- •Учреждение образования «высший государственный колледж связи» «чтение и перевод технических текстов по специальности ткс»
- •Часть II
- •Unit 3 Time Division Multiplexing
- •21.1 General definition
- •21.2 Digital time division multiplex structure
- •21.2.1 Frame organisation
- •21.2.2 Frame alignment
- •21.2.3 Signalling
- •1 Learn the words & word combinations:
- •4 Answer the questions:
- •21.3 The digital hierarchy levels
- •21.4 The t carrier framing and coding formats
- •The superframe format
- •21.4.2 The extended superframe format
- •21.4.3 Clear channels for data applications
- •1 Learn the words & word combinations:
- •4 Answer the questions:
- •21.5 The cept pcm-30 framing format
- •21.5.1 Frame composition
- •1 Learn the words & word combinations:
- •21.6.2 Error conditions
- •21.7 Coding schemes
- •1 Learn the words & word combinations:
- •4 Answer the questions:
- •Unit 4 (58) Telephones and headsets
- •58.1 Telephones
- •58.2 Telephone speech functions
- •58.3 Telephone transmitters
- •58.3.1 Carbon granule transmitter
- •58.3.2 Rocking armature transmitter
- •58.3.3 Piezoelectric transmitter
- •58.4 Telephone receivers
- •58.4.1 Rocking armature receiver
- •58.4.2 Moving coil receiver
- •1. Learn the words & word combinations:
- •4. Answer the questions:
- •5. Translate in written form point 58.3.1:
- •58.5 Telephone handset design
- •58.6 Telephone transmission performance
- •58.6.1 Sending sensitivity
- •58.6.2 Receive sensitivity
- •58.6.3 Impedance
- •58.6.4 D.C. Characteristics
- •1 Learn the words & word combinations:
- •3 Find English equivalents:
- •Answer the questions:
- •5 Translate in written form points 58.6.1 – 58.6.4:
- •58.7 Signalling
- •Incoming ringing signals
- •Outgoing 48raveling
- •Dial pulse or loop disconnect 49raveling
- •Dual tone multifrequency 50raveling
- •Loudspeaking telephones
- •1 Learn the words & word combinations:
- •4 Answer the questions:
- •5 Translate in written form points 58.9:
- •58.9 Digital telephones
- •58.10 Telephone standards
- •58.11 Headsets
- •58.12 Headset aesthetics
- •58.13 Headset technical considerations
- •58.13.1 Microphones
- •58.13.2 Earphones
- •58.14 The growing need for headsets
- •58.15 Headset approval process
- •58.16 Headset design criteria
- •1 Learn the words & word combinations:
- •Unit 5 (60) Facsimile transmission
- •60.2 Facsimile types
- •60.2.1 Photofax equipment
- •60.2.2 Weatherfax equipment
- •60.2.3 Pagefax equipment
- •60.2.4 Mobile equipment
- •60.2.5 Government and military equipment
- •60.2.5.1 Strategic requirements
- •60.2.5.2 Tactical requirements
- •60.3 Ccitt document facsimile equipment
- •1 Learn the words & word combinations:
- •3 Find English equivalents:
- •4 Answer the questions:
- •5. Translate in written form points 60.3.4:
- •60.4 G3 facsimile equipment
- •60.4.1 Scanner
- •60.4.2 Data compression
- •60.4.2.1 Modified Huffman
- •60.4.2.2 Modified read
- •60.4.3 Modulation and demodulation
- •60.4.3.1 G3 signal transmission
- •60.4.3.2 Modem operation
- •60.4.3.3 14.4Kbills option
- •1 Learn the words & word combinations:
- •2 Find Russian equivalents; mind the meaning of these expressions:
- •60.4.4.1 Ecm receiver operation
- •60.4.4.2 Ecm performance
- •60.4.5 Printer
- •60.4.6 G3 handshake protocol
- •60.5 64Kbit/s facsimile equipment
- •60.5.1 G4 equipment
- •60.5.2 64Kbit/s g3 type equipment
- •1 Learn the words & word combinations:
- •2 Find Russian equivalents; mind the meaning of these expressions:
- •3 Answer the questions:
- •5. Translate in written form points
- •60.6 G3 networks, switches, gateways and pc fax.
- •60.6.1 Managed network use
- •60.6.2 Facsimile switches
- •60.6.3 Facsimile gateways
- •60.6.4 Pc fax cards
- •60.7 Facsimile futures
- •1 Write out all the words unknown to you, learn them properly.
- •2 Translate in written form points 60.6 – 60.7
- •«Чтение и перевод технических текстов по специальности ткс»
- •Часть II
58.6.4 D.C. Characteristics
Most telephones which are directly connected to the exchange via a pair of wires derive their power from a central battery in the exchange, which feeds current down the line normally from a -48V or -50V supply. Some earlier telephone systems operated on local batteries, next to the telephone on the customer's premises, but this method of operation is now only reserved for special applications e.g. radio telephones. The exchange battery feed circuit is usually a Stone or a Hayes bridge. The battery feed has balanced windings with respect to earth and presents a relatively low d.c. resistance, but a high impedance to voice frequencies. The d.c. resistance is usually around 200 ohms in the battery feed and the same in the ground return with an inductance of 2 Henrys.
The d.c. characteristics of a telephone are important as they determine the operating parameters for the telephone. It is normal to have a full bridge rectifier at the front end of any telephone circuit, to guard against line reversals which may damage speech and dialling circuits. When the telephone is idle (on-hook) the telephone will extract current from the line. This is normally only insulation resistance leakage and is of the order of a few micro amperes. However, some telephone network providers permit more current to be taken from the line when the telephone is on-hook, to power electronic memory devices in the telephone or LCD displays.
When the telephone is off-hook current is drawn from the network to power the telephone. The telephone network providers set limits to the amount of current that may be drawn and the telephone must operate within the parameters set. The d.c. characteristics are normally specified by a relationship between current and voltage, as in Figure 58.10.
The upper limits are set to ensure that the telephone will be able to seize and hold the exchange equipment. The off-hook impedance of a telephone should be equal to or greater than the 400 ohms battery feed, to obtain optimum voice signal power transfer in the 200Hz to 3400HZ voice frequency range. Many telecommunication administrations set a lower limit on the voltage that a telephone should operate on, because it is not desirable to subject the feed bridge circuit to a short circuit. However, this is not normally the practical reason since the cable from the exchange must be present. The more practical reason is the need to easure that sufficient current is available for more than one telephone to operate in parallel.
1 Learn the words & word combinations:
Mouthpiece |
Микрофон |
Reliability |
Надежность |
Complain |
Жаловаться |
Sufficient |
Достаточный |
Impair |
Ухудшать |
essential |
Важный |
partially |
Частично |
speech power levels |
Уровни речевой мощности (уровни чувствительности микрофона) |
ambient |
Окружающий |
protect |
Защищать |
seize |
Схватить (занимать временной интервал) |
hookswitch |
Рычажный переключатель |
cradleswitch |
Рычажный переключатель |
abuse |
Плохое обращение |
withstand |
Противостоять |
assess |
Оценить |
compare |
Сравнивать |
loudness rating |
Уровень громкости |
value |
Значение |
relate |
Относиться |
perceive |
Принимать |
a sound absorbing box |
Звуконепроницаемая коробка (звуко-поглощающий блок) |
clamped jig |
Зажимное приспособление |
severe |
Суровый |
meet requirements |
Соответствовать требованиям |
telephone handset |
Микротелефонная трубка |
Ergonomic |
Эргономика |
Earpiece |
Головной телефон, наушники |
Seal |
Уплотнение устройства. Уплотнение |
Sidetone |
|
Acoustic feedback |
Акустическая обратная связь |
Ambient noise |
Шум окружающей среды |
Acoustic shock |
Акустический удар |
Telephone circuit |
Телефонная линия |
Transient |
Переходной процесс, переходное или преходящее явление, переходное состояние |
Power surge |
(большой) выброс мощности |
Discharge |
Разряд |
To seize |
Занимать временной интервал |
Sensitivity |
Чувствительность |
Line impedance |
Входное полное сопротивление (входной импеданс) линии передачи |
Frequency range |
Диапазон частот, полоса частот |
Line current |
Линейный ток |
Transmission path |
Тракт передачи, канал передачи |
Rating |
Номинальное значение |
Speech path |
|
Termination |
|
Anechoic chamber |
Безэховая камера |
Terminating impedance |
Входное (или выходное) полное сопротивление |
PCM circuit (pulse-code modulation) |
Схема ИКМ (импульсно-кодовая модуляция) |
Hum pickup |
Фоновая наводка |
Main |
Магистральная линия |
To sample |
Производить отсчёт, выборку |
Sampling frequency |
Частота дискретизации, частота выборки |
Digital exchange |
Цифровая АТС |
Bidirectional |
Двунаправленный |
Wire circuit |
Проводная линия |
Wheatstone bridge |
Мост для измерения сопротивления, мост Уитстона |
decoupling |
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2 Find Russian equivalents:
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