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 ra