【導(dǎo)讀】段，這是非常小的，約，它更適合長(zhǎng)距離大容量傳輸，是首選的長(zhǎng)途骨干傳輸介質(zhì)。目前，為了適應(yīng)不同的線路和局域網(wǎng)的發(fā)展要求，已經(jīng)。制定了一個(gè)非分散纖維，低色散斜率光纖，大有效面積光纖，水峰光纖等新型光纖。輸距離，但它仍然是階段理論。信中繼器可以以不同的速率傳輸光纖放大器，也可以發(fā)送特定波長(zhǎng)的光信號(hào)。技術(shù)的擴(kuò)大，他們都不必改變摻鉺放大器電路和設(shè)備。摻鉺放大器可作為光接收機(jī)前。置放大器，后置放大器的光發(fā)射機(jī)和放大器的補(bǔ)償光源裝置。不同的環(huán)境中企業(yè)和住宅客戶提供了多種寬帶接入解決方案。目前，接入系統(tǒng)的主流技術(shù)，ADSL. 的分組網(wǎng)絡(luò)，語(yǔ)音流量將傳送到PSTN，ISDN或其它分組網(wǎng)絡(luò)。感器和調(diào)制解調(diào)器進(jìn)一步的需要。上面有各種設(shè)備的連接，供SIOB技術(shù)已足夠的密度光學(xué)集成電路制造小模塊。MEMS是一個(gè)微小的固體機(jī)械元件，其大小通常小于1毫米。目前的數(shù)據(jù)網(wǎng)絡(luò)技術(shù)已足以保證提供運(yùn)動(dòng)圖像和其它高帶寬服務(wù)。戶對(duì)一對(duì)普通的用戶。

　　

【正文】 tleneck to solve this ring circuit provides a broad development prospects. As the copper local loop is still analog signal transmission, people are still using the narrow radio channels across the crowded radio spectrum. How to access the current bottleneck in largescale widening work of the world39。s existing 750 million access line to provide ultrawideband, is the focus of the current work technology, the bottleneck is relative, a pair of wire can support twoway conversation sufficient capacity, but the traditional copper wire can provide bandwidth, highperformance data work and the Inter is indeed some reluctance, and other data users not only want to talk through the video conference system and hope to see each other39。s virtual image, so traditional access technologies (access, access routing) for high performance requirements in order to break through the bottleneck of work access links. To increase the work bandwidth of the last paragraph in the distance, in a wide range of reach and satisfy the user in the home or small office munications requirements of the basic premise. The local loop bottleneck is provided by the lower bit rate today due, in fact, in addition to local loop bandwidth limitations, the current data work technology has been sufficient to ensure the provision of moving images, and other highbandwidth services. 3. Access Technology From the total consideration, access to technology can be divided into wired and wireless access technologies, access to two types, wired access technologies can be divided into copper and fiber access technology access technology types. copper access technology Copper access the main focus is to consider how the current munications work in the total transmission length of about 1 / 3 part of the user line. The current copper access technologies are: highspeed digital subscriber line (HDSL) technology, asymmetric digital subscriber line (ADSL) technology and high bitrate Digital Subscriber Line (VDSL) technology. HDSL system using 2B1Q line code type, use of echo cancellation, adaptive filtering, signal processing technology to solve a number of ordinary users in a pair of twoway 18 transmission of online information , two pairs of users of online transmission of information. HDSL has the advantage of full use of existing cables to achieve expansion, and can solve the small number of users to transmit and 2048 kbps 384kbps broadband signals. The disadvantage is that currently can not transmit information over 2048kbps, transmission distance is limited within 6 to 10 km. ADSL asymmetric key used to transmit interactive broadband services. And as HDSL, ADSL is also trying to improve the general subscriber line highfrequency transmission. The socalled asymmetric means that such systems upstream direction (from user terminals to send direction to the switch) and the downstream direction (from the switch to send the user terminal direction) rate of asymmetric information. The uplink direction can send 64kbps ~ 384kbps digital signal。 the downstream direction can send ~ 6Mbps graphic images and broadband signals. Transmission distance up to 3 km to 4 km. ADSL39。s main purpose is to provide video on demand (VOD) services. ADSL 6 Mbps bandwidth for each can transmit 2 sets of MPEGⅡ ~ 3 or 4 sets of MPEGI digital image signal. ADSL uses discrete multifrequency transmission coding and noncarrier amplitude modulation, phase modulation technique. From a technical point of view, it solves the switch to the user39。s interactive broadband asymmetric transmission method, before pletion of the fiber access work, if you need to develop familyondemand TV, home teleeducation, telemedicine and other video services, the use of ADSL to solve broadband users business needs scattered, just use the existing copper wire of the transmission capacity without the need for transformation of the existing subscriber loop. But the ADSL broadband service is only as an excessive approach. VDSL is the view of the current ADSL technology to provide images in the broadband business is very limited and the high cost of economic weakness developed. Ordinary analog telephone line without change, the image signal by the end of HDT image interfaces by the Board to give the remote feeder fiber, the rate for STM4 or higher, the image operations can be either carried by the ATM cell of the MPEG Ⅱ signal, it can be a pure MPEGⅡ information flow. In the remote, VDSL line card can read the first letter or packet header and the desired cell or packet copy to the downstream direction of the destination user twisted pair. Remote transceiver module with an ordinary telephone service coupler (actually for a different frequency diplexer, also known as ordinary telephone service splitter) is responsible for a variety of signals coupled into the existing twisted pair copper. 19 Optical Access Technology Communication of large capacity optical fiber munication with high quality, stable performance, antielectromagic interference, strong confidentiality and so on. It has been widely reflected trunk munications. In access works, optical access will also be a focus of development. At present there are a variety of fiber optic access methods, namely: laying fiber to the remote contacts。 laying fiber to the office。 laying fiber to the curb。 laying fiber to the user munity。 laying fiber to every home. The main mode of optical fiber access to the trunk system and the wiring system at the junction point optical work unit (ONU) divided by location. ONU here is equivalent to the current subscriber line in the transfer box. From a technical point of view, FTTR, FTTB, FTTC, FTTZ basic approach, there is no substantive difference. From the operational point of view, the current volume of business the most, the mos