【名词&注释】
变频器(inverter)、调制器(modulator)、工程验收(acceptance of work)、可视电话系统(video phone system)、光纤通信系统、数字传输(digital transmission)、微波通信系统(microwave communication system)、交叉调制(cross modulation)、告警信号(guard signal)、外部设备(peripheral equipment)
[单选题]《通信电源集中监控系统工程验收规范》规定：系统应进行同时多点告警信号(guard signal)测试，选取告警信号(guard signal)数量应不少于总告警信号(guard signal)数量的( )。
A. 10%
B. 20%
C. 30%
D. 40%
查看答案&解析
举一反三：
[单选题]下列选项中，将外部设备(peripheral equipment)和主机相连在一起的是（ ）。
A. 总线
B. 控制器
C. I/O 接口
D. ALU
[多选题]数字化就是在通信网上全面使用数字技术，包括（ ）。
A. 数字传输
B. 数字交换
C. 数字终端
D. 数字业务
[单选题]可视电话系统丰富了通信的形式和内容，满足了人们对通信的更多追求，其组成的核心部分是（）。
A. 语音处理分部
B. 图像信号输入部分
C. 图像信号输出部分
D. 图像信号处理部分
[单选题]将波长间隔在（）的复用称之为密集波分复用（DWDM）。
A. 零点零零几纳米
B. 零点零几纳米
C. 零点几纳米
D. 零点几纳米
[单选题]微波通信系统(microwave communication system)中发信机中的（ ）用于把发送的射频信号提高到足够的电平，以满足经信道传输后的接收场强。
A. 调制器
B. 上变频器
C. 高功率放大器
D. 天线
[多选题]速率匹配要完成的工作有哪些().
A. 速率匹配参数的确定
B. 速率匹配方案
C. 比特分离和合并
D. 速率匹配算法
[多选题]微波通信系统(microwave communication system)中发信机由（）组成。
A. 调制器
B. 上变频器
C. 高功率放大器
D. 天线
[多选题]4G is one of those terms that keep coming back through marketing brochures for what the latest technologies happen to be in the cellphone market. Every carrier claims to have true 4G, and has been claiming that for years, regardless of what they actually use. The reason was simple because the real 4G specification, expected to be drafted by the International Telecommunication Union, was no where to be found. In fact, the ITU took way longer than being expected to come up with a decision, likely because of massive lobbying campaigns. After all, which company wants to have to redesign its entire network just to be able to keep saying they are 4G? Now however, they ITU has decided itself.What does this mean for carriers and users? First，let’s see what 4G really is. As expected, LTE is central to the ITU strategy,but more precisely,the organization went with LTE-Advanced,which is a stricter version of traditional LTE. To qualify as 4G，a network has to provide 100Mbps connections over wireless,and 1 Gbps over wired. The whole network has to be fully IPv6 compliant. Frequencies have to be variable over 40MHz to avoid interference. Finally, global roaming has to be seamless, along with transitions between wirless and wired connections. This is a real step forward, and a good decision, which ensures that real 4G services will meet a good level of services. Technically, LTE-Advanced is just one of two new standard that are now under the umbrella called IMT-Advanced. The other one is WiMAX 2 which is a further refinement of the WimMAX protocol. Based on the paragraph above，to qualify as 4G, a network has to satisfy （） criteria. The transitions between wireless and wired connections have to be （）. LTE-Advanced is a standard belonging to （）.
A. two
B. three
C. four
D. five A．limited
E. possible
F. seamless
G. deployed A．WiMAX
H. WiMAX 2
I. IPv6
J. IMT-Advanced
[多选题]目前广泛使用的光纤通信系统均为强度调制——直接检波系统，对光源进行强度调制的方法有（）。
A. 直接调制
B. 间接调制
C. 交叉调制(cross modulation)
D. 混合调制
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