皮皮学，免费搜题
登录
搜题
【单选题】
已知一个565Mbit/s光纤传输系统，其系统总体要求如下： （1）光纤通信系统光纤损耗为0.1dB/km，有5个接头，平均每个接头损耗为0.2dB，光源的入纤功率为-3dBm，接收机灵敏度为-56dBm（BER=10-10）。 （2）光纤线路上的线路码型是5B6B，光纤的色散系数为2ps/（km•nm），光源光谱宽度1.8nm。注：设计中选取色散代价为1dB，光连接器损耗为1dB（发送和接收端个一个），光纤富余度为0.1dB/km，设备富余度为5.5dB。那么系统的中继距离：（ ）A.
217.5km
B.
47.12km
C.
170.38km
D.
264.62km
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】The story was about the passengers' experience on the train from St. Albans to Farringdon _______ Wednesday 9th December 2009.
A.
in
B.
on
C.
at
D.
with
【简答题】He was (patience) ______ waiting for his wife, because the train was about to leave.
【单选题】The train was about to leave and I was not even on the _______ .
A.
platform
B.
pedagogue
C.
involves
D.
group
【单选题】He said the train ________ at six the next morning. [ ]
A.
was leaving
B.
was about to leave
C.
should leave
D.
left
【单选题】The train was about to leave and I was not even on the ______.
A.
board
B.
terminal
C.
platform
D.
taste
相关题目：