In detail, the author narrates the function and working elements of network card, and the signal processing from baseband to IF to RF, also the protocol process of medium access control (MAC) layer.

详细讲述了网卡的功能构成、工作原理、从射频到中频到基带的信号处理过程、以及媒体访问控制层(MAC)协议处理方法等。

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The elements of a telecommunication system are a transmitter, a medium (line) and possibly a channel imposed upon the medium (see baseband and broadband as well as multiplexing), and a receiver.

组成通信系统的基本要素包括发信机，通道以及收信机。

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