English in electronics and telecommunications

th transmission and switching equipment. The main advantage of this system is that the transmission loss encountered by speech becomes more or less independent of both distance and the number of exchanges through which a call is routed.
Stored Program Control (SPC) is the application of data processing and computer techniques to an exchange, thus providing a powerful, flexible method of controlling the operation of the exchange.
Common Channel Signalling (CCS) uses just one (go and return) pair of signalling channels, not directly associated with the traffic circuits, for performing all the signalling functions of an entire route which may contain several hundred traffic circuits.
Microelectronics technology is the application of solid-state semiconductor technology to provide components which range in function from a single active element (e.g. transistor) to large scale integrated circuits. Use of this technology offers small physical size and reliability, together with automated design, manufacture and testing. The components are fixed onto printed circuit boards, and if there is a fault, the defective printed circuit board can be taken out and replaced by another in a matter of seconds.
EXERCISE  C                  Complete the table
Classification
Electromechanical exchange
Digital exchange
Transmission type
Analogue transmission
Digital transmission and switching
Installation
a. ...................................
b. ...................................
Maintenance
High maintenance cost
c. ...................................
Low maintenance cost
d. ...................................
Technical comments
Crossed lines
e. ...................................
Rigidity of design 
Wrong numbers
f. ...................................
g. ...................................
h. ...................................
i. ...................................
j. ...................................
Much higher evolutionary potential
a. ...................................
EXERCISE  D      Match each of the headings with one set of functions
1.      Integrated Digital Transmission and Switching
2.      Stored Program Control
3.      Common Channel Signalling
4.      Microelectronics technology
A.    The application of solid-state semiconductor technology to provide greater reliability, smaller size and automated design.
B.     The application of data programming and  techniques to an exchange, thus providing a greater control and flexibility in the operative of the exchange.
C.     The use of one pair of channels not directly associated with the traffic circuits, to  perform all signalling functions on a complete route.
D.    Speech and other signals are digitally encoded and a common method of time-division multiplexing is used.
Writing
STAGE 1              Use Figure 2d to order the sentences below to form a text describing a simple FDM system.
The second and the third channels cannot be transmitted directly over the line.
At the receiving end, filters separate the three channels and finally demodulators restore channels 2 and 3 to their original frequency position.
To illustrate the principle of a frequency division multiplex (FDM) system, consider the simple case of transmission of 3 telephone channels.
Now, the three channels can be passed over the common line, boosted at intervals as necessary.
First, they are passed through a modulator which frequency shifts them to frequency bands 4 300 - 7 400 Hz and 8 300 - 11 400 Hz respectively.
The first of these channels can be transmitted directly over the common line and occupies the bandwidth 300 - 3 400 Hz.
STAGE 2              Use the above description of an FDM system as a model to write a description of a TDM system, using Figure 2e as a basis 
WORD  LIST  -  Unit 2
READING 1
1.      (N) The technique of transmitting light through long, thin, flexible fibres of glass, plastic, or other materials. Bundles of parallel fibres can transmit complete images.
2.      (V) To be reduced in strength or energy 
3.      (N) The presence of unwanted signals
4.      (N) The unwanted transfer of energy from one circuit to another
The sound is heard in a receiver along with a desired program because of cross modulation or other undesired coupling to another communication channel.
5.      (V) To partly cover something by extending over its edges
6.      (N) Dispersion and therefore fading of strength of pulse
7.      (N) An amplifier and associated equipment that processes weak signals and retransmits stronger signals without reshaping their waveforms. It can be one-way or two-way.
It is used in telephone lines, undersea cable, and fibre optic cables to overcome the effect of signal attenuation in the transmission media.
8.      (N) The region in which light can pass through
9.      (N) The region in which light can not pass through
10.  (N) Silicon dioxide
11.  (N) The ratio of the velocity of a wave in a vacuum to that in a specified medium
12.  (N) Differing successively in expansion characteristics
13.  (ADJ) Having a single sudden change in amplitude and a period of time at the new amplitude value
14.  (N) A semiconductor PN junction diode which converts electrical energy into light
15.  (N) A semiconductor PN junction diode which is sensitive to light, causing a reverse current to flow when light shines on it; or in another to say, the reverse current varies with illumination.
16.  (N) (Abbreviated to APD) A photodiode operated in the avalanche breakdown region to achieve internal photocurrent multiplication, thereby providing rapid light-controlled switching operation. It can have infra-red responnse, as required for detection of modulated light from lasers or LEDs.
It absorbs photons in the P-type region near its PN junction and generates electrons that traverse the lighter doped P-type 
17.  (N) (Abbreviation for Positive-Intrinsic-Negative) A semiconductor structure that has a high-resistance intrinsic region between low-resistance P and N- type regions. Microwave diodes, photodiodes, switching diodes, and voltage dependent variable resistors are made with this structure.
18.  (N) A detector that responds to radiant energy; i.e. energy transmitted in the form of electromagnetic radiation, such as radio waves, heat waves, and light waves.
It is also called a light detector, light sensitive cells, light sensitive detector, or photosensor.
READING 2
19.  (N) The actual power that is lost in transmitting a signal from one point to another through a medium or along a line
20.  (N) A control system using a digital computer that can translate or otherwise alter an input program by using internally storeed instructions and ten executing the rewritten program.
21.  (N) The technology of constructing and using electronic circuits and devices in extremely small packages through the use of integrated circuits or other special manufacturing techniques.
It is also called micro-miniaturization.
WRITING
22.  (N) A multiplex system for transmitting two or more signals over a common path by using a different frequency band for each signal
23.  (V) To change the frequency of a radio transmitter and oscilator
24.  (N) A filter that transmits alternating currents below a given cut-off frequency and substantially attenuates all other currents.
(N) A filter that allows only the band of frequencies to pass without attenuation. Frequency above and below the passband are rejected.
(N) A frequency band in which the attenuation of a filter is essentially zero.
25.  (N) (Abbreviated to PAM) Amplitude modulation of a pulse carrier
26.  (N) (Abbreviated to PCM) Modulation in which the peak-to-peak amplitude range of the signal to be transmitted is divided into a number of standard values, each value having its own three-place code. Each sample of the signal is then transmitted as the code for the nearest standard amplitude.  
27.  (N) A decoder that extracts useful information from a pulse-coded signal
28.  (N) A device which accepts distorted pulses and produces well-formed pulses
CONTENTS
Page
Unit 1
4
5
6
7
8
SECTION 1                  ELECTRONICS
Introduction to Conductivity
Reading and Comprehension
Word study                   Describing shapes
                                      Word formation 1- Suffixes
Language study       1.  Describing position and connection
                                2.  Relative clauses
                               3.   Pronoun links between sentences 
Information transfer      Mathematical symbols
Guided Writing                       Describing a diagram
Summarizing               Superconductivity
Unit 2
Semiconductor diodes
Reading and Comprehension
Word study                   Word formation 1- Prefixes
Language study       1.  Writing instruction - Describing an experiment - 
                                     Reporting an experiment
                                2.  Describing graphs
                               3.   Time clauses
Information transfer      Transistor characteristics
Guided Writing                       Writing explanations
Summarizing                Modulation
Unit 3
Alarm systems
Reading and Comprehension 1
Reading and Comprehension 2
Word study                          Compound nouns 
Language study        1. If-sentences - Unless
                                 2. Reduced time clauses
Information transfer     Understanding diagrams 
Writing                                    Linking facts and ideas
Unit 4
High definition television
Reading and Comprehension
Word study                  Circuit symbols
Language study               1. Expressing the Certainty
                                  2. Reason and result connectives
Information transfer     Logic gates
Writing                        Making paragraphs                 
Unit 1
Unit 2
SECTION 2               TELECOMMUNICATIONS
Networks
Transmission