modem communication system meaning in English

调制解调制通信系统

Speech communication is very important and indispensable service in different modem communication systems
在现代各种通信系统中，语音通信一直是一项非常重要的、必不可少的业务。
The design about power amplifiers is much a challengeable topic , especially in the more complicated performance of modem communication systems . it is very significant making a thorough and careful study on the design of the power amplifier
其设计是一个极富挑战的研究课题，特别在通信系统功能越来越复杂的今天，对它进行深入细致的研究非常有意义。