Text II Navigation

EXERCISE 1

Read text with the dictionary. Ask and answer questions about the text with your partner.

All satellite navigation systems use satellites with precision clocks. The satellite transmits its position, and the time of the transmission. The receiver listens to four satellites, and can figure its position as being on a line that is tangent to a spherical shell around each satellite, determined by the *time-of-flight of the radio signals from the satellite. A computer in the receiver does the math.

Radio direction-finding is the oldest form of radio navigation. Before 1960 navigators used movable loop antennas to locate commercial AM stations near cities. In some cases they used marine radiolocation beacons, which share a range of frequencies just above AM radio with amateur radio operators. Loran systems also used **time-of-flight radio signals, but from radio stations on the ground. VOR (Very High Frequency Omnidirectional Range), systems (used by aircraft), have an antenna array that transmits two signals simultaneously. A directional signal rotates like a lighthouse at a fixed rate. When the directional signal is facing north, an omnidirectional signal pulses. By measuring the difference in phase of these two signals, an aircraft can determine its bearing or ***radial from the station, thus establishing a line of position. An aircraft can get readings from two VOR and locate its position at the intersection of the two radials, known as a "fix." When the VOR station is collocated with DME (Distance Measuring Equipment), the aircraft can determine its bearing and range from the station, thus providing a fix from only one ground station. Such stations are called VOR/DMEs. The military operates a similar system of navaids, called TACANs, which are often built into VOR stations. Such stations are called VORTACs. Because TACANs include distance measuring equipment, VOR/DME and VORTAC stations are identical in navigation potential to civil aircraft.

*time-of-flight – пролет времени

**radial - 1) радиальный; лучевой; лучеобразный

radial road — радиальная дорога,

radial axle — радиальная ось

***navaid - 1) аэронавигационное вспомогательное оборудование, 2) средства обеспечения судовождения;

2) лучевой

EXERCISE 2

Speak about amplifiers, their role in communication and branches of use

Text III Global Positioning and Navigation Systems

EXERCISE 1

Read and translate the text.

The United States Global Positioning System (GPS) and the Russian Global Orbiting Navigation Satellite System (GLONASS) are networks of satellites that provide highly accurate positioning information from anywhere on Earth. Both systems use a group of satellites that orbit around the north and south poles at an altitude of 17,500 km (10,900 mi). These satellites constantly broadcast the time and their location above Earth. A GPS receiver picks up broadcasts from these satellites and determines its position through the process of triangulation. Using the time information from each satellite, the receiver calculates the time the signal takes to reach it. Factoring in this time with the speed at which radio signals travel, the receiver calculates its distance from the satellite. Finally, using the location of three satellites and its distance from each satellite, the receiver determines its position.

GPS services, originally designed for military use, are now available to civilians. Handheld GPS receivers allow users to pinpoint their location on Earth to within a few meters. One type of navigational tool used in automobiles integrates a GPS receiver with an intelligent compact disc player capable of displaying road maps and other graphical information. Upon receiving the GPS location data, the CD player can pinpoint the location visually on one of the road maps contained on disc.

EXERCISE 2

Study the vocabulary.

Global Positioning System (GPS) - глобальная (спутниковая) системаместоопределения

Global Orbiting Navigation Satellite System (GLONASS) - глобальная (спутниковая) орбитальнаясистеманавигации

accurate – точный

triangulation – триангуляция

handheld - ручной; передвижной, переносной, портативный

pinpoint - указатьточно

EXERCISE 3

Discuss the advantages of Global Positioning and Navigation Systems.

UNIT VII

FEEDERS

Text I

Antenna-feeder devices

EXERCISE 1

Read and translate the text using the following words and word combinations:

Antenna-feeder devices provide receiving and transmitting electromagnetic signals. Such devices consist of antenna, which radiates and receives radio waves, and feeder. Feeder is a cable or a waveguide which conducts oscillations from generator to the transmitting antenna and from receiving antenna to the receiver. Shape, size and configuration of the device could be different and depend on the length of a radiated and received wave.

Physical characteristics of antenna are the following:

• Wind load and vibration. In fact, antennas are usually placed on the roofs of buildings where wind load is maximum. So antenna’s construction and its bolting must withstand wind speed 160 km/h. Besides, antennas must be designed to undergo vibration up to 5 g (where g = 9,81 m/sec² ).

• The environmental temperature should be within – 40 ºC to + 50 ºC, so that antenna could operate continuously.

• Humidity and acing (frost) shouldn’t prevail 95%, otherwise antenna’s efficiency will get worse. But afterwards, when these factors stop effecting the antenna, its properties must be possible to restore.

Mass and configuration of antenna play important part in bolting and mounting, as well as in its positioning. Antenna-feeder devices are used in systems and complexes, including wireless radio communication. There are antennas of different shapes: a piece of wire, combination of such pieces, reflecting metallic mirrors, air holes with metallic walls and wire spirals.

EXERCISE 2

Words and word combinations to be remembered:

Feeder – 1)подающий механизм; питающий механизм; 2) фидер

waveguide – волновод

oscillation - колебание

toundergo - выдерживать

humidityandacing – влажность и обледенение

reflectingmetallicmirror – отражательное металлическое зеркало

EXERCISE 3

Would you like to work at an office? Why/ Why not? Make sentences about the office. The start is given to you in the table.

It’s…..	It isn’t…..
There’s a…..	There isn’t a…..
There are some …	There aren’t any …

Use words from the box below:

Computers office plants coffee machine small dark photographs

bookcase very tidy windows water fountain notice board

stationery bin