简述基站选址时应注意遵循的原则？
参考答案：
1）充分考虑基站的有效覆盖范围，从而达到满足覆盖目标的要求；
2）在话务密度较高的区域设置基站时，应在满足覆盖的前提下，根据系统可用无线带宽及未来一年话务增长的趋势，使得其在一年内，只需增加基站的载频数量，而不对基站数量做较大调整就可满足容量需求；
3）充分利用现有基站和其它通信资源；新建的GSM1800基站，要首先考虑与GSM900基站共站；基站的选址要考虑现有的传输条件。
4）基站的选址要考虑将来的可扩展性，机房应具备适当的面积，以便于扩容和引入第三代通信系统；
5）应考虑其他系统的干扰因素，保证必要的空间隔离；
6）基站站址宜选在交通便利、供电可靠的地方；
7）基站不宜设在大功率无线电发射台、大功率电视发射台、大功率雷达站等附近；
8）不宜选择在易燃、易爆建筑物场所附近以及危房、即将拆迁房；不宜选择在生产过程中散发有害气体、多烟雾、粉尘、有害物质的工厂企业附近。
| Questions 84-90 are based on the following passage. Imagine a society in which cash no longer exists. Instead "cash" is electronic, as in bankcard systems. Currency and coin are abandoned. The immediate benefits would be profound and fundamental. Theft of cash would become impossible. Bank robberies and cash-register robberies would simply cease to occur. Attacks on shopkeepers, taxi drivers, and cashiers would all end. Purse snatchings would become a thing of the past. Urban streets would become safer. Retail shops in once-dangerous areas could operate in safety. Security costs and insurance rates would fall. Property values would rise. Neighborhoods would improve. Drug traffickers and their clients, burglars and receivers of stolen property, arsonists for hire, and bribe-takers would no longer have the advantage of using untraceable currency. Electronic "money" would leave incriminating wails of data, resulting in more arrests and convictions. These prosecutions, in turn, would inhibit further crimes. The impact of the monetary change on underground economies would be nearly as dramatic as the effect on crime. In the United States, the underground economy is estimated at between 10% and 28% of the gross national product. Internal Revenue Service (IRS) researches suggest that almost all hidden labor is paid in currency. In a society devoid of physical money, a change from cash to recorded electronic money would be accompanied by a flow of previously unpaid income-tax revenues running in the tens of billions of dollars. As a result, income-tax rates could be lowered and the national debt reduced. Cash has been the root of much social and economic evil. The emergence of electronic funds-transfer technology makes it possible to change the nature of money and to divorce it from evil. Eighty percent of Americans regularly use credit cards. The development of a federal system to handle the country’ s 300 billion annual cash transactions in the United States electronically is within reach. A national electronic-money system would operate as debit-card system. Each individual’s "money" would be held in his money-system account. A transaction would effect an instant transfer of "money" from his account to that of another account holder. The principal differences between a national electronic-money system and commercial bank-card systems would be: the money system would be federally operated; payment would constitute "legal tender"; system-account holders would be able to receive as well as pay out funds by use of their accounts; and funds would be transferable between private-account holders as well as between merchants and private-account holders. Only cash would be supplanted by electronic money. The use of checks, drafts, money orders, traveler’s checks, cashier’s checks, as well as letters of credit, acceptances, and other financial instruments would remain in regular use. Credit card and automatic-teller-machine systems (ATMs) would not necessarily change, although you could no longer obtain cash at ATMs. |
Which of the following statements is NOT true
A．When the electronic money is used, the state will be able to collect more tax.
B．All monetary systems should aim at making cash unobtainable.
C．When cash is unobtainable, the rate of crimes can be reduced.
D．A national commercial bank-card system should also be abolished.
