- •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
5 Translate in written form points 58.9:
PART 4 (58.9 - 58.16)
58.9 Digital telephones
Digital telephones are characterised by having the codec in the telephone to convert the speech from analogue to digital and vice versa. The PCM encoded speech is then sent to line-at a rate of 64kbit/s. In addition a 16kbit/s signalling channel is also present to send address and alerting signals to the exchange. CCITT have now defined standard interfaces for digital operation in the I series of recommendations, but many proprietary interfaces exist.
The I series specifies a 192kbit/s full duplex digital path between the digital telephone (terminal) located in the user's premises and the local exchange. The 192kbit/s is divided into a Bl channel (64kbit/s), a B2 channel (64kbit/s) and a D channel (16kbit/s). The В channels can be used for either voice or data. A digital telephone will consist of a handset and possibly handsfree loudspeaker and microphone connected to an integrated circuit, which will provide the functions of send, receive gain, frequency response, sidetone generation and the codec functions. Additional circuits are necessary to provide the physical drive to the line, extract power from the line and operate the link access procedure on the D channel (LAPD).
The functionality of the telephone can be built into the microprocessor software (functional model) or respond to stimulus signalling from the exchange (stimulus model). In the former all the call processing logic is designed into the telephone, whilst in the latter it is held centrally in the exchange and the telephone responds only to the messages from the exchange.
58.10 Telephone standards
European standards for telephones are country specific and contain many national peculiarities, which prevent the production of a single harmonised telephone suitable for use anywhere in Europe. NET 4 (Norme European de Telecommunication) for basic PSTN access was produced under an EEC directive in 1986 and covers all the essential parameters of signalling, transmission and safety. A new EEC directive in 1991 established the concept of CTRs (Common Technical Regulations) which will supersede the NETs with the aim of establishing the essential requirements to be regulated. The harmonised standards give the specifications and tests to be applied to ensure conformity with the requirements. The CTRs will not duplicate other requirements already in existence, such as the LVD (Low Voltage Directive). The objective is, some time in the future, to be able to test and approve telephones in one country in Europe, apply the EC Mark, and sell that telephone in any other country without further approval testing. At present each country issues its own national standards for telephones, either via the PTT as the controlling authority or via a national standards organisation such as BSI (British Standards Institute) in the UK.
In North America the position on standards for telephones is much simpler. The FCC (Federal Communications Commission) issues the basic standards for all of the USA and in Canada the DOC (Department of Communications) issues similar standards.