Вопрос № 884774 - Английский язык

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A Radar System
1. A radar system has a transmitter that emits radio waves called radar signals in predetermined directions. When these come into contact with an object they are usually reflected and/or scattered in many directions. Radar signals are reflected especially well by materials of considerable electrical conductivity – especially by most metals, by seawater, by wet land, and by wetlands. The radar signals that are reflected back towards the transmitter are the desirable ones that make radar work. If the object is moving either closer or farther away, there is a slight change in the frequency of the radio waves, due to the Doppler effect.
2. Radar receivers are usually, but not always, in the same location as the transmitter. Although the reflected radar signals captured by the receiving antenna are usually very weak, these signals can be strengthened by the electronic amplifiers that all radar sets contain. The weak absorption of radio waves by the medium through which it passes is what enables radar sets to detect objects at relatively-long ranges – ranges at which other electromagnetic wavelengths, such as visible light, infrared light, and ultraviolet light, are too strongly attenuated. In particular, there are weather conditions under which radar works well regardless of the weather. Such things as fog, clouds, rain, falling snow, and sleet that block visible light are usually transparent to radio waves.
3. Finally, radar relies on its own transmissions, rather than light from the Sun or the Moon, or from electromagnetic waves emitted by the objects themselves, such as infrared wavelengths (heat). This process of directing artificial radio waves towards objects is called illumination, regardless of the fact that radio waves are completely invisible to the human eye or cameras.
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What enables radio waves to detect objects being far enough from radio transmitter?

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A Radar System
1. A radar system has a transmitter that emits radio waves called radar signals in predetermined directions. When these come into contact with an object they are usually reflected and/or scattered in many directions. Radar signals are reflected especially well by materials of considerable electrical conductivity – especially by most metals, by seawater, by wet land, and by wetlands. The radar signals that are reflected back towards the transmitter are the desirable ones that make radar work. If the object is moving either closer or farther away, there is a slight change in the frequency of the radio waves, due to the Doppler effect.
2. Radar receivers are usually, but not always, in the same location as the transmitter. Although the reflected radar signals captured by the receiving antenna are usually very weak, these signals can be strengthened by the electronic amplifiers that all radar sets contain. The weak absorption of radio waves by the medium through which it passes is what enables radar sets to detect objects at relatively-long ranges – ranges at which other electromagnetic wavelengths, such as visible light, infrared light, and ultraviolet light, are too strongly attenuated. In particular, there are weather conditions under which radar works well regardless of the weather. Such things as fog, clouds, rain, falling snow, and sleet that block visible light are usually transparent to radio waves.
3. Finally, radar relies on its own transmissions, rather than light from the Sun or the Moon, or from electromagnetic waves emitted by the objects themselves, such as infrared wavelengths (heat). This process of directing artificial radio waves towards objects is called illumination, regardless of the fact that radio waves are completely invisible to the human eye or cameras.
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Unlike visible light radio waves …

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Radio Systems
1. Radio systems used for communications will have the following elements. With more than 100 years of development, each process is implemented by a wide range of methods, specialized for different communications purposes. Each system contains a transmitter. This consists of a source of electrical energy, producing alternating current of a desired frequency of oscillation. The transmitter contains a system to modulate some property of the energy produced to impress a signal on it.
2. This modulation might be as simple as turning the energy on and off, or altering more subtle properties such as amplitude, frequency, phase, or combinations of these properties. The transmitter sends the modulated electrical energy to a tuned resonant antenna; this structure converts the rapidly changing alternating current into an electromagnetic wave that can move through free space.
3. The electromagnetic wave is intercepted by a tuned receiving antenna; this structure captures some of the energy of the wave and returns it to the form of oscillating electrical currents. At the receiver, these currents are demodulated, which is conversion to a usable signal form by a detector sub-system. The receiver is «tuned» to respond preferentially to the desired signals, and reject undesired signals.
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A Satellite Telephone
1. A satellite telephone, satellite phone, or satphone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites. They provide similar functionality to terrestrial mobile telephones: voice, short messaging service and low-bandwidth Internet access are supported through most systems. Depending on the architecture of a particular system, coverage may include the entire Earth, or only specific regions. The mobile equipment, also known as a terminal, varies widely.
2. Early satellite phone handsets had a size and weight comparable to that of a late-1980s or early-1990s mobile phone, but usually with a large retractable antenna. More recent satellite phones are similar in size to a regular mobile phone while some prototype satellite phones have no distinguishable difference from an ordinary smartphone. Satphones are popular on expeditions into remote areas where terrestrial cellular service is unavailable.
3. Since satellite phones are purpose-built for one particular network and cannot be switched to other networks, the price of handsets varies with network performance. If a satellite phone provider encounters trouble with its network, handset prices will fall, then increase once new satellites are launched. Similarly, handset prices will increase when calling rates are reduced.
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The Law and the Family
1. Beyond the mere function of providing a new generation of children, the family is often promoted for its moral contribution to society. Despite a growing labor shortage, the Japanese government has passed very little legislation challenging the assumption that mothers should stay at home rather than go out to work. In Ireland, which is strongly influenced by the doctrines of the Catholic Church, divorce remains illegal.
2. In some societies the family is thought to be so important that there is very little legal intervention in family life. In many Islamic countries, for example, fathers, brothers and sons are allowed considerable authority over the females in their family. As late as the 1970s, the male head of the household in Switzerland was deemed to represent the interests of everyone within that household, and, consequently, none of the women could vote in national elections.
3. But in many parts of the world, the law now promotes the rights of individuals within the family unit, and regulates family relations through legislation. Raised from the taxes of the working population as a whole, child benefit is paid directly to the mother, and retirement pensions are paid to grandparents, so that they are less dependent upon financial support from a family member. In Sweden, parents can be prosecuted for physically punishing their children and children have a limited capacity to divorce their parents. In Britain, as in many countries, there are special family courts with very strong powers to control and transfer private property in the interests of children. Much of the work of other courts is also directly relevant to family life.
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Federalism
1. State power has three main branches: legislative, executive and judicial. The legislature makes laws; the executive enforces the laws and governs the country; the judges decide disputes that come before them and in doing so interpret the law and apply it to the facts of the case they have to judge.
2. State power can also be divided upon a geographical basis. The system for doing this is called federalism. In a federal state there is a federal government, legislature and courts. There are also regional governments, legislatures and courts. Both may get their powers from a written constitution .Powers to make laws, to govern and to judge are each divided between the federal state and the regions. The regions go by different names in different countries (states, provinces, lands, cantons, republics).
3. One reason for dividing power in this way is that the country is too large to be governed conveniently from a single centre (the USA). Another is that its regions vary in language or culture (Switzerland, India, Canada). A third is that a central government might be too powerful if it was not balanced by regional governments with some independent powers (Germany, the USA).
4. In a typical federation defense and foreign policy belong to the federal government, education to the regions, and the power to tax is divided between the two. So the federation and the regions may both have power to make laws on similar subjects. Since each region has its own independent powers and courts, it has its own regional legal system, alongside the federal legal system. If the federation also separates the law-making, governing and judging functions the law becomes very complicated and expensive. But they allow a country to hold together when otherwise it would fall apart.
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