ADSL technology introduces:
Asymmetrical road of digital user annulus (ADSL- - Asymmetric Digital Subscriber Loop) can be in existing cupreous double skeining thread, the rate of high speed be issued to lower levels that is as high as 8Mbit/s is offerred on common line namely, outclass ISDN rate; And go up rate has 1Mbit/s, transmission distance amounts to 3km----5km. Its advantage depends on can making full use of existing cupreous cable network (line network) , in circuit two end add outfit ADSL equipment to be able to offer tall broadband to serve for the user, because do not need new wiring, reduced cost, reduced the cost that the user gets online then.
The main technique characteristic of technology of ADSL modulation demodulation depends on: ADSL technology uses infrastructure of existing phone copper cash to be able to be all families and enterprise to provide all sorts of telegraphic services almost, the rate that permits an user to be controlled 100 times higher in order to compare newest today 56KModem carries data network or Internet and relevant service undertake seesaw pattern corresponds. In communication of this kind of seesaw pattern, the down link of ADSL can be offerred than going up the bandwidth with taller circuitry, go up and down namely bandwidth is unequal, and be in commonly 1:10 the left and right sides. If of circuit go up rate is 640Kbps, criterion down link transmits rate with respect to the high speed that has 6.4Mbps. This namely why does ADSL cry asymmetrical the reason of digital subscribers feeder. In the meantime, because ADSL uses frequency,cent answer uses a technology, can shed phone speech and data to be transmitted together, the user needs to add only install equipment of an ADSL client side, pass spreader (one's voice in speech and data segregator) as shunt-wound as the phone, can make a common line communicates at the same time and get online and each other noninterference. Accordingly, used ADSL to receive kind, be equal to changing original below communicating circumstance, added online special railway line of a high speed additionally. Visible, ADSL technology and dial online modulation technology has very big distinction.