<span lang="EN-US" style="font-size:10.5pt;mso-bidi-font-size:12.0pt;font-family: "Times New Roman","serif";mso-fareast-font-family:宋体;mso-ansi-language:EN-US; mso-fareast-language:ZH-CN;mso-bidi-language:AR-SA">Modem</span><span style="font-size:10.5pt;mso-bidi-font-size:12.0pt;font-family:宋体;mso-ascii-font-family: "Times New Roman";mso-hansi-font-family:"Times New Roman";mso-bidi-font-family: "Times New Roman";mso-ansi-language:EN-US;mso-fareast-language:ZH-CN; mso-bidi-language:AR-SA">的作用是实现数字信号与模拟信号的转换</span>"/>