Course Outcomes (CO) CO1: Ability to utilize software and
simulation tools in designing systems in communications. CO2:
Ability to analyze transmission of the signal through channels,
noise and modulation. CO3: Ability to identify, analyze and design
the architecture of radio frequency, amplifiers, mixers, AM and FM
modulators and demodulators, transmitter circuits and receiver
circuits. CO4: Ability to perform measurement, analyze output
signal and trouble shoot using laboratory equipments /
instruments.
Slide 4
SYNOPSIS OBJECTIVES: This subject introduces the students about
the design and electronics used in communication system. This
includes the design and architecture of radio frequency amplifiers,
mixers, AM and FM modulators and demodulators, transmitter circuits
and receivers circuits. It is also to give introduction to students
about how to analyze circuit and its importance in communication
electronic field.
Slide 5
SYNOPSIS TOPICS COVERED ARE: Introductions to Electronics
Communications, AM& SSB Modulations & AM Circuits, FM and
FM Circuits, Radio Transmitter and Communications Receivers
Transmission Lines
Slide 6
SYNOPSIS Practical: Designing and constructing of Radio
Frequency (RF) Receiver architecture, i.e. modulator, demodulator,
oscillator, filters, down converters, etc using software and
hardwares. Software : ADS 2009
Slide 7
ASSESSMENTS Final exam = 50% Test 1 & 2 = 20% Lab = 30% 5%
presentation 5% Report20% Project
Slide 8
List of text books and references [1] Louis E. Frenzel Jr,
Principles of Electronic Communication Systems, 3rd Ed., McGrawHill
2008. (text) [2] Wayne Tomasi, Electronics Communication Systems,
Prentice Hall [3] Paul Young, Electronics Communications
Techniques,
Slide 9
LECTURE 1 REVIEW TO COMMUNICATION SYSTEMS PART 1
Slide 10
WHAT DO YOU UNDERSTAND of COMMUNICATION SYSTEM?
Slide 11
DEFINITIONS OF COMMUNICATIONS Humans exchanging information
Machines exchanging information Conveying thoughts, feelings,
ideas, and facts Sending and receiving information by electronic
means
Slide 12
BARRIERS TO COMMUNICATIONS Language: human, computer, or
electronic Distance: space between sending and receiving
parties
Slide 13
COMMON FORMS OF COMMUNICATIONS Human voice: face-to-face
conversations, public speakers, actors in plays, etc. Audio: CDs,
tape, records, radio Body language: non-verbal Print: newspapers,
magazines, books, etc. Film: still and movie Video: movies,
graphics and animation Music: personal, concerts
Slide 14
FORMS OF ELECTRONIC COMMUNICATIONS Radio and TV broadcasting
Telephone, wired and wireless Fax Pagers Computer networks: modem,
e- mail, Internet and World Wide Web, wireless Satellites, radar,
radio telescopes
Slide 15
Slide 16
MODEL OF ALL COMMUNICATIONS SYSTEMS TXRX Noise Communications
medium Information to be transmitted Received information
Transmitter Receiver Channel
Slide 17
Model of all communication systems
Slide 18
Basic components: Transmitter Channel or medium Receiver Noise
degrades or interferes with transmitted information.
Slide 19
Communication Systems Transmitter The transmitter is a
collection of electronic components and circuits that converts the
electrical signal into a signal suitable for transmission over a
given medium. Transmitters are made up of oscillators, amplifiers,
tuned circuits and filters, modulators, frequency mixers, frequency
synthesizers, and other circuits.
Slide 20
Communication Systems Communication Channel The communication
channel is the medium by which the electronic signal is sent from
one place to another. Types of media include Electrical conductors
Optical media Free space System-specific media (e.g., water is the
medium for sonar).
Slide 21
Communication Systems Receivers A receiver is a collection of
electronic components and circuits that accepts the transmitted
message from the channel and converts it back into a form
understandable by humans. Receivers contain amplifiers,
oscillators, mixers, tuned circuits and filters, and a demodulator
or detector that recovers the original intelligence signal from the
modulated carrier
Slide 22
Communication Systems Transceivers A transceiver is an
electronic unit that incorporates circuits that both send and
receive signals. Examples are: Telephones Fax machines Handheld CB
radios Cell phones Computer modems
Slide 23
Communication Systems Noise Noise is random, undesirable
electronic energy that enters the communication system via the
communicating medium and interferes with the transmitted
message.
Slide 24
TYPES OF COMMUNICATIONS TXRX TX RX Simplex: One-way Duplex:
Two-way Half duplex: Alternate TX/RX Full duplex: Simultaneous
TX/RX Channel Channel(s)
Slide 25
TYPES OF COMMUNICATIONS SIGNALS Analog - smooth and continuous
voltage variation. Digital - binary or two voltage levels.
Time
Slide 26
COMMUNICATIONS SIGNAL VARIATIONS Baseband - The original
information signal such as audio, video, or computer data. Can be
analog or digital. Broadband - The baseband signal modulates or
modifies a carrier signal, which is usually a sine wave at a
frequency much higher than the baseband signal.
Slide 27
MODULATION An electronic technique in which a baseband
information signal modifies a carrier signal (usually a sine wave)
for the purpose of frequency translation and carrying the
information signal via radio. The common types of modulation are
amplitude, frequency and phase.
Slide 28
Modulation at the transmitter
Slide 29
AMPLITUDE MODULATION High-frequency carrier The modulating
(baseband) signal is a sinusoid in this example.
Slide 30
An AM signal as it usually appears on an oscilloscope The
carrier frequency is normally much higher than the baseband
frequency.
Slide 31
FREQUENCY MODULATION The baseband signal controls the carriers
frequency and the carriers amplitude remains constant.
Slide 32
Resting f c Increasing f c Decreasing f c Resting f c
Modulating signal Carrier FM
Slide 33
MULTIPLEXING Multiplexing (MUX or MPX) - the process of
simultaneously transmitting two or more baseband information
signals over a single communications channel. Demultiplexing (DEMUX
or DMPX) - the process of recovering the individual baseband
signals from the multiplexed signal.
Slide 34
MULTIPLEXING AND DEMULTIPLEXING MUXDEMUX Single communications
channel (radio or cable) Original baseband information signals
Recovered baseband information signals
Slide 35
Modulation and Multiplexing
Slide 36
Slide 37
ELECTRONIC COMMUNICATIONS APPLICATIONS Radio broadcasting (AM
& FM) Television broadcasting (analog & DTV) Cable TV
Wireless remote control Paging Navigation and direction finding
Telemetry
Slide 38
ELECTRONIC COMMUNICATIONS APPLICATIONS (Continued) Radio
astronomy Surveillance RF identification (ID) Music services
Telephones (wired, cordless, cellular) Facsimile Two-way radio
Slide 39
ELECTRONIC COMMUNICATIONS APPLICATIONS (Continued) Radar Sonar
Amateur radio Citizens and family radio Data communications
Networks Internet and World Wide Web
Slide 40
FREQUENCY AND WAVELENGTH Cycle - One complete occurrence of a
repeating wave (periodic signal) such as one positive and one
negative alternation of a sine wave. Frequency - the number of
cycles of a signal that occur in one second. Period - the time
distance between two similar points on a periodic wave. Wavelength
- the distance traveled by an electromagnetic (radio) wave during
one period.
Slide 41
One cycle time PERIOD AND FREQUENCY COMPARED Frequency = f =
1/T T = One period
Slide 42
+ 0time distance Frequency and wavelength compared f = 1/T
T
Slide 43
CALCULATING WAVELENGTH AND FREQUENCY = wavelength in meters f =
frequency in MHz = 300/f f = 300/
Slide 44
ELF 10 3 m 10 7 m 10 4 m10 5 m10 6 m10 m 1 m 10 -1 m10 -2 m10
-3 m10 -4 m 10 2 m 300 Hz 30 Hz 30 kHz 3 kHz 300 kHz30 MHz 3 MHz
300 MHz 3 GHz 300 GHz 30 GHz THE ELECTROMAGNETIC SPECTRUM FROM 30
HZ TO 300 GHZ UHFVHFHFMFLFVLF VF SHFEHF Frequency Wavelength
Millimeter waves ( = 300/f) (f = 300/ )
Slide 45
LOW AND MEDIUM FREQUENCIES Extremely Low Frequencies - 30 to
300 Hz Voice Frequencies - 300 to 3000 Hz Very Low Frequencies - 3
kHz to 30 kHz Low Frequencies - 30 kHz to 300 kHz Medium
Frequencies - 300 kHz to 3 MHz
Slide 46
HIGH FREQUENCIES High Frequencies - 3 MHz to 30 MHz Very High
Frequencies - 30 MHz to 300 MHz Ultra High Frequencies - 300 MHz to
3 GHz (1 GHz and above = microwaves) Super High Frequencies - 3 GHz
to 30 GHz Extremely High Frequencies - 30 GHz to 300 GHz
Slide 47
10 -3 m10 -4 m 300 GHz Millimeter waves THE ELECTROMAGNETIC
SPECTRUM ABOVE 300 GHZ Wavelength 0.8 x 10 -6 m 0.4 x 10 -6 m
Infrared Visible Ultraviolet X-rays Gamma raysCosmic rays 10 -5
m
Slide 48
OPTICAL FREQUENCIES Infrared - 0.7 to 10 micron Visible light -
0.4 to 0.8 micron Ultraviolet - Shorter than 0.4 micron Note: A
micron is one millionth of a meter. Light waves are measured and
expressed in wavelength rather than frequency.
Slide 49
Noise, interference and distortion Noise:unwanted signals that
coincide with the desired signals. Noise is random, undesirable
electric energy. Two type of noise:internal and external noise.
Internal noise: Caused by internal devices/components in the
circuits. External noise:noise that is generated outside the
circuit. Eg: atmospheric noise,solar noise, cosmic noise, man made
noise. Interference-one type of external noise Distortion: signal
being distorted
Slide 50
Limitations in communication system Physical constraint -Delay,
attenuation, bandwidth limitation, etc Technological constraint -
hardware. - Expertise - economy, law
Slide 51
Frequency Spectrum &Bandwidth The frequency spectrum of a
waveform consists of all frequencies contained in the waveform and
their amplitudes plotted in the frequency domain. The bandwidth of
a frequency spectrum is the range of of frequencies contained in
the spectrum.It is calculated by subtracting the lowest frequency
from the highest.
Slide 52
Frequency Spectrum &Bandwidth (contd) Bandwidth of the
information signal equals to the difference between the highest and
lowest frequency contained in the signal. Similarly, bandwidth of
communication channel is the difference between the highest and
lowest frequency that the channel allow to pass through it
Slide 53
At this stage you should be able to: Explain the functions of
the three main parts of an electronic communication system.
Describe the system used to classify different types of electronic
communication and list example of each type. Discuss the role of
modulation and multiplexing in facilitating signal
transmission.
