通信系统中，称调制前的电信号为（）信号，调制后的电信号为（）信号。

通信系统中，称调制前的电信号为（）信号，调制后的信号为调制信号。

Every deliberate act of wrongdoing by the master or any of the crew against the ship or cargo，without the authorization or privity of the Shipowner or his agent，is（）.

（）, or drum is used for hauling in or letting out the wires or ropes which will fasten the ship to the shore.

A salvor may be（）the whole or part of the payment due under Salvage Convention to the extent that the salvage operations have become necessary or more difficult because of fault or neglect on his part or if the salvor has been guilty of fraud or other dishonest conduct.

The （） is used for hauling in or letting out the wires or ropes.

Vessels must be（）valid certificate of nationality or certificated of registry or license.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

扩频通信系统均要3次调制分别为信息调制、（）和（）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

通信系统根据是否采用调制，可分为基带传输系统和调制传输系统。

数据通信的频带传输中需要对数字信号进行载波调试，有幅度调制、频率调制和（）