根据下面的文字资料回答 71~75 题 In the following essay.each blank has four choices.Choose

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根据下面的文字资料回答 71~75 题 In the following essay.each blank has four choices.Choose the best answer and write down on the answer sheet.

Spread spectrum simply means that data is sent in( 1 )pieces over a number of the discrete frequencies available for use at any time in the specified range.Devices using( 2 ) spread spectrum(DSSS)communicate by splitting each( 3 )of data into several parts and sending them concurrently on different( 4 ),DSSS uses a lot of the available( 5 ),about 22 megahertz(MHz).

第71题:文中( 1 )处正确的答案是( )。

A.small

B.high

C.low

D.long

参考答案:

A简单地来说,扩频就是在一个可以随时使用的特定频率范围内,把数据用小块在大量不连续的频率上同时发送。使用直序扩频 图6网卡的简单框架的设备相互之间通信是通过把每个字节的数据分成几个部分在不同的频率上同时传送。直序扩频使用了大约22 Mb的有效带宽。

软考中级