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3. Ознакомьтесь с дополнительными словами и выражениями:

random ['rændəm] - случайный, произвольный

span – отмерять, охватывать

yield [jiːld] - давать результат, приводить (к чему-л.)

essentially [ɪ'senʃ(ə)lɪ] - по существу, существенно; в высшей степени; чрезвычайно

directional antenna - направленная антенна

omnidirectional antenna - ненаправленная антенна

4. Ответьте на следующие вопросы:

1. How many types does signal degradation fall into? 2. What do noise and distortion result in? 3. Give the definition of dissipation. 4. What are the factors to consider when choosing transmission media? 5. What main transmission media do modern telecommunications systems employ? 6. Why are noise and distortion undesirable in signals? 7. In wire transmission an information-bearing electromagnetic wave isn’t guided along a wire conductor to a receiver, is it?

5. Прочитайте предложения и определите истинны они или ложны:

1. The degradation of signals is caused by the environment through which they propagate. 2. Attenuation does not influence signal reception. 3. The choice of transmission medium depends purely upon its cost and availability. 4. Optical media use a rather narrow range in electromagnetic spectrum. 5. Radio transmission doesn't require any conductiong medium.

6. Найдите в тексте слова и выражения, эквивалентные данным ниже:

Приводить к ошибкам; уменьшаться наполовину; эффективность передачи сигнала; простота установки и обслуживания; проводящий материал; преобразование в тепло; электрический ток; электрическое споротивление; монохроматический свет; удаленный; заново преобразовывать.

7. Переведите на русский язык следующие словосочетания:

Information-bearing electromagnetic signal; intended information signal; channel attenuation; attenuation spectrum; dissipative loss; high-rate broadband telecommunication; far-infrared and near-infrared frequency; point-to-point radio channel.

8. Вставьте пропущенные слова:

attenuation, dissipation, conversion, plot, degrade, noise ,distortion

1. All transmitted signals are to some extent … by the environment through which they propagate. 2. Reduction in power is called … . 3. … is any undesired change in the amplitude or phase of any component of an information signal that causes a change in the overall waveform of the signal. 4. The … of channel attenuation as the signal frequency is varied is known as the attenuation spectrum. 5. … and distortion are commonly introduced by all transmission media. 6. Since all practical conductor materials are characterized by some electrical resistance, part of the electric current is always lost by … to heat.

9. Вставьте пропущенные предлоги:

1. All transmitted signals are degraded by the environment … which they propagate. 2. The principal cause … power loss is dissipation. 3. A radiating antenna converts a time-varying electric current … an electromagnetic wave or field. 4. Signal degradation generally falls … three types: noise, distortion, and attenuation . 5. Propagation of the wave is always accompanied … a flow of electric current through the conductor. 6. Optical wavelengths are naturally suited … high-rate broadband telecommunication. 7. Both noise and distortion are commonly introduced … all transmission media, and they both result in errors in reception.