Objectively speaking, ADSL is one of the easiest broadband technologies to implement because it is built on telephone lines, and the domestic telecom sector has the richest resources of copper wires, which is ranked second in the world after the United States. It is also because of this factor that ADSL is being heavily promoted across the country.
Technically, ADSL divides the user spectrum over a twisted pair into three bands. Because of this asymmetry of low uplink rates and high downlink rates, ADSL is called Asymmetrical Digital Subscriber Line (Asymmetrical DSL) technology. In fact, this is very suitable for users to browse the web, VOD and other high bandwidth download data applications.
Performance Analysis
1, fast speed
ADSL supports commonly used downlink rates up to 8Mbps, 150 times the speed of a Modem, and uplinks up to 640kbps.
2, the Internet does not need to pay the phone bill
ADSL transmits data and voice signals separately on the same copper wire, and the data signals do not pass through the telephone exchange equipment. The data signal does not pass through the telephone exchange equipment and does not require dialing, which means that you don't need to pay the telephone bill to use ADSL to access the Internet. In many areas, ADSL is basically paid for on a monthly basis at a fixed cost and there are no restrictions on its use. In addition, because it is a dedicated line to the Internet, can be with the ordinary phone **** stored in a telephone line, so the Internet and answer the phone, make a phone call does not affect each other.
3, can realize a variety of services
ADSL's effective transmission distance of 3 to 5 kilometers, it can also be based on the quality of twisted copper wire quality and transmission distance dynamically adjust the user's access to the speed, you can meet the requirements of the full-screen moving images of multimedia applications, such as obtaining a 1.5Mbps (MpEG-1) bandwidth, equivalent to the VCD image For example, it can get 1.5Mbps (MpEG-1) bandwidth, which is equivalent to VCD image quality, or even 3Mbps~6Mbps (MpEG-2 bandwidth), which is equivalent to DVD image quality, which is far from being satisfied by the traditional transmission method. Since ADSL is much faster than Modem dial-up, it makes ADSL an ideal technology for high-speed surfing on the Internet, video-on-demand, and remote local area network access.
Although ADSL has a lot of advantages, but there are also its own shortcomings, such as higher requirements for telecommunications technology, higher quality requirements for telephone lines, higher production costs, the initial installation fee and the use of higher fees, and each user occupies a dedicated line bandwidth so that the limited resources can not be fully utilized, as well as the existence of the quality of the telephone line and the disadvantages of the loss of information over long distances, and so on.
Costs
For ADSL users, the costs mainly include: hardware equipment (i.e., the cost of ADSL Modem, NICs and splitters), the initial setup fee, and monthly usage fees. The specific tariffs for each city in China vary slightly depending on their promotional policies, but the cost components are basically similar.
Taking Shanghai as an example, the current terminal equipment fee provided by Shanghai Telecom is 790 yuan, the equipment installation and debugging fee is 400 yuan, plus a 10 yuan handling fee, the cost of the initial investment in about 1,200 yuan. After the "down payment", you only need to pay another 130 RMB per month (including 50 RMB monthly fee and 80 RMB monthly information fee) to enjoy unlimited bandwidth of 512kbps on the Internet.
At present, telecommunication bureaus around the world generally require the purchase of the ADSL Modem terminal equipment they provide when installing ADSL for users. ADSL Modem can be divided into three types: built-in, external and USb. The specific choice of which type, you can according to their own needs, which external ADSL Modem installation, setup and use is more convenient, but more expensive, and because the external ADSL Modem (Figure 2) uses an Ethernet interface, so you need to be connected to the computer with an Ethernet card. The ADSL Modem with built-in pCI interface is cheap, generally the mainstream 400~500 RMB can be taken, and it does not occupy external space, which is very economical for general home users. Of course, you can also give due consideration to the USb ADSL Modem, which features easy installation and use, hot-swappable support, and faster interface speeds.
Applicable People
Through the above introduction, we can have a clearer understanding of the features, functions and current tariffs of ADSL. As we can imagine, the main issue that ultimately affects your choice of Internet access is undoubtedly your own needs, objectives, and the cost-effectiveness of the corresponding access method.
At this stage, in addition to Modem dial-up as a low-end popularized access method, ADSL technology is undoubtedly the main access technology for telecom companies to occupy the broadband access network market. Therefore, from a practical point of view, at present, for home users as well as some small businesses, the most practical and most cost-effective access method is feared to be ADSL. Of course, as time goes by, ADSL will replace Modem dial-up as a necessity.
Due to the rapid expansion of the number of Internet users in China, the slow speed of the network and the expensive charges have become two major obstacles to the development of China's Internet. ADSL has developed rapidly because it has not been "aristocratic" because of its advanced nature, but rather positioned as a "popular" high-speed access to the Internet. The reason why ADSL has developed rapidly is that it has not been "aristocratized" because of its sophistication, but has been positioned as a "popular" high-speed access service. As the two most important factors to be concerned about the Internet - performance and price, ADSL has a good performance: 512kbps bandwidth is much faster than our mainstream Modem; due to the implementation of the monthly subscription system, more than 100 yuan of network costs are also relatively inexpensive. In the current ADSL users, individual users and business users accounted for half, it shows that ADSL has stepped into the small company, home users, and the cost is also affordable to ordinary users. So, if you are more frequent Internet access, Internet time is longer, you need to often carry out the transmission of large amounts of data or want to watch Internet movies, listen to Internet radio, and the local can provide ADSL broadband access, you still early on installed ADSL it!