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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 SYSTEM
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
COMMUNICATION SYSTEM
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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CLASSIFICATIONS OF ELECTRONIC
COMMUNICATION SYSTEM
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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CLASSIFICATIONS OF ELECTRONIC
COMMUNICATION SYSTEM
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
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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ELECTROMAGNETIC WAVES
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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ELECTROMAGNETIC WAVES
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
ELECTROMAGNETIC WAVES
- 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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NAME FREQ. (Hz) (m) APPLICATION
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
ELECTROMAGNETIC WAVES
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NAME FREQ. (Hz) (m) APPLICATION
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.
ELECTROMAGNETIC WAVES
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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ELECTROMAGNETIC WAVES
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