文件名称：Digital Modulation
文件大小：34KB
文件格式：DOC
更新时间：2016-06-02 12:21:58
数字调制
Modern communication systems use digital modulation techniques. Advancements in very large integration (VLSI) and digital signal processing (DSP) technology have made digital modulation less cost than analog transmission systems. Digital modulation offers many advantages over analog modulation.Some advantages include greater noise immunity and robustness to channel impairments,easier multiplexing of various forms of information (e.g.,voice,data,and video),and greater security.Furthermore,digital transmission accommodate digital error-control codes that detect and/or correct transmission errors,and support complex signal conditioning and processing techniques such as source coding,encryption,and equalization to improve the performance of the overall communication link.New multipurpose programmable digital signal processors have made it possible to implement digital modulators and demodulators completely in software.Instead of having a particular modern design permanently frozen as hardware,embedded software implementations now allow alterations and improvements without having to redesign or replace the modem.