搜题请搜索小程序“爱下问搜题”
问题 填空题

奈奎斯特(Nyquist)准则与香农(Shannon)定理从定量的角度描述了 【7】 与速率的关系。

答案

参考答案：带宽

解析： 本题考查点是奈奎斯特准则与香农定理。奈奎斯特(Nyquist)准则与香农 (Shannon)定理从定量的角度描述了信道带宽与数据传输速率之间的关系。奈奎斯特定理推导出对于一个理想的无噪声干扰的低通信道，其最大数据率为：
Rmax=2W(Baud) ＝2Wlog2N(bps)
香农公式表述有随机噪声干扰的信道的最大数据传输率为：
Rmax=Wlog2(1+S/N)(bps)

单项选择题

A transport layer protocol usually has several responsibilities．One is to create a process-to-process communication；UDP uses (1) numbers to accomplish this．Another responsibility is to provide control mechanisms at the transport level．UDP does this task at a very minimal level．There is no flow control mechanism and there is no(2) for received packet．UDP, however, does provide error control to some extent．If UDP detects an error in the received packet，it will silently drop it． The transport layer also provides a connection mechanism for the processes．The (3) must be able to send streams of data to the transport layer．It is the responsibility of the transport layer at (4) station to make the connection with the receiver, chop the stream into transportable units，number them，and send them one by one．It is the responsibility of the transport layer at the receiving end to wait until all the different units belonging to the same process have arrived，check and pass those that are (5) free, and deliver them to the receiving process as a stream．

（3）处应填（）。

A．jobs

B．processes

C．programs

D．users
查看答案
单项选择题

下列二次型中属于正定二次型的是
(A) f(x1，x2，x3，x4)=(x1-x2)2+(x2-x3)2+(x3-x4)2+(x4-x1)2．
(B) f2(x1，x2，x3，x4)=(x1+x2)2+(x2+x3)2+(x3+x4)2+(x4+x1)2．
(C) f3(x1，x2，x3，x4)=(x1-x2)2+(x2+x3)2+(x3-x4)2+(x4+x1)2．
(D) f4(x1，x2，x3，x4)=(x1-x2)2+(x2+x3)2+(x3+x4)2+(x4+x1)2．
查看答案