1. INTRODUCTION TO PRINCIPLES OF COMMUNICATION ENGINEERING PART 1
LECTURE 1
INTRODUCTION TO PRINCIPLES OF COMMUNICATION ENGINEERING
PART 1

2. of COMMUNICATION SYSTEM?
WHAT DO YOU UNDERSTAND of
COMMUNICATION SYSTEM?

3. DEFINITIONS OF COMMUNICATIONS
Humans exchanging information
Machines exchanging information
Conveying thoughts, feelings, ideas, and facts
Sending and receiving information by electronic means

5. BARRIERS TO COMMUNICATIONS
Language: human, computer, or electronic
Distance: space between sending and receiving parties

6. 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

7. FORMS OF ELECTRONIC COMMUNICATIONS
Radio and TV broadcasting
Telephone, wired and wireless
Fax
Pagers
Computer networks: modem, , Internet and World Wide Web, wireless
Satellites, radar, radio telescopes

9. Communication systems

10. Basic components:  Transmitter  Channel or medium  Receiver
 Noise degrades or interferes with transmitted information.

11. 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.

12. 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).

13. 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

14. 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

15. Communication Systems
Noise
Noise is random, undesirable electronic energy that enters the communication system via the communicating medium and interferes with the transmitted message.

16. TYPES OF COMMUNICATIONSTX
Channel RX
Simplex:
One-way
Duplex:
Two-way
Half duplex:
Alternate TX/RX
Full duplex:
Simultaneous
TX/RX TX RX
Channel(s) TX RX

17. TYPES OF COMMUNICATIONS SIGNALS
Analog - smooth and continuous voltage variation.
Digital - binary or two voltage levels.
Time

18. 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.

19. Basic analog communications system
Baseband signal (electrical signal)
EM waves (modulated signal)
Transmitter
Input transducer
Transmission Channel
Modulator
EM waves (modulated signal)
Carrier
Baseband signal (electrical signal)
Receiver
Output transducer
Demodulator

20. 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.

21. Why modulation is needed?
To generate a modulated signal suited and compatible to the characteristics of the transmission channel.
For ease radiation and reduction of antenna size
Reduction of noise and interference
Channel assignment
Increase transmission speed

22. Modulation at the transmitter

23. AMPLITUDE MODULATION higher than the baseband frequency
The modulating (baseband) signal is a sinusoid in this example.
High-frequency carrier, normally much
higher than the baseband frequency

24. FREQUENCY MODULATION
The baseband signal controls the carrier’s frequency and the carrier’s amplitude remains constant.

25. FM Resting fc Increasing fc Decreasing fc Increasing fc Resting fc
Modulating signal
Carrier

26. 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.

27. MULTIPLEXING AND DEMULTIPLEXING
Single communications channel (radio or cable)
MUX
DEMUX
Recovered baseband
information signals
Original baseband
information signals

28. Modulation and Multiplexing

29. ELECTRONIC COMMUNICATIONS APPLICATIONS
Radio broadcasting (AM & FM)
Television broadcasting (analog & DTV)
Cable TV
Wireless remote control
Paging
Navigation and direction finding
Telemetry

30. ELECTRONIC COMMUNICATIONS APPLICATIONS (Continued)
Radio astronomy
Surveillance
RF identification (ID)
Music services
Telephones (wired, cordless, cellular)
Facsimile
Two-way radio

31. ELECTRONIC COMMUNICATIONS APPLICATIONS (Continued)
Radar
Sonar
Amateur radio
Citizens and family radio
Data communications
Networks
Internet and World Wide Web

32. 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.

33. PERIOD AND FREQUENCY COMPARED
T = One period
time
One cycle
Frequency = f = 1/T

34. Frequency and wavelength compared+ T
time
f = 1/T 
distance

35. CALCULATING WAVELENGTH AND FREQUENCY
 = wavelength in meters
f = frequency in MHz

36. THE ELECTROMAGNETIC SPECTRUM FROM 30 HZ TO 300 GHZ
Wavelength
( = 300/f)
107 m
106 m
105 m
104 m
103 m
102 m
10-1 m
10-2 m
10-3 m
10-4 m
10 m
1 m
Millimeter
waves
ELF VF
VLF LF MF HF
VHF
UHF
SHF
EHF
30 Hz
3 kHz
300 Hz
30 kHz
3 MHz
3 GHz
300 kHz
30 MHz
30 GHz
300 MHz
300 GHz
(f = 300/)
Frequency

37. LOW AND MEDIUM FREQUENCIES
Extremely Low Frequencies - 30 to 300 Hz
Voice Frequencies to 3000 Hz
Very Low Frequencies - 3 kHz to 30 kHz
Low Frequencies - 30 kHz to 300 kHz
Medium Frequencies kHz to 3 MHz

38. 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

39. THE ELECTROMAGNETIC SPECTRUM ABOVE 300 GHZ
Wavelength
0.8 x 10-6 m
0.4 x 10-6 m
10-3 m
10-4 m
10-5 m
Millimeter
waves
Ultraviolet
Infrared
X-rays
Visible
Gamma rays
Cosmic rays
300 GHz

40. OPTICAL FREQUENCIES Infrared - 0.7 to 10 micron
Visible light 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.

41. 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

42. Limitations in communication system
Physical constraint
-Delay, attenuation, bandwidth limitation, etc
Technological constraint
hardware.
Expertise
- economy, law

43. 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.

44. Frequency Spectrum &Bandwidth (cont’d)
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