Digitalif Design And Implementation With Coaxial Broad Band Access Signal

In the context of triple network playing,communication carriers are constructinglarge-scale FTTH network which has the advantages of high network bandwidth,highreliability and good qualityof signal transmission.The participant of triple networkplaying—radio and television operators face intense pressure on access networktransformation from communication carriers.However,FTTH network is expensive and lower cost,moreover, radio and televisionoperators on the development of coaxial access network are still not fully.So, radio andtelevision operators should raise the next generation access network solution which isbased on the existing coaxial access network,but also provides users with greater accessbandwidth services.Therefore, the scheme of broadband access signal digital IF design based on coaxialaccess network is proposed.Software Defined Radio is combinated with coaxial accessnetwork in the scheme,and the program provides the solution for wideband signaldigital IF processing.First,three platform structures of SDR are analyzed in the paper,and the RF low-passsampling digital structure is adopted, which complies with the requirement of SDR andhas the best flexibility and scalability. In the same time, the article details the softwareradio digital IF key technology status, and combines with the needs analysis todetermine the key parameters of the system.Secondly,digital IF system is divided into three parts of the functional modules,interface modulesand global module in the paper, and this paper presents a detaileddesign of each module in the system.Decimation filter and interpolation filter adoptpolyphase filter structure, and the problem of across clock domains is solved by FIFO inthe system.Finally,the paper complete functional test of ADinterface,DA interfaces,BBboardinterface,SPI interface,and functional and performance test of the entire system.From the test results,the high-speed interface modules function properly, data rates ofAD interface, DA interface and BB board interface are respectively3072Mbps,1536Mbps,6.14Gbps.Functional test of the entire system is normal, the systemcomplete DDC and DUC function by96M bandwidth signal, and its EVM is0.4623%.This paper completes the scheme of broadband access signal digital IF design basedon coaxial access network.By testing the entire system, the results verify the feasibilityof the scheme.This scheme combines with digital baseband solution to accomplish4096QAM modulation.This paper provides a reliable theory and implementationbasison the applications of SDR technology in the coaxial access network.