At the beginning , this paper has some brief dissertation on the basic principle of the dsl and the multimedia data compression , the key technique of sdsl , the transport protocols , and the data transfer system structure based on the twisted - pair . then it gives an analysis of the point - to - point data link protocol ( ppp ) and the real - time transmission protocol in detail , which provide the side - to - side transmission service for audio frequency and video frequency data , and so on based on the these , we developed a multimedia sdsl modem system used to transfer data and phonetic 本文首先對(duì)dsl系統(tǒng)和多媒體數(shù)據(jù)壓縮技術(shù)的基本原理、 sdsl的關(guān)鍵技術(shù)、傳輸協(xié)議以及基于雙絞線的數(shù)據(jù)傳輸系統(tǒng)的結(jié)構(gòu)進(jìn)行了簡要的論述,并詳細(xì)分析了點(diǎn)到點(diǎn)的數(shù)據(jù)鏈路協(xié)議( ppp協(xié)議)以及實(shí)時(shí)傳輸協(xié)議,其為音頻、視頻等實(shí)時(shí)數(shù)據(jù)提供端到端的傳送服務(wù)。可以向接收端傳送恢復(fù)實(shí)時(shí)信號(hào)必需的定時(shí)和順序信息,并向收發(fā)雙方和網(wǎng)絡(luò)運(yùn)營者提供qos監(jiān)測手段。