Intro to Electronic Communication System

7/31/2019 Intro to Electronic Communication System

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INTRODUCTION TOELECTRONIC

COMMUNICATION SYSTEMS

Prepared by:

Engr. Analene M. Nagayo


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COMMUNICATION SYSTEMS

COMMUNICATION- is a basic process of exchanging information.

HUMAN COMMUNICATION

- conveying ones ideas, thoughts and feelings

to others.

Barriers : LANGUAGE & DISTANCE

ELECTRONIC COMMUNICATION refers to transmission, reception and

processing information using electronic circuit.

ELECTRONIC COMMUNICATION SYSTEM

collection of electronics circuit capable of

transmitting and/or receiving information by

electric means.


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BLOCK DIAGRAM OF A

COMMUNICATION SYSTEM

InformationSource

TransmitterChannel /

(communicationmedium)

ReceiverUser of

Information

message

signal

transmittedsignal

receivedsignal

Estimate ofmessage

signal

Noise

ELEMENTS OF A COMMUNICATION SYSTEM

INFORMATION SOURCE - responsible for the generation of message signals that

needs to be delivered to their destination. It may be coming from an analog or digital

source so that intelligence signal may be either analog or digital.

INFORMATION SOURCE MESSAGE SIGNAL

HUMAN AUDIO SIGNAL

COMPUTER BINARY DATA

VIDEO CAMERA/RECORDER VIDEO SIGNAL/PICTURES

FACSIMILE IMAGE DATA


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TRANSMITTER-collection of electronic components and circuits designed to transform the message

signal produced by the information source into a form suitable for transmission over a

given communication channel.

-Components of a transmittter are amplifiers, modulator, oscillator and antenna

BLOCK DIAGRAM OF A


COMMUNICATION CHANNEL

- medium by which the electronic signal is sent from one place to another.

- means of transporting signals between a transmitter and receiver.

-Attenuates information signal and causes the received signal to appear much lower in

amplitude

Types:

Unguided media for wireless communication- free space

Guided media for wire communication- fiber optic cable, twisted copper wire

& coaxial cable


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BLOCK DIAGRAM OF A

COMMUNICATION SYSTEMRECEIVER

-collection of electronic components and circuits that receives the transmitted message

from the channel and convert it back into a form understandable by the user of

information.

-Components of a receiver are amplifiers, demodulator and antenna

USER OF INFORMATION

- human or computer that needs the information sent by the source.

NOISE

- any unwanted form of energy that enters the communication system tending to

interfere with the proper and easy reception and reproduction of the transmitted signal.

examples:

Atmospheric noise static

Thermal Agitation noise


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LIMITATION OF A

COMMUNICATION SYSTEM NOISE

BANDWIDTH

- portion of electromagnetic spectrum occupied by a signal.

- frequency range over information signal is transmitted or over which a

receiver or other electronic circuit operates.

BW = f upper limit f lower limit

Information Capacity a measure of how much source information

can be carried through the system in a given period of time.

Hartleys Law states that the information capacity is directly

proportional of the bandwidth and transmission line.

Information capacity Bandwidth x Transmission Line


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CLASSIFICATIONS OF ELECTRONIC


I. ACCORDING TO THE MODE OF TRANSMISSION

(A) SIMPLEX COMMUNICATION SYSTEM

- One-way communication system

- It transmits signals only or receives signals only.- examples: pager, AM/FM radio, TV, wireless remote control

(B)DUPLEX COMMUNICATION SYSTEM

- Two-way communication system

a) HALF-DUPLEX COMMUNICATION SYSTEM

- Transmission and reception of signals non-simultaneously.

- example: portable two-way radio, radar, sonar

b)FULL-DUPLEX COMMUNICATION SYSTEM

- Transmission and reception of signals simultaneously.

- example: telephone system, data communication, LAN


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II. ACCORDING TO TYPES OF TRANSMITTED SIGNAL

(A)ANALOG COMMUNICATION SYSTEM

-Transmission and/or reception of analog

signals/continuous waves.- examples: AM/FM radio, Television

(B)DIGITAL COMMUNICATION SYSTEM

- Transmission and/or reception of digitalsignals/binary data.

- examples: Data communication systems:

LAN & WAN


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III. ACCORDING TO FORMS OF SIGNAL

(A)BASEBAND COMMUNICATION SYSTEM

-Transmission baseband signals directly over

the communication medium.

-Baseband signals are analog/digital signals

in their original form.

- example: telephone

(B)BROADBAND COMMUNICATION SYSTEM

- Works with modulated signals.-Modulated signals are signals in their

altered form.

-Modulation is a process of imposing low

frequency baseband signal onto a higher frequency

signal to allow effective transmission and

reception of the desired signal.


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ELECTROMAGNETIC WAVES


Information needed to be transmitted through free space for long-distance communication is

converted into signals that radiates through space.

- Are signals made-up of electric and magnetic fields that radiates through space

- Also called as radio waves

- Electromagnetic waves vary sinusoidally and it can be characterized by:

FREQUENCY , f

- is the number of voltage polarity alteration or electromagnetic field oscillation

that occurs in one second.

- Unit : cycles/sec (cps) or Hertz (Hz)

- Each alteration or oscillation is called cycle.

-f = 1/T

-WAVELENGTH,l

- is the distance travelled by an electromagnetic wave during the time of one

cycle.

- Length that one cycle of an electromagnetic wave occupies in space.

- Unit : meters(m) or miles (mi).

- Electromagnetic waves travel at a speed of light, c = 3 x 108 m/s or 1.86 x 105

mi/s.- l= kc / f where k is the velocity constant (k = 1 for free space)


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Examples:

1. If 5000 cycles takes place in 1 second, the frequency is

_________Hz.

Answer : 5KHz

2. If 1 cycle occurs 2ms, the frequency is __________Hz.

Answer : 500 Hz3. A radio signal with frequency of 1.5GHz has a wavelength

of ____m.

Answer : 0.2 m

4. A radio signal with wavelength of 2 miles has a frequencyof ____Hz.

Answer : 93KHz


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MODES OF ELECTROMAGNETIC WAVE PROPAGATION

Electromagnetic waves / radio waves normally travels in a straight line but this can be

changed by various method.

1. REFLECTION

- occurs when radio waves strike a boundary of two media an some or all of the

waves do not enter the second material. The waves that do not enter thesecond medium are reflected.

2. REFRACTION

- occurs when radio waves travel across the boundary of zones with different

characteristics.

- change in the direction of a ray as it passes obliquely from one medium to

another with different velocities of propagation.3. DIFFRACTION

- scattering of radio signals.

- occurs when radio waves move around bends or obstacles, thereby,

producing secondary wavelets.


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ELECTROMAGNETIC SPECTRUM


- Range of frequencies over which electronic communication takes place.

NAME FREQ. (Hz) (m) APPLICATION

ELF(EXTREMELY LOW

FREQ.)

30 300 107 - 106 AC power line (50 60 Hz) Low end of human hearing frequency (20

20KHz)

VF(VOICE FREQUENCY)

300 - 3000 106 105 Normal range of human speech (300 -3.4KHz)

Mid-part of human hearing frequency

VLF(VERY LOW

FREQUENCY)

3000 30K 105 104 High end of human hearing frequency Government and Military communication

systems

Most musical instruments

LF(LOW FREQUENCY)

30K 300K 104 103 SUBCARRIER freq. for modulation Aeronautical and Marine Navigational

system


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MF(MEDIUM FREQUENCY)

300K 3M 103 102 AM radio broadcasting (535 1605KHz)Other Aeronautical and Marine Navigational

system

HF(HIGH FREQUENCY)

3M 30M 102 101 Shortwave (SW) radio broadcastingTwo-way (CB & amateur) radio communication

VHF(VERY HIGH

FREQUENCY)

30M 300M 10 1 FM radio broadcasting (88 108MHz)TV ( CH2 CH13 ) broadcasting (54 216MHz)

Amatuer radio communication

UHF(ULTRA HIGH

FREQUENCY)

300M 3G 1 10-1 UHF (channel 14 to 83) TV broadcasting (470-890MHz)

Above 1 GHz is called microwave frequencies.

Cellular radio system (800 900 MHz)Amatuer radio communication

SHF(SUPER HIGH

FREQUENCY)

3G 30G 10-1 10-2 Microwave frequencies used for Satellite andRADAR



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EHF(EXTREMELY HIGH

FREQUENCY)

30G 300G 10-2 10-3 Satellite communication and specialized RADARsystem

INFRARED 0.7m 10m Infrared electromagnetic signal produced by heatsources

Radio Astronomy

Optical devices

Guidance in weapon system

TV remote control unit

LIGHT / VISIBLE 0.4m 0.8m Fiber Optic CommunicationLASER

Advantage of light wave signals is their high

frequency that gives them the ability to handle

tremendous amount of information.


ITU (International Telecommunication Union) an organization that bring togethervarious countries to discuss how frequency spectrum is to be divided up and shared.

National Telecommunication Commission (NTC) regulates the use of frequency

spectrum and controls all telephone and radio communication in the Philippines.


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Examples:

1. What is the bandwidth of voice frequencies ?Answer : BW = 3.4KHz - 300Hz = 3.1KHz

2. Why not assign 2KHz bandwidth for FM broadcast instead of the usual 200KHz

bandwidth?

Answer : due to the need of a wider bandwidth to carry information.

3. A signal occupies the spectrum space from 1.25G to 2.45GHz. The bandwidth is

_______.Answer: 1.2GHz


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REFERENCES Electronic Communication Systems Through

Advanced by W. Tomasi

Communication Electronics by L. Frenzel Lecture Notes in Principles of Communication by

A.H. Ballado and M.M. Sejera

Electronic Communication Systems by

G. Kennedy

Intro to Electronic Communication System

Documents

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