题目内容
（请给出正确答案）
A.Omni-directional base station
B. Base station with 3 cells, horizontal 65 degree, about 15.5dbi gain
C. Base station with 3 cells, horizontal 65 degree, about 18dbi gain
D. Base station with 3 cells, horizontal 90 degree, about 15.5dbi gain
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更多“The base station and antenna s…”相关的问题
The double-blind laboratory tests means （）.
A.nobody taking part in the test knows if the 3G base station is transmitting signals
B.only the subjects in the test know if the 3G base station is transmitting signals
C.no researchers know if the 3G base station is transmitting signals
D.everyone in the test knows if the 3G base station is transmitting signals
A. Larger than
B.Lower than
C.Equal to
D.Not comparable with
A. 1 parameter
B. C2 parameter
C. Level value Rxlev
D. Base Station Identity Code (BSIC)
A.Map;
B. Subscriber complaints
C. Test
D. Frequency
E. Base station cell
A.无线系统
B.无线频率功率放大器
C.所有的数字信号处理设备
D.小区结构数据
requency re.use in the network)？()
A.It increases the sensitivity of the mobile
B.It increases the number of mobiles with high C/I
C.The power consumption in the radio base station is reduced
D.It reduces the risk of MS receiver saturation
E.It reduces the number of mobiles with low C/I
cancer. originally,because of a lawsuit that alleged such a link Network news programs ran their own tests of cell phones,reporting to the public that some cell phones exceed the maximum level of emitted radio frequency energy allowed by the US Federal Communications Commission.
In 2000.it was estimated that there were 92 million cell phone users in the United States and this number was growing by 1 million every month. More recently,the Cellar Telecommunications & Internet Association estimated that there were almost 170 million US cell phone users, and the seriousness of brain tumours, this is clearly a topic of wide concern.This report summarizes what we now know about the carcinogenicity of using cell phones.
Cell phones operate with radio frequencies.a form. of energy located on the electromagnetic spectrum between F M radio waves and the waves used in microwave ovens,radar;and satellite stations.Cell phones do not emit ionizing radiation,the type that damages DNA and is known to have the ability to cause cancer.
Cell phone technology works on a system of geographically separated zones called "cells" Each cell has its own "base station" that both receives and emits radio waves.When a call is placed from a cell phone,a signal is sent from the cell phone antenna to that cell's base station antenna.The base station responds to the cell phone signal by assigning the phone an available RF channel.When the RF channel is assigned,radio signals are simultaneously received and transmitted, allowing voice information to be carried between the cell phone and the base.The base station transfers the call to a switching centre.where the call can be transferred to a local telephone carrier or another cell phone.
6.There has existed argument about the link between cell phone and brain tumour.()
7.The rapid growing number of cell phone users has been a great concern in the US.()
8.The 3rd paragraph tries to prove that cell phones do not cause brain cancer.()
9.A switching centre is needed when we make a call through cell phone.()
10.The topic of the passage is about cell phone and cancer.()
Denny
His nickname is Denny. He weighs 400 pounds; he is fearless and he never goes to sleep on the job. An ideal security guard？ For many situations he may be. And if he's so good that you wish you had a dozen like him, just place your order. Denny is a robot guard.
Denny can detect, within a 150-foot radius, the presence of anything or anybody that shouldn't be there. Its swiveling (旋转) head contains microwave and infrared sensors that can detect people as well as smoke. In future editions the head will also contain sensors that can smell the weak smell of a human body.
A high-resolution TV camera in Denny's head is on at all time. When something Unexpected comes into view; the TV transmitter switches on. Thus the human overseer (看管人) in the control center sees the sudden appearance of a picture on the monitor screen. At the same time the picture is automatically videotaped.
Normal speed of the robot guards is about one mile an hour, and. they can even talk: 'you have been detected,' warns the voice from the clever guard. Denny is designed to patrol corridors and other areas after lock-down hours (of course, he can work round the clock when necessary), not to move among people. If, say, a prisoner does get near the corridor where he should not be, it'll immediately tell its base station by radio.
Denny has understandable limitations. He can't open doors or watch stairs, for example, or distinguish friend from enemy. Thus he will have to go about unarmed. And he won't be able to replace human security guards where people move about freely.
Denny is a robot guard, who
A．has mechanical anus and legs.
B．has microwave and infrared sensors.
C．has a built-in computer.
D．depends on his built-in radio for distinguishing a friend from an enemy.
