- •Учреждение образования «высший государственный колледж связи» «чтение и перевод технических текстов по специальности ткс»
- •Часть I
- •Введение
- •Unit 1 (17) Antennas
- •17.1 Types of antennas
- •17.1.1 Antennas used in communications
- •17.2 Basic properties
- •17.3 Generic antenna types
- •17.3.1 Radiation from apertures
- •1 Learn the words & word combinations:
- •2 Read & translate the text (orally) 17.1 – 17.3.2:
- •5 Answer the questions:
- •17.3.2 Radiation from small antennas
- •17.3.3 Radiation from arrays
- •17.4 Specific antenna types
- •17.4.1 Prime focus symmetric reflector antennas
- •17.4.1.1 Parabolic reflectors
- •17.4.1.2 Aperture fields and radiation patterns
- •17.4.1.3 Gain of reflector antennas
- •1Learn the words & word combinations:
- •2 Read & translate the text (orally) 17.3.2 – 17.4.1:
- •5 Answer the questions:
- •17.4.2 Dual symmetric reflector antennas
- •17.4.3 Offset reflectors
- •17.4.4 Horn feeds for reflector antennas
- •17.4.4.1 Rectangular or square horns
- •17.4.4.2 Small conical horns
- •17.4.4.3 Multi-mode conical horns
- •17.4.4.4 Conical corrugated horns
- •17.4.4.5 Array feeds
- •1 Learn the words & word combinations:
- •2 Read & translate the text (orally) 17.4.2 – 17.4.4:
- •5 Answer the questions:
- •17.5 Antennas used in communication systems
- •17.5.1 Microwave line of sight radio
- •17.5.2 Earth station antennas
- •1 Learn the words & word combinations:
- •2 Read & translate the text (orally) 17.5.1 – 17.5.2:
- •5Answer the questions:
- •17.5.3 Satellite antennas
- •17.5.3.1 Telemetry, tracking and command (tt&c)
- •17.5.3.2 Spot beams
- •17.5.3.3 Multiple beams
- •17.5.3.4 Shaped beams
- •17.5.4 Vhf and uhf communications
- •17.5.5 Hf communications
- •1 Write out the words and word combinations which are still unknown to you and learn them. Unit 2 (20) Frequency division multiplexing
- •20.1 Fdm principles
- •20.2 History
- •20.3 Fdm hierarchy
- •20.3.1 General considerations
- •20.3.2 Channel bandwidth
- •20.3.3 Group and supergroup
- •20.3.4 Higher order translation
- •20.3.4.1 15 Supergroup assemblies
- •20.3.4.2 Mastergroup
- •20.3.4.3 Bell system
- •1 Learn the words & word combinations:
- •2 Read & translate the text (orally) 20.1 – 20.3.4:
- •4Find English equivalents:
- •5 Answer the questions:
- •20.4 Frequency translation
- •20.4.1 Ring bridge modulator/demodulator design considerations
- •20.4.1.1 Carrier compression.
- •20.4.1.2 Carrier and signal suppression
- •20.5 Carriers
- •20.5.1 Carrier frequency accuracy
- •20.5.2 Carrier purity
- •20.5.3 Carrier level
- •20.6 Pilots
- •20.6.1 Translation equipment pilots
- •20.6.1.1 Use of reference pilots for automatic gain control
- •20.6.2 Line equipment pilots
- •20.6.2.1 Regulation pilots
- •20.6.2.2 Frequency comparison pilots
- •1 Learn the words & word combinations:
- •2 Read & translate the text (orally) 20.4 – 20.6
- •5. Answer the questions:
- •20.7 Noise contributions
- •20.7.1 Definitions
- •20.7.2 Psophometric weighting
- •20.7.3 Thermal noise
- •20.7.4 Noise due to unlinearity
- •20.7.4.1 Single channel load
- •20.7.4.2 Multichannel load
- •20.7.4.3 Unlinearily characterisation
- •20.7.4.4 Determination ofunlinearity noise from a multichannel load
- •20.7.4.5 Approximate value for the weighted intermodulation noise contribution
- •20.7.4.6 Weighted noise power in pWOp
- •20.7.4.7 Determination of unlinearity noise using spectral densities
- •1 Learn the words & word combinations:
- •2 Read & translation the text (orally) 20.7:
- •5 Answer the questions:
- •20.8 Measurement of noise contributions
- •20.9 Overload
- •20.9.1 Overload measurement.
- •20.9.1.1 Harmonic/intermodulation products
- •20.9.1.2 Gain change
- •20.10 Hypothetical reference system
- •20.10.1 Noise contributions
- •20.10.2 Line sections
- •1 Learn the words & word combinations:
- •2 Read & translate the text (orally) 20.8 -20.10:
- •5 Answer the questions:
- •20.11 Companding
- •20.11.1 Compander characteristics
- •20.11.2 Multichannel load increase
- •20.11.3 Compandor noise advantage
- •20.13 Transmultiplexers
- •20.13.1 Synchronisation
- •20.13.2 Pcm alarms
- •20.14 Repeatered cable line equipment
- •20.14.1 Pre-Emphasis
- •20.14.2 Thermal noise
- •20.14.3 Regulation
- •20.14.3.1 Regulation range
- •20.14.4 Power feeding
- •Translate the text 20.11 – 20.14.4
- •Translate in written form point 20.13 “Transmultiplexers”
- •«Чтение и перевод технических текстов по специальности ткс»
- •Часть I
Учреждение образования «высший государственный колледж связи» «чтение и перевод технических текстов по специальности ткс»
Методическое пособие
по дисциплине «АНГЛИЙСКИЙ ЯЗЫК»
Часть I
для студентов уровня ВО, 3 курс, 5 семестр
специальности 1-45 01 03 – Сети телекоммуникаций
Минск 2005
|
Составитель |
И.Н. Ращинская |
В методическую разработку вошли 5 текстов из оригинального учебника для специальности «Сети телекоммуникаций»:
Antennas
Frequency Division Multiplexing
Time Division Multiplexing
Telephones & Headsets
Facsimile transmission
Рецензент |
Е.М. Игнатьева |
Издание утверждено на заседании кафедры ГН
«__» ______ 2004г., протокол № __
Зав.кафедрой ____________Л.П. Томилина
Содержание
Введение |
4 |
|
UNIT 1 (17) Antennas |
||
|
Part 1 |
5 |
|
Part 2 |
13 |
|
Part 3 |
21 |
|
Part 4 |
27 |
|
Part 5 |
33 |
Unit 2 (20) Frequency division multiplexing |
||
|
Part 1 |
37 |
|
Part 2 |
43 |
|
Part 3 |
48 |
|
Part 4 |
59 |
|
Part 5 |
65 |
Введение
Методическая разработка составлена в помощь студентам и преподавателям для чтения технических текстов по специальности телекоммуникационные системы и имеет своей целью развитие навыков чтения и технического перевода.
Каждый урок имеет перечень активных слов и словосочетаний, наиболее часто встречающихся в технических текстах, которые рекомендованы для запоминания. Для тренировки и усвоения активной лексики рекомендуются для выполнения упражнения после текста.
Важную значимость представляет собой упражнение «ответить на вопросы», которое не только формирует умение ставить и отвечать на вопросы, но также способствует усвоению специальной лексики.
Тексты в основном имеют дополнительную часть (в конце), которая может быть использована для контрольного перевода по прохождению данного урока.
Unit 1 (17) Antennas
PART 1 (17.1 – 17.3.1)
17.1 Types of antennas
Antennas form the link between the guided parts and the free-space parts of a communication system. The purpose of a transmitting antenna is to efficiently transform the currents in a circuit or waveguide into radiated radio or microwave energy. The purpose of a receiving antenna is to efficiently accept the received radiated energy and convert it to guided form for detection and processing by a receiver. The design and construction of an antenna usually involves compromises between the desired electromagnetic performance and the mechanical size, mass and environmental characteristics.
Antennas for communication systems fall into two broad categories depending on the degree to which the radiation is confined. Microwave radio relay and satellite communications use pencil beam antennas, where the radiation is confined to one narrow beam of energy, Figure 17.1. Mobile communications are more likely to require antennas with omni-directional patterns in the horizontal plane and toroidal patterns in the vertical plane, Figure 17.2.
Pencil beam antennas usually consist of one or more large to medium reflectors which collimate the signals from a feed horn at the focus of the reflector. Both reflector and feed horn fall within the generic class of aperture antennas because they consist of an aperture which radiates into space. The design problem is to first determine the aperture fields which will yield the specified radiation characteristics and secondly to design the reflectors and horns to produce the aperture fields. Aperture antennas can be designed to meet very stringent specifications. Omni-directional antennas consist of elements which are small in wavelengths, such as dipoles and monopoles. The radiation characteristics are influenced by the presence of surrounding objects. Non-electromagnetic factors such as the size are often as important in the design as the radiation performance. For this reason the design of omni-directional antennas is partly an empirical process in which expertise and previous experience play an equal part with theoretical knowledge.
In between the large aperture antennas and the small element antennas lies array antennas which consist of two or more elements. The radiation from an array antenna is determined principally by the physical spacing and electrical signals driving the elements rather than the radiation characteristics of the elements themselves.
The detailed theory of antennas can be found in Stutzman (1981); Elliot (1981); Balanis (1982); Silver (1984); Colin (1969). Design information and descriptions of particular types can be found in a number of handbooks, such as, Rudge (1986); Johnson (1984); Lo (1988); Milligan (1985).