bn被分别送入同相和正交数字整形滤波器求和后送入DA转换器最后经低通滤波器信号发送出去CAP技术用于ADSL的主要技术难点是要克服近端串音对信号的干扰一般可通过使用近端串音抵消器或近端串音均衡器来解决这一问题 DMT调制技术的主要原理是将频带0-1104MHZ分割为256个由频

42、率指示的正交子信道每个子信道占用4KHZ带宽输入信号经过比特分配和缓存将输入数据划分为比特块经TCM编码后再进行512点离散傅利叶反变换IDFT将信号变换到时域这时比特块将转换成256个QAM子字符随后对每个比特块加上循环前缀用于消除码间干扰经数据模变换DA和发送滤波器将信号送上信道在接收端则按相反的次序进行接收解码 3 DSL分类 DSL技术主要分为对称和非对称两大类 xDSL中 x代表着不同种类的数字用户线路技术各种数字用户线路技术的不同之处主要表现在信号的传输速率和距离还有对称和非对称的区别上31 对称DSL技术 对称DSL技术主要有以下几种 1HDSL高比特率DSL HDSL是xDSL技术中最成熟的一种已经得到了较为广泛的应用这种技术可以通过现有的铜双绞线以全双工T1或E1方式传输其特点是利用两对双绞线传输支持N×64kbps各种速率最高可达E1速率HDSL是T1E1的一种替代技术主要用于数字交换机的连接高带宽视频会议远程教学