Radiotechnical Communication Components. Радиотехнические средства связи. Учебное пособие

10. Translate the following sentences. Note the words which help you to define whether the word with the suffix -ing is a Verbal Noun, a Gerund or a Participle.

1.Our aim is solving this complex problem.

2.They succeeded in obtaining good results working with this metal.

3.The building of the house will be finished next month.

4.In testing the devices they found some serious faults.

5.The growing importance of automatic equipment in industry attracts world-wide attention.

6.Russian scientists played a great role in the spreading of the metric system in Russia.

7.After graduating from Petersburg University A.S. Popov remained there as a post-graduate at the Physics Department.

8.After Hertz had published his experiments proving the existence of electromagnetic waves, A.S. Popov thought of a possibility of using Hertz waves for transmitting signals over a distance.

9.On March 24, 1896 he demonstrated the transmission and reception of a radiogram consisting of two words: Heinrich Hertz.

10.Using the new method it is possible to increase accuracy and speed of spectral analysis.

11.Thousands of scientists, using the most modern equipment, are studying the atmosphere.

11. Translate the following sentences paying attention to the functions of the Gerund.

1.Large-scale application of electronic technique is a trend of technical progress capable of revolutionizing many branches of industry.

2.The physicists have developed a method for using optical quantum generators for spectral analysis.

3.When atoms or molecules are excited they emit electromagnetic waves. By counting the number of waves in a certain period, a very accurate measure of time can be defined.

4.The operating speeds of these systems will be measured in nanoseconds.

5.Telemetry is the science of seeing some place without being there.

6.Electronics is not so much a new subject as a new way of looking at electricity.

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7.These scientists continue working in this promising field of knowledge.

8.We know of Yoffe's having contributed much to the research of transistors.

Speaking

12.Write out of the text the words and phrases describing a laser. Speak about them.

13.Read the text and say where masers are used.

Writing

14. Write the summary of the text "Lasers and Masers ".

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1.the radar radiates electromagnetic energy from an antenna to propagate in space;

2.some of the radiated energy is intercepted by a reflecting object, usually called a target, located at a distance from the radar;

3.the energy intercepted by the target is reradiated in many directions;

4.some of the reradiated (echo) energy is returned to and received by the radar antenna;

5.after amplification by a receiver and with the aid of proper signal processing, a decision is made at the output of the receiver as to whether or not a target echo signal is present. At that time, the target location and possibly other information about the target is acquired.

A common waveform radiated by a radar is a series of relatively narrow, rectangular-like pulses. An example of a waveform for a medium-range radar that detects aircraft might be described as a short pulse one millionth of a second in duration (one microsecond); the time between pulses might be one millisecond.

Some radars have to detect targets at ranges as short as the distance from behind home plate to the pitcher's mound in a baseball park (to measure the speed of a pitched ball), while other radars have to operate over distances as great as the distances to the nearest planets. Thus, a radar might be small enough to hold in the palm of one hand or large enough to occupy the space of many football fields.

Radar targets might be aircraft, ships, or missiles; but radar targets can also be people, birds, insects, precipitation, clear air turbulence, ionized media, land features (vegetation, mountains, roads, rivers, airfields, buildings, fences, and power-line poles), sea, ice, icebergs, buoys, underground features, meteors, aurora, spacecraft, and planets.

In addition to measuring the range to a target as well as its angular direction, a radar can also find the relative velocity of a target either by determining the rate of change of the range measurement with time or by extracting the radial velocity from the Doppler frequency shift of the echo signal. If the location of a moving target is measured over a period of time, the track, or trajectory, of the target can be found from which the absolute velocity of the target and its direction of travel can be determined and a prediction can be made as to its future location.

Properly designed radars can determine the size and shape of a target and might even be able to recognize one type or class of target from another.

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After-reading tasks

1.The radar radiates electromagnetic energy from an antenna to propagate in space.

2.Some of the radiated energy is intercepted by a reflecting object, usually called a target, located at a distance from the radar.

3.The energy intercepted by the target is reradiated in many directions.

4.Some of the reradiated (echo) energy is returned to and received by the radar antenna.

5.After amplification by a receiver and with the aid of proper signal processing, a decision is made at the output of the receiver as to whether or not a target echo signal is present.

6.A common waveform radiated by a radar is a series of relatively narrow, rectangular-like pulses.

7.A radar might be small enough to hold in the palm of one hand or large enough to occupy the space of many football fields.

8.Radar targets might be aircraft, ships, or missiles; but radar targets can also be people, birds, insects, precipitation, clear air turbulence, ionized media, land features, sea, ice, icebergs, buoys, underground features, meteors, aurora, spacecraft, and planets.

9.Properly designed radars can determine the size and shape of a target and might even be able to recognize one type or class of target from another.

Word building

4. Form nouns adding the suffixes -er, -or to the given verbs. Translate the nouns and verbs into Russian.

Example:

to design – a designer (конструировать – конструктор)

1.to drive

2.to translate

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3.to visit

4.to convert

5.to regulate

6.to accumulate

8.to react

9.to use

10.to record

Grammar

5. Translate the following word groups into Russian, pay attention to the tense and the forms of the verbs.

1.the question has been solved

2.the error will have been determined

3.the point of view has influenced

4.the chemist has written

5.the number has exceeded

6.the energy had been converted

7.the radio has been transmitting

Speaking

6.Describe the operation of a radar.

7.Speak about radar targets.

8.Find some more information about radar. Prepare the presentation.

Writing

9. Write the summary of the text "Radar in brief ".

Lesson 2. Basic Parts of a Radar

Preview

Before you read

1.What can you say about the basic parts of a radar?

2.What is the ultimate limitation on the ability of a radar to make a reliable detection decision and extract information about the target?

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5spatial filter to фильтр пространственных частот

6local oscillator излучатель генератор

7low noise amplifier усилитель с низким уровнем собственных шумов

Reading

1. Read the text.

Basic Parts of a Radar

There are several subsystems usually found in a radar.The transmitter generates a suitable waveform for the particular job the radar is to perform. It might have an average power as small as milliwatts or as large as megawatts. (The average power is a far better indication of the capability of a radar's performance than is its peak power.) Most radars use a short pulse waveform so that a single antenna can be used on a time-shared basis for both transmitting and receiving.

The function of the duplexer is to allow a single antenna to be used by protecting the sensitive receiver from burning out while the transmitter is on and by directing the received echo signal to the receiver rather than to the transmitter.

The antenna is the device that allows the transmitted energy to be propagated into space and then collects the echo energy on receive. It is almost always a directive antenna, one that directs the radiated energy into a narrow beam to concentrate the power as well as to allow the determination of the direction to the target. An antenna that produces a narrow directive beam on transmit usually has a large area on receive to allow the collection of weak echo signals from the target.

The antenna not only concentrates the energy on transmit and collects the echo energy on receive, but it also acts as a spatial filter to provide angle resolution and other capabilities.

The receiver amplifies the weak received signal to a level where its presence can be detected. Because noise is the ultimate limitation on the

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ability of a radar to make a reliable detection decision and extract information about the target, care is taken to insure that the receiver produces very little noise of its own. At the microwave frequencies, where most radars are found, the noise that affects radar performance is usually from the first stage of the receiver, shown here in the figure as a low-noise amplifier.

After-reading tasks

2. Answer the questions.

1.What are the technical characteristics of a radar that must be of interest for radar transmitter users?

2.What are the subsystems usually found in a radar?

3.What does the antenna allow?

4.What is the function of the receiver?

5.What is the ultimate limitation on the ability of a radar to make a reliable detection decision and extract information about the target?

3.Find sentences which give the main idea of each paragraph of the text given above and put them down.

4.Translate the sentences.

1.The transmitter generates a suitable waveform for the particular job the radar is to perform.

2.The function of the duplexer is to allow a single antenna to be used by protecting the sensitive receiver from burning out while the transmitter is on and by directing the received echo signal to the receiver rather than to the transmitter.

3.The antenna is the device that allows the transmitted energy to be propagated into space and then collects the echo energy on receive.

4.The receiver amplifies the weak received signal to a level where its presence can be detected.

5.Write the summary of the text "Basic Parts of a Radar"

6.Read the text and make the glossary to it. Translate the text from English into Russian. Make the outline of the text and retell it according to it.

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cessing that maximizes the signal-to-clutter ratio of a moving target when clutter is larger than receiver noise, and it separates one moving target from other moving targets or from clutter echoes. The detection decision is made at the output of the receiver, so a target is declared to be present when the receiver output exceeds a predetermined threshold. If the threshold is set too low, the receiver noise can cause excessive false alarms. If the threshold is set too high, detections of some targets might be missed that would otherwise have been detected. The criterion for determining the level of the decision threshold is to set the threshold so it produces an acceptable predetermined average rate of false alarms due to receiver noise.

After the detection decision is made, the track of a target can be determined, where a track is the locus of target locations measured over time. This is an example of data processing. The processed target detection information or its track might be displayed to an operator; or the detection information might be used to automatically guide a missile to a target; or the radar output might be further processed to provide other information about the nature of the target. The radar control insures that the various parts of a radar operate in a coordinated and cooperative manner, as, for example, providing timing signals to various parts of the radar as required.

The radar engineer has as resources time that allows good Doppler processing, bandwidth for good range resolution, space that allows a large antenna, and energy for long range performance and accurate measurements. External factors affecting radar performance include the target characteristics; external noise that might enter via the antenna; unwanted clutter echoes from land, sea, birds, or rain; interference from other electromagnetic radiators; and propagation effects due to the earth's surface and atmosphere. These factors are mentioned to emphasize that they can be highly important in the design and application of a radar.

Word Building

7. Form nouns adding the suffix - ity to the given verbs and adjectives and translate them.

Example:

stable – устойчивый stability – устойчивость

1.real

2.active

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