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.