通信电路的设计

通信电路的设计:

According to UNESCO statistics, in 1997, there were 2.4 billion radio receivers in
nearly 200 countries. The figure for television was 1.4 billion receivers. During the same year, it was reported that there were 822 million main telephone lines in use world-wide. The number of host computers on the Internet was estimated to be 16.3 million [1]. In addition to this, the military in every country has its own communication network which is usually much more technically sophisticated than the civilian network. These numbers look very impressive when one recalls that
electrical telecommunication is barely 150 years old. One can well imagine the
number of people employed in the design, manufacture, maintenance and operation
of this vast telecommunication system.