6.0 Principles of Telecommunication[1]

8/6/2019 6.0 Principles of Telecommunication[1]

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(E2002) ELECTRONIC SYSTEM 2

CHAPTER 6 TELECOMMUNICATION PRINCIPLE

CHAPTER 6

TELECOMMUNICATION PRINCIPLE

6.1 DEFINITION

a) Communication:

> The process of transferring information from someone to someone else.

b) Telecommunication:

> Technology that are used to send information in a great distance.

> Through this way information energy switched to electric power, electromagneticwaves and light by using suitable transducer.

> For example, the past communications are used smoke, flag, drum, mosque drum etc.

> Now, people are using internet, satellite, telemetry, facsimile, radio, radar, telegraphy,etc.

COMMUNICATION SYSTEM

Together with rapid progress, we also require sophisticated, efficient and savecommunication system. Various kinds telecommunication have been introduced in efforts tohelp human to facilitate and faster the information delivery process, such as telegraphy,facsimile, radar, radio communication move, satellite system, microwave etc.

general objective To know and understand telecommunication principlefundamentally, analogue and digital wave characteristic andthe relationship of frequency, wavelength, velocity ofpropagation, amplitude, phase and period of the wave.

specific objective At the end of this unit, you would be able to:

- define telecommunication definition- get relationship between frequency, wavelength, andvelocity of propagation.- list the analog and digital signal characteristic.- sketch the basic communication system block figure.- explain the basic communication system block figure.





TELEGRAPHY

This is a form of written delivery information in a great distance. The sent information willbe changed into coded signal. The codes that can be used top represent the information areMurray code or 5 beets code, and Morse code. In Morse code system, each sending letter will

be represented by combination code such as dot, dash and pause.The sending information can be achieved by using electromechanical equipment, which isshaped like typewriter, and is known as 'teleprinter'.When teleprinter key is impressed, voltage pulses signal will produced, for Murray code, -80Vand +80V voltage would be used to represent information that was impressed. This voltagepulses would be supplied to recipient teleprinter. Current pulses will be working onelectromagnet recipient teleprinter to print original information that will be sent, at the same timeone information copy also would be printed in recipient teleprinter.

Telephony

Is a process that delivery voice information (speech), in long distance, by using transmissionline such as coaxial cable, twisted wire cable, metal cable, etc. Tool used was telephone. Voiceinformation want to be sent will be turned to electric current by using suitable transducer intelephone namely carbon microphone. Delivery broad band signal was low that is in audiorange, between 300Hz to 3400Hz.

Facsimile

Information delivery technique in form pictures stationary, by using network telephony. Thisdelivery concept is reflected such as table below:

Telemetry

Is collecting technique and sending information in long distance through telephony network. Italways used to gauge river water, dam and variety of data height level natural.

Radar

Radar is a communication method to send wave pulses to direction of target and reflect againas signal received. Total time that is taken for information broadcasted and bounces back againdepends on target distance. Signal bounce back again will be analyzed to give information such

as distance, height, and angle of elevation something target. This system widely used inmilitary.

RADIO MOVE

Move radio communication is a form of bilateral communication which occurred between basicstations (base station) with one or more mobile unit. Frequency band used was UHF and VHF.It’s application more focused to cellular telephone service.





SATELLITE

There was some frequency classi) C-Band : 4-6 GHzii) Ku-Band :12-14 GHziii) Ka-Band : 20-30 GHz

Has the capacity to:i) bring data with hectic pace.ii) cheap cost.iii) include wide area.iv) charge service does not depend on distance.

. this system use VSAT ( Very Small Aperture Terminal) to receive data.

. main problem of satellite system is from data security factor and rain interference.

MICROWAVE

> Use parabolic disk to get and send data.> transferring must be in form 'line of sight'- namely which means could not be deterrent.> this system suitable to be used in those areas are difficult to install cable line.> this type of system also simply disturbed with hard rain and smoke.> microwave system also used repeater method for far relationship, where distance of therepeaters is 25 - 30 mile.> The system also not suitable to be used in urban because the wave may be mix with nextwave.





6.2 COMMUNICATION SYSTEM BASIC NEED

To enable occurrence of communication system, three basic points needed:

a) transmitter (Tx)b) recipient (Rx)

c) relationship media

TRANSMISSION AND ACCEPTANCE SIGNAL CONCEPT

There are two transmission and acceptance concept that commonly:

a) transmission line (guided)

Schedule 6.2 : Function delivery system block figure use transmission line schedule.

BLOCK FIGURE FUNCTION

source are made up human voice, music, telegraphsignal, information.

tranduser a device used to replace information signal toelectric power or otherwise

amplifier strengthen weak signal

transmission line delivery media linking transmitter and recipient

Amplifier amplifier

transmission line

Sourcetranduser

tranduser

destination

SENDER

RECIPIENT





c) radio channel (not guided)

Schedule 6.3 : Function of delivery system block figure using radio channel

BLOCK FIGURE FUNCTION

TRANSMITTER ANTENNA a metallic substance object / wire / a collection wires copethrough one design suitably to replace high frequency current

to electromagnetic waves form and further beamed.

Receiver antenna Be able to receive electromagnetic waves signal beamed, insome mWatt ( low power)

TERMS IN COMMUNICATION SYSTEM

a) Simplex

only allowed relationship occurring in one-way, example radio and tv.

WAVE

ELECTROMAGNET

Amplifier Amplifier

TRANSMITTER Receiving antenna

ANTENNA

Figure 6.5 : Delivery system block figure using radio channel.

Source tranduser tranduser

destination

A B

A B





b) duplex half

allow relationship occurring in bilateral, but in different time, example intercom and walkie-talkie

ketika

ketika

c) full duplex

allow bilateral relationship, in a time, example telephone system.

ELECTROMAGNETIC WAVES

Also known as radio waves, which account oscillations electric and magnetic field, moving invelocity of light, v=3X 108m / s. Radio waves can be generated in wide scope, and it may beclassed to certain frequency strips, which is known as spectrum frequency radio, imaginable

such as table below

FREQUENCY

A B

BA

A B

wavelength

Frequency

Figure 6.6 : Spectrum electromagnetic waves frequency

V

L

F

L

F

H

F

V

H

F

U

H

S

H

F

E

H

F

` INFRARED

M

F

KOMESTIK's

RADIANCE

SINAR

X

SINAR

GAMA

INFRA

UNGU





Schedule 6.4 : Frequency band utilities

Frequency band Frequency Utilities

very lowfrequency (VLF)

3-30KHz >10000m long distance telegraphybroadcasting, human hearing range.

low frequency(LF)

30-300KHz 10000-1000m point to point, aid to navigation

middlefrequency (MF)

300-3MHz 1000-100m AM radio's broadcasting, relationshipbetween aero plane to port.

high frequency(HF)

3-30MHz 100-10m bilateral radio communication, point topoint, * short waves freq

very highfrequency(VHF)

30-300MHz 10m-1m radio move, FM's broadcasting, TVtransmission, aero plane relationship

ultra highfrequency(UHF)

300MHz-1GHz 1m-10cm mobile phone, radar (military), tvbroadcasting,>100MHz- microwaves

super highfrequency(SHF)

3-30GHz 0.01-0.001m satelite communication, is microwavesfrequency, bilateral radiocommunication

extremely highfrequency(EHF)

30-300GHz <0.01m satelite communication, radar system

6.3 ANALOGUE AND DIGITAL WAVE

INTRODUCTION

If you are watching television or listening to radio, have you ever thought how signal form issend to us? Yeah, your answer is right, it was an analog waveform which represented inelectromagnetic waves form. Analog wave can be represented in various forms such as right

triangle, square, jagged etc.

Can be divided into two:

Analogue (Au)

> electronic signal which vary directly with information signal change.

> example : signal from microphone







DIFFERENCE BETWEEN ANALOG SIGNAL AND DIGITAL

SCHEDULE 6.5 : DIFFERENCES BETWEEN ANALOG SIGNAL AND DIGITAL

ANALOG DIGITAL

Constantly changing with time it changing is not proportionately with time

For every instantaneous value t, there are aninstantaneous value for analog signal

For certain times signal could not bedetermined, it will alter spontaneous from 0Vvice versa.

Having different values include all valuebetween minimum and maximum

Has only two voltage value, either 0 volts and1volts, or other its represent bit 1 and 0

6.4 RELATIONSHIPS BETWEEN FREQUENCY (f),WAVELENGTH, AND VELOCITY (v)

The information signals that sent are:

> sinus signal ( is basis signal in communication system)

> other signals (square, triangle, jagged etc)

There are 3 ways to plot the signal forms:

> amplitude (in voltage unit) against time (in moment unit, t)

> amplitude (in voltage unit) against time (in meter unit, m)

> amplitude ( in voltage unit) against time (in angle unit)





AMPLITUDES AGAINST TIME

details could be identified:

a) frequency

> number of complete cycle in 1 seconds.

> Hz's unit, KHz and further.

b) period

> time taken for 1 cycle complete

> second unit (s), ms, micros etc

c) amplitude

> maximum signal value

10

0 5 10

Ampl/V

Time/s

one

Figure 6.9 : Amplitude Wave Against Time

From the figure:

> period = 10s

> amplitude= 10V

> frequency=1/T=1/10=0.1Hz

to obtain frequency value (f):

F=1/T

T= time to 1 cycles complete.





AMPLITUDES AGAINST DISTANCE

Details can be identifieds:

a) wavelength

> distance taken to make one cycle complete.

> from figure, wavelength, = 10m

1

0 5 10 distance

wavelength

Ampl/v

FIGURE 6.10 : AMPLITUDE AGAINST DISTANCE

Generally;

velocity, v = distance x time

For signal information:

Velocity,v =period

wavelength

known that, f=1/T

so ,v=f

wave propagation velocity,v =3 x 108 m/s





AMPLITUDE AGAINST ANGLE

Details identified:

a) Rotation angles of an instantaneous value:

> Example in 0V's value, phase=1800 and 3600

> If there are 2 same waves, but in different phase, the phase difference between them areknown as phase difference, Φ.

10

0

1800 3600 angles ( 0 )

Am l/v

FIGURE 6.11 : GRAPH OF AMPLITUDE AGAINST

10

0 180 360

Angles ( 0 )

From figure: Φ = 180

0

– 90

0

=90

0

Am l/v

FIGURE 6.12: METHOD TO SEEK ANGLE FROM ANALOG WAVE

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6.0 Principles of Telecommunication[1]