问题 问答题 简答题

什么叫同频道干扰?它在无线电负荷控制系统中有何影响?

答案

参考答案:凡是其他信号源发送出来与有用信号的频率相同,并以同样的方式进入中频通带的干扰,都称为同频道干扰;由于同频道干扰信号与有用信号同样被放大及检波,因而其结果会由于两个电台的载频差而造成差拍干扰,或者由于两个电台的调制度不同而引起失真干扰,或者由于有用信号与干扰信号的相位差而引起失真干扰,或者调制度虽然相同,但由于载频差、调制信号的相位差以及信号大小不同等因素的共同影响而造成干扰。干扰信号越大,接收机输出的信噪比越小。

单项选择题
单项选择题

Millions of Americans and foreigners see GI.Joe as a mindless war toy, the symbol of American military adventurism, but that’ s not how it used to be. To the men and women who (1) in World War I1 and the people they liberated, the GI. was the (2) man grown into hero, the pool farm kid torn away from his home, the guy who (3) all the burdens of battle, who slept in cold foxholes, who went without the (4) of 1hod and shelter, who stuck it out and drove back the Nazi reign of murder. This was not a vohmteer soldier, not someone well paid, (5) an average guy, up (6) the best trained, best equipped, fiercest, most brutal enemies seen in centuries.

His name is not much. GI. is just a military abbreviation (7) Govermnent Issue, and it was on all of the article (8) to soldiers. And Joe A common name for a guy who never (9) it to the top. Joe Blow, Joe Magrae... a working class name.The United States has (10) had a president or vieepresident or secretary of state Joe.

GI. Joe had a (11) career fighting Geman, Japanese, and Korean troops. He appears as a character, or a (12) of American personalities, in the 1945 movie The Story of GL Joe, based on the last days of war correspondent Ernie Pyle. Some of the soldiers Pyle (13) portrayde themselves in the fihn. Pyle was famous for covering the (14) side of the warl, writing about the dirt-snow-and-mud soldiers, not how many miles were (15) or what towns were captured or liberated. His reports (16) the "willie" cartoons of famed Stars and Stripes artist Bill Maulden. Both men (17) the dirt and exhaustion of war, the (18) of civilization that the soldiers shared with each other and the civilians: coffee, tobacco, whiskey, shelter, sleep. (19) Egypt, France, and a dozen more countries, G. I. Joe was any American soldier, (20) the most important person in their lives.

18()

A.stages

B.illusions

C.fragments

D.advances