问题 问答题 案例分析题

在使用EDFA+DRA结合的跨段中,需要配置APR保护,如下图所示:

如需要实现APR组功能,还需要增加什么单板才能完成?解释一下原因。并给出新增单板在图中的准确位置。增加OPM单板。

答案

参考答案:

由于DRA是分布式放大器,其放大区域为线路光纤,因此无法按以往的监测器检测方案实现APR功能-DRA本身造成的光噪声导致R端设备无法检测线路是否中断。DRA单板自身无法检测信号是否中断,因此在具备DRA的站点增配OPM来完成对信号的监测。

接在收端的OPA或OLA的MON口上。

阅读理解

Washington, April 4----- The United States has more than 90 million families for the first time, but each contains fewer people on average than ever, the Census Bureau(统计局) reported today.

The 90,031,000 families in the United States averaged 2.64 members each as of last July 1.“The reason is, in effect, changes in the age structure,” explained Campbell Gibson, a population researcher for the bureau. Most Americans born in the great explosion of births are now in their 20’s and 30’s when they most likely to set up families, he said.

The fact that many are doing so increased the number of families from 80.4 million in 1980 t0 88.8 million in 1986 and past the 90 million mark last summer.

At the same time, the average number of people per family dropped from 2.75 in 1985 to 2.65 in 1986 and then to 2.64, Mr Gibson said.

By comparison, the 1970 Census found the average family contained 3.14 people. Families averaged more than four people in 1939 and more than five in 1880.

The growing number of ever---- smaller families is still going on, but Mr Gibson pointed out that family growth was not the same as population increase in the 1970’s.

The same age factors that are increasing the number of families also happened then, but in the 1970’s the proportion(比例) of families in each age group was also growing.

That hasn’t continued in the 1980’s for a number of possible reasons, Mr Gibson said. For example, in the 1980’s more young people have chosen to remain home with their parents instead of setting up housekeeping on their own, as many did in the 1970’s.

This could be caused by the increasing cost of housing, he said. Delays in marriage while young people go to work and school, have also been widely reported as a factor, but it was not the only factor for the family changes.

小题1:The smaller figure of families reported here is _________.

A.1980

B.80,400,000

C.2.64

D.90 million小题2:What’s the reporter’s attitude towards the present situation?

A. People should get married at later age.

  1. The average number of family members should be 2.64.
  2. It’s not clear in the report.
  3. Young people should set up housekeeping on their own, as many did in the 1970’s.
小题3:From the last paragraph we may infer that________.

A. delay in marriage will not help the number of the families

  1. delay in marriage is the major factor of the family changes
  2. the writer felt sorry that many young people now delay their marriages
  3. there must be some other factors which have led to the slower growth in the 1980’s
小题4: The underlined word “factor” in the passage means_________.

A.reason

B.something that proves be true

C.advantage

D.something that helps to bring about a result

填空题