Архитектура Аудит Военная наука Иностранные языки Медицина Металлургия Метрология
Образование Политология Производство Психология Стандартизация Технологии
Text A. The Global Positioning System (GPS)
The Global Positioning System (GPS) is a U.S.-owned utility that provides users with positioning, navigation, and timing (PNT) services. This system consists of three segments:
1) The space segment constellation consists of 24 satellites, that transmit one-way signals that give the current GPS satellite position and time. 24 Space Vehicles (SVs) are distributed equally among six circular orbital planes. The orbital planes are centered on the Earth, not rotating with respect to the distant stars. Orbiting at an altitude of approximately 20,200 kilometers; orbital radius of 26,600 km, each SV makes two complete orbits each sidereal day.
2) The control segment consists of worldwide monitor and control stations that maintain the satellites in their proper orbits through occasional command maneuvers, and adjust the satellite clocks. It tracks the GPS satellites, uploads updated navigational data, and maintains health and status of the satellite constellation.
3) The user segment consists of the GPS receiver equipment, which receives the signals from the GPS satellites and calculates the user's three-dimensional position and time. In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and a highly-stable clock. Receivers typically have between twelve and twenty channels.
GPS has become a widely used aid to navigation worldwide, and a useful tool for map- making, land surveying, commerce, and scientific uses. To meet the specific user requirements for PNT, a number of augmentations to the GPS are available. An augmentation is any system that aids GPS by providing accuracy, integrity, reliability, availability, or any other improvement that is not inherently part of GPS itself.
Nationwide Differential GPS System provides increased accuracy and integrity of the GPS to users on land and water. Modernization efforts include enhancing the performance and providing 10 to 15 centimeter accuracy throughout the coverage area. Over 50 countries around the world have implemented similar systems.
Wide Area Augmentation System provides aircraft navigation for all phases of flight.
Continuously Operating Reference Station archives and distributes GPS data for precision positioning and atmospheric modeling applications mainly throughpost-processing1.
Global Differential GPS supports the real-time positioning, timing, and orbit determination requirements of the U.S. National Aeronautics and Space Administration (NASA) science missions. The U.S. Policy underscores the importance that all global navigation satellite systems and their augmentations be compatible with the GPS.
In addition to longitude, latitude, and altitude, the Global Positioning System (GPS) provides a critical fourth dimension - time. Each GPS satellite contains multiple atomic clocks that contribute very precise time data to the GPS signals. GPS receivers decode these signals, effectively synchronizing each receiver to the atomic clocks. This enables users to determine the time to within 100 billionths of a second. Precise time is crucial to a variety of economic activities around the world. Communication systems, electrical power grids, scientific study of earthquakes and financial networks all rely on precision timing for synchronization and operational efficiency. Wireless telephone and data networks use GPS time to keep all of their base stations in perfect synchronization. Similarly, digital broadcast radio services use GPS time to ensure that the bits from all radio stations arrive at receiversin lockstep2 . Companies worldwide use GPS totime-stamp3 business transactions. Major investment banks use GPS to synchronize their network computers located around the world. Hollywood studios are incorporating GPS in their movieslates4, allowing for unparalleled control of audio and video data, as well as multi-camera sequencing.
It is estimated that delays fromcongestion5 on highways and streets throughout the world result in productivity losses in the hundreds of billions of dollars annually. GPS enables automatic vehicle location and in-vehicle navigation systems that are widely used throughout the world today. By combining GPS position technology with systems that can display geographic information a new dimension in surface transportation is realized. A geographic information system (GIS) stores, analyzes, and displays geographically referenced information. Today GIS enables effective strategies that can keep transit vehicles on schedule and inform passengers of precise arrival times. GPS is an essential element in the future of Intelligent Transportation Systems (ITS). Research is being conducted in the area of advanced driver assistance systems, which include road departure and lane change collision avoidance systems. These systems need to estimate the position of a vehicle relative to lane and road edge with an accuracy of 10 centimeters. With the continuous modernization of GPS, one can expect even more effective systems for crash prevention, distress alerts and position notification, electronic mapping, and in- vehicle navigation with audible instructions.
GPS receivers come in a variety of formats, from devices integrated into cars, phones, and watches, and many other devices.
1) 1post-processing - обработка данных (to perform mathematical and logical operations on data according to programmed instructions in order to obtain the required information).
2) 2in lockstep - зд. строго одновременно, букв. «шаг в ногу» (progressing at exactly the same speed and in the same direction as other people or things).
3) 3time-stamp - временная отметка (to assign an accurate time to a message, transaction, etc.) The database entry consists of the MAC address, the port that address was seen on, and a time- stamp to indicate when it was see.
4) 4slates - доска, которой хлопают перед очередным дублем (a pair of boards clapped together during film shooting in order to aid sound synchronization).
5) 5congestion - скопление (the state of being overcrowded, esp. with traffic or people).
4.8 Write out of text A phrases describing general uses of GPS.
4.9 Answer the questions:
1) What are the main segments of GPS?
2) What augmentation are supposed in GPS?
3) Is the GPS system popular?
4) How many satellites does navigation system comprise?
5) What augmentation serves the US NASA science mission?
6) Why is timing so important?
7) What is the precision of atomic clock?
8) How are navigation systems used on the roads?
9) What is GIS?
10) What is ITS?
4.10 Read the text again and decide whether these statements are true (+) or false (—), correct the false ones:
1) The GPS provides only positioning services.
2) The system consists of four segments.
3) A number of augmentations are available in over 60 countries.
4) Precise time is crucial for military purposes only.
5) GPS is used in making modern films.
6) The delays on the roads directly affect the economy.
7) In-vehicle navigation systems are not common yet.
8) GIS is used to keep transit vehicles on schedule.
9) GPS is an essential element of ITS.
10) ITS is able to estimate the position of a vehicle with an accuracy of 1 cm.
Language in use
4.11 Replace the italicized words with the equivalents from the box.
1.The planes are orbiting at aheight of approximately 20000 km.
2. Each orbital plane carries four spaceconveniences.
3. Each space vehicle makes two complete orbits eachstellar day.
4. A number ofenhancements to the GPS are available.
5. Each GPS satellite contains multiple atomic clocks that contribute veryexact time data to the GPS signals.
6. The control segmentsupports health and status of the satellite constellation.
7. GPS has become a widely used help to navigation worldwide.
8. Delays from congestion on highways result in productivity losses in the hundreds of billions of dollarsyearly.
4.12 Complete the sentences with the words as in the text.
1. GIS is used to monitor_________________ location.
2. GIS stores, analyses and______________ geographically referenced information.
3. An_____________ is any system that aids GPS.
4. The GPS is a___________ that provides users with PNT services.
5. The space segment_____________ consists of 24 satellites.
6. The control segment____________ the satellites in their proper orbits.
7. The user's segment calculates the user's ___________position and time.
8. Major banks use GPS to____________ their computers around the world.
9. Many economic activities rely on precision timing for operational______.
Grammar Revision:Noun attributes and Passive Voice:
4.13 Read and translate the following word combinations paying attention
to nouns as attributes.
Remote control station, light pulses, light wave communications system, transmission system, telecommunications network, glass fiber, voice signal, data signal, television signal, telecommunications transmission, construction cost, underground duct, copper cable, signal regenerator, carrier system, device reliability, laser beam wave, radio wave speed, disaster- relief team, , one-way signal, three-dimensional position, on-time performance, advanced- driver assistant system, disaster-relief team, lane-change collision avoidance system, crash prevention, position notification.
4.14 Read the following sentences and say which of them are in the Active and which are in the Passive Voice. Translate them into Russian.
1. While the experiment was being carried out nobody left the station.
2. A new type of satellite equipment is being produced at our plant.
3. At present scientific work is being done mostly by large groups of researchers.
4. The apparatus will be working when you come.
5. The scientists who are carrying out research into radio astronomy deal with the most difficult problems.
6. For twenty minutes the air in the laboratory was being purified by two ventilators.
7. The solar battery is converting the energy of sun rays directly into electric energy.
8. This experiment was being carried out in vacuum.
9. For a long time the electronic devices were being used for control.
10. An interesting research in the field of electronics is being done at our Institute.
11. Prospects of the usage of solar energy are already understood by everybody.
12. Now solar energy is being studied by a lot of research groups.
13. Siberian scientists are developing new types of geostationary devices.
14. We were looking for a more simple method of solution but could not find it.
15. The engineers will discuss the advantages of this new system.
16. Our laboratory is housed in an old building.
17. A new navigation equipment is being examined by our scientists now.
4.15 Read text B and say if it covers the following ideas:
1. What is the name of the Chinese navigation system?
2. What countries develop the Galileo system?
3. What is driving the technological battle between Russia and US?
4. How many satellites does navigation system need?
5. What is the advantage of the GLONASS-capable GPS receiver?
Text B. GLONASS
The days of the cold war may have passed, but Russia and the United States are in the midst of another battle - this one a technological fight over the United States monopoly on satellite navigation. Nor is Russia the only country trying to break the American monopoly on navigation technology. China has already sent up satellites to create its own system, called Baidu after the Chinese word forthe Big Dipper1. And the European Union has also begun developing a rival system, Galileo, although work has been halted because of doubts among the private contractors over its potential for profits.
GLONASS is a radio-based satellite navigation system, developed by the former Soviet Union and now operated for the Russian government by the Russian Space Forces. Development on the GLONASS began in 1976. The constellation was completed in 1995, but the system rapidly fell into disrepair with the collapse of the Russian economy. Beginning in 2001, Russia committed to restoring the system by 2011, and in recent years has diversified, introducing the Indian government as a partner, and accelerated the program with a goal of global coverage by 2009 A fully functional GLONASS constellation consists of 24 satellites, with 21 operating and three on-orbitspares, deployed in three orbital planes. A characteristic of the GLONASS constellation is that any given satellite only passes over the exact same spot on the Earth every eighth sidereal day. However, as each orbit plane contains eight satellites, a satellite will pass the same place every sidereal day. For comparison, each GPS satellite passes over the same spot once every sidereal day.
There were three generations of the satellites. The true first generation of Uragan satellites were all 3-axis stabilized vehicles, generally weighing 1,250-kg.
These spacecraft demonstrated a 16-month average operational lifetime. The second generation of satellites, known as Uragan-M (also called GLONASS-M), possess a substantially increased lifetime of seven years and weigh slightly more - 1,480 kg. The latest designed generation of Uragan-K (GLONASS-K) spacecraft are the third generation of satellites. These satellites are designed with a lifetime of 10 to 12 years, a reduced weight of only 750 kg, and offer an additionalL-Band4 navigational signal. As with the previous satellites, these are 3-axis stabilized,nadir5 pointing with dual solar arrays.
By May 2007 the system remains partially operational. There were 11 satellites. In recent years, Russia has kept the satellite orbits optimized for navigating in Chechnya, increasing signal coverage there at the cost of degrading coverage in the rest of the world. GLONASS availability in Russia was 45.3% and average availability for the whole Earth was down to 30.5%, with significant areas of less than 25% availability. Meaning that, at any given time of the day in Russia, there is a 45.3% likelihood that a position fix can be calculated.
The Russian system is also calculated to send ripples through the fast-expanding industry for consumer navigation devices by promising a slight technical advantage over G.P.S. alone. Devices receiving signals from both systems would presumably be more reliable. "The network must be impeccable, better than G.P.S., and cheaper if we want clients to choose Glonass," Mr. Putin said at a Russian government meeting on the system.
1) 1the Big Dipper - Большая Медведица (the US and Canadian name for
the Plough (constellation).
2) 2spare- запасной (in reserve for use when needed).
3) 3axis - ось (a real or imaginary line about which a body, such as an
aircraft, can rotate or about which an object, form, composition, or geometrical
construction is symmetrical).
4) 4 L-Band - RF range 390 - 1550 MHz
5) 5nadir - надир (the point on the celestial sphere directly below an
observer and diametrically opposite the zenith).
4.16 Make up 10 questions to the text using the following constructions:
What is the (nature, difference, process, role, importance, etc.) of…?
What is referred to as….?
What is used as…?
Where do we use. …?
What function do the ... play?
1. Does Russia really need its own navigation system?
2. Does Kazakhstan need to have its own navigation system?
Последнее изменение этой страницы: 2016-03-17; Просмотров: 40; Нарушение авторского права страницы