This paper discusses the principles and methods of digital data transmission. and gives a brief introduction of the digital data transmission system , DDN AND CHINADDN.是什么意思_This paper discusses the principles and methods of digital data transmission. and gives a brief introduction of the digital data transmission system , DDN AND CHINADDN.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句