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3 Choose from part II the appropriate continuation of the sentences.

1 Wire systems of communications are: ….

2 The telephone communication provides ….

3 When the recording of the received information is necessary, ….

4 Wireless system of ….

5 Radio communication is the transmission ….

6 Radio is the only method of ….

7 If the noise is great enough ….

8 Too much noise will lead to incomprehensible output ….

II 1. .... communication is radio communication.

2 .... and hence breakdown of the transmission.

3 …. trunk communication, telephone communication, telegraph communication.

4 …. it can significantly alter the decoded message.

5 …. the two-way communication with the subscribers.

6 …. and reception of messages without wires or waveguides.

7 …. the telegraph communication is used.

8 …. communication between stationary and mobile objects.

4 Translate without using a dictionary.

In a broadcast system, a central high-powered broadcast tower transmits a high-frequency electromagnetic wave to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The antenna of the receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).The broadcast media industry is at a critical turning point in its development, with many countries moving from analogue to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable integrated circuits. The chief advantage of digital broadcasts is that they prevent a number of complaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output.

5 Look at the following short descriptions of processes:

- The height of the pulse is measured and it is given a binary code.

- Each code is then transmitted as a train of pulses.

- First, by selecting suitable modulation frequencies the conversations can be placed next to each other.

- Then, they are transmitted as a group to the receive side where a similar station demodulates the signals and extracts the various conversations, before they are transmitted to another exchange.

Describe the following processes in a similar way:

a) - subscriber A /lift/ the handset

- wait for/ the dialing tone

- dial/ the number

- hear/ the ringing tone

- subscribe B / pick up/ the receiver

- conversation take place

- the two subscribers / replace/ the handsets

b) - the handset /lift

- a signal /send/ the exchange

- the exchange /send/ a dialing tone

- the number /dial

- subscriber B number /select/ in the exchange

- subscriber A number /connect/ subscriber B number

- conversation /take place

- handsets /replace

- connection /break