Questions 5-11Choose NO MORE THAN THREE WORDS from the passage to fill the blanks in the following questions.
The Flying Phone Box
1. The strides made in satellite-communications technology in recent years are at last yielding benefits for air travellers, particularly executives who need to keep in touch with their offices. Five airlines — three of them based in the Asia-Pacific region — have recently equipped aircraft to offer outbound telephone calls to anywhere in the world using a new satellite system. And in the not-too-distant future, businessmen will be able to send faxes in flight, too.
2. Air Canada, Qantas of Australia, United Airlines of the US and Japan Airlines have at least one satellite-communication aircraft apiece. Hong Kong's Cathay Pacific Airways is also about to offer the service and several other airlines are expected to follow. The calls, dialled directly and charged to a credit card, will cost about US $9-10 per minute.
3. Phone communications from aircraft are not entirely new. For some time, telephones have been available to passengers on US internal flights, for example, and on private jets.
4. But these systems have used cellular phones operating on very high frequency (and also high frequency) radio links. These systems — the same links that keep pilots in touch with flight controllers — have either limited range or low quality and reliability, particularly over vast oceans such as the Pacific. By contrast, the new satellite service will provide clear links instantly to destinations around the world.
5. Several technological problems had to be resolved before the service could be introduced. One was to define an effective technical standard, Airinc 741, that guarantees compatibility among different manufacturers’ avionics systems — essential if the service was to be truly global.
6. Another was to make reliable antennas small enough and light enough to mount on aircraft of different types. And a third was to perfect voice-coding algorithms, which tell machinery how to break down voice signals into digital signals for transmission at the standard rate of 9,600 bits a second.
7. A further drawback, for any type of call routed by satellite, is an uncomfortable time lag between words being spoken and received. Because of the distance that signals have to travel, there is a delay of about a quarter of a second. With airborne calls, there is the potential for a double delay as signals arriving via satellite at a ground station are passed on via another satellite to their destination.
8. To avoid this problem, ground stations have been equipped to identify calls from aircraft and route them to coaxial or fibre-optic cables for the second leg of their journey. Surface links, though long, are still considerably shorter than the 72,000-km round-trip into space. Most calls will, therefore, not suffer the double delay.
9. The International Maritime Satellite Organization (Inmarsat) approved the initial satcom system for commercial service last November, after two years of trials. Besides the handful of aircraft operated by the five major carriers who have signed on to the system, about two dozen company jets have fitted with the necessary equipment.
10. The technology has three components: antennas and associated equipment on board planes, communications satellites, and ground stations.
11. In the course of development, antennas have lost both their dish shape and several kilograms. Even so, antenna and avionics weigh as much as two occupied seats. One obstacle to further weight savings, however, is that lighter antennas are more easily confused by the plethora of satellites now circling the Earth.
12. The satellites themselves are provided by Inmarsat, a London-based cooperative of 64 nations. One operational satellite and several back-ups cover each of three zones — the Atlantic Ocean (East), the Pacific, and the Indian Ocean. A fourth zone, Atlantic Ocean (West), will go into action later this year.
13. Three consortiums are competing for airlines’ business by setting up ground stations to accept calls bounced off Inmarsat satellites and channel them into telephone networks.
14. Skyphone, comprising British Telecom International, Norwegian Telecom and Singapore Telecom, has worldwide coverage through stations at Goonhilly, England; Eik, Norway; and Singapore. US satellite corporation Comsat has joined up with Japan’s international operator, KDD, with ground stations in Yamaguchi, Japan, and Southbury and Santa Paula, on the US East and West Coasts.
15. In addition, the Social Internationale de Telecommunications Aeronautique, a cooperative owned by airlines, has combined with Teleglobe. Canada, France Telecom and OTC of Australia to create Satellite Aircom, with ground stations in Perth, Australia; Aussaguel, France; Weir, Canada; and Niles Canyon, US.
16. According to Hans Karisen, Inmarsat's marketing manager for aeronautical services, the prospects for aircraft-satellite communications look particularly bright in the booming Asia-Pacific air travel market. Around the region, aircraft are flying full and carriers are better able to afford the roughly US $500,000 cost of equipping each airliner. But many carriers will order the equipment only for new aircraft rather than take existing ones out of service for lengthy modifications.
17. Satellite communications will also help improve flight efficiency. A system of voice and data links is already operating between aircraft and their operations centres which, for example, enables crews to obtain permission to change altitudes at the optimum time for fuel efficiency.
18. Crews can also call ahead for maintenance; an aircraft with a vibrating engine, for example, can be met on arrival by engineers who have already obtained computerized data on its behaviour. These communications, however, like most existing airborne telephones, mostly use radio links; in the future they, too, will be transferred to the satellite system.
19. The instant nature of the air-to-ground communication will also improve navigation, by allowing continuous reporting of aircraft positions. Indeed, a study by the International Civil Aviation Organization indicates that the technology could provide benefits worth between US $5-6 billion annually in fuel efficiency, faster repair turn-arounds and improved traffic flows through airports.
20. For the fidgety executive, meanwhile, air travel need no longer means a communications black-out. And some airlines are already developing data terminals that will permit passengers to change hotel and car-hire reservations, or contact their banks and brokers.
Which paragraph mentions problem C?
Which paragraph mentions problem A?
Which paragraph indicates it is difficult to solve problem B?
Which paragraph mentions how to solve problem D?
Apart from for passengers’ use, satellite communication on aircraft can also be used to , , call ahead for maintenance, and .
Aircraft crews keep in touch with control towers by using .
If double delay has to be prevented, have to be used.
Which area is not covered by a satellite yet?
How much docs it cost to install satellite telephone equipment onto one aircraft?