Introduction to Communication Systems

2,083 views

Published on

Introduction to Communication Systems

Published in: Engineering, Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
2,083
On SlideShare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
Downloads
124
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Introduction to Communication Systems

  1. 1. Flexible · Affordable · Accessible the people’s university TEL 213/05 Telecommunication Principle Course Overview Semester January 2012
  2. 2. the people’s university Flexible · Affordable · Accessible Course Organization Unit Title Weeks Assessment 1 Introduction to Communication Systems 3 2 Principles of Digital Communication 3 Assignment #1 - 15% 3 Radio frequency communication systems, Microwave Devices and Antennas 4 Assignment #2 - 15% 4 Fixed Line Telephony, and Satellite Communication Systems 4 Assignment #3 – 20% 5 Computer Communication Networks & Internet 4 TOTAL 18
  3. 3. the people’s university Flexible · Affordable · Accessible Tutorial Classes Planning • Tutorial 1 • – 2 hours classroom • Tutorial 2 -2 hours classroom • (TMA 1 submission) • Tutorial 3 -2 hours classroom +3 Hours Lab • (TMA 2 submission) • Tutorial 4 – 2 hours classroom (TMA 3 +Lab Report submission) • Tutorial 5– 2 hours classroom
  4. 4. the people’s university Flexible · Affordable · Accessible Overall Assessment Type Marks Due Date TMA 1 15% Tutorial 2 TMA 2 15% Tutorial 3 TMA 3 15% Tutorial 4 Lab 5% Tutorial 4 Final Examination 50% After week 19 100%
  5. 5. the people’s university Flexible · Affordable · Accessible Tips for Effective Tutoring • Punctuality and attire • Telephone Tutoring • Internet Support • Encouraging students to ask questions and get to know them
  6. 6. the people’s university Flexible · Affordable · Accessible Self-Study • Six to seven hours per week – Averagely one hour a day • Suggested weekly reading and corresponding assignments – Please follow strictly the Course Guide, Table 1.0
  7. 7. the people’s university Flexible · Affordable · Accessible What to do when you have problems? • Contact your tutor immediately. • Do not delay in seeking help – if you straighten out a problem when you first identify it as a problem, you’ll be able to understand the work that comes later. • It’s rather like getting back on the right path after making a wrong turn. – The longer you delay, the harder it is to get back • Your tutor is there to help you to learn and to avoid frustrations in your learning.
  8. 8. Flexible · Affordable · Accessible the people’s university TEL 213/05 Telecommunication Principle Tutorial 1 Semester January 2012 Writer: Clarence Goh
  9. 9. the people’s university Flexible · Affordable · Accessible Welcome to Telecommunication Principle ! • Subject Code: TEL 213/05 • Class: • Tutor Name: ABC • Tutor Telephone: ABC • Contact Hours: ABC
  10. 10. the people’s university Flexible · Affordable · Accessible Welcome! • Tutorial 1
  11. 11. the people’s university Flexible · Affordable · Accessible Why are we learning this? • Everything we have today is based on telecommunications including: – Cell Phones – Television – The internet – Satellite
  12. 12. the people’s university Flexible · Affordable · Accessible 3 Main components of a communication system • Transmitter • Receiver • Transmission line Can you identify which is which from the picture above? Note: If the tin can acts as both a receiver and a transmitter, it is known as a transceiver
  13. 13. the people’s university Flexible · Affordable · Accessible Simplex/Half Duplex/Full Duplex • The following is a discussion on the THREE main types of transmission circuits (channels), simplex, half duplex and full duplex. • Simplex – Data in a simplex channel is always one way. Simplex channels are not often used because it is not possible to send back error or control signals to the transmit end. An example of a simplex channel in a computer system is the interface between the keyboard and the computer, in that key codes need only be sent one way from the keyboard to the computer system. • Half Duplex – A half duplex channel can send and receive, but not at the same time. Its like a one-lane bridge where two way traffic must give way in order to cross. Only one end transmits at a time, the other end receives. • Full Duplex – Data can travel in both directions simultaneously. There is no need to switch from transmit to receive mode like in half duplex. Its like a two lane bridge on a two-lane highway.
  14. 14. the people’s university Flexible · Affordable · Accessible Simplex System Example: Radio
  15. 15. the people’s university Flexible · Affordable · Accessible Half Duplex System Example: Walkie-talkie
  16. 16. the people’s university Flexible · Affordable · Accessible Full Duplex System Example: Telephone
  17. 17. the people’s university Flexible · Affordable · Accessible Definition • Baseband signal – original unmodulated signals • Broadband signals – modulated signals • Modulation - is the process of having baseband voice, video or digital signal modify another higher-frequency signal, the carrier to enable transmission at greater distance with less loss • Multiplexing – Process of “queuing” up signals for transmission.
  18. 18. the people’s university Flexible · Affordable · Accessible Modulation Why modulate? 1.Combines the signal with the carrier in a unique way. 2.Makes the signal less susceptible to noise. 3.Decreases the size of the antenna needed to transmit signals. 4.Increases the distance of transmission.
  19. 19. the people’s university Flexible · Affordable · Accessible Modulation • Modulation techniques are methods used to encode digital information in an analogue world. • There are three basic modulation techniques – AM (amplitude modulation) – FM (frequency modulation) – PM (phase modulation) • All 3 modulation techniques employ a carrier signal. A carrier signal is a single frequency that is used to carry the intelligence (data). – For digital, the intelligence is either a 1 or 0. – When we modulate the carrier , we are changing its characteristics to correspond to either a 1 or 0.
  20. 20. the people’s university Flexible · Affordable · Accessible Modulation
  21. 21. the people’s university Flexible · Affordable · Accessible Amplitude Modulation • Modifies the amplitude of the carrier to represent 1s or 0s – a 1 is represented by the presence of the carrier for a predefined period of 3 cycles of carrier. – Absence or no carrier indicates a 0 • Pros – Simple to design and implement • Cons – Noise spikes on transmission medium interfere with the carrier signal. – Loss of connection is read as 0s.
  22. 22. the people’s university Flexible · Affordable · Accessible Amplitude Modulation
  23. 23. the people’s university Flexible · Affordable · Accessible Amplitude Modulation
  24. 24. the people’s university Flexible · Affordable · Accessible Amplitude Modulation Equations
  25. 25. the people’s university Flexible · Affordable · Accessible AM and FM in TV Transmission • A terrestrial television signal is comprised of AM and FM. AM is used for video while FM, for video. • Modulation is a process of combining a high frequency, high amplitude signal (carrier) with an information signal to enable the modulated signal to be of high frequency, therefore enabling long distance transmission (and smaller antenna size)
  26. 26. the people’s university Flexible · Affordable · Accessible AM Equations
  27. 27. the people’s university Flexible · Affordable · Accessible Modulation Percentage • M=Vm/Vc • <1(undermodulation) • =1 (100% modulation) • >1 (overmodulation)
  28. 28. the people’s university Flexible · Affordable · Accessible Amplitude modulated waveform
  29. 29. the people’s university Flexible · Affordable · Accessible Frequency Response of AM signal
  30. 30. the people’s university Flexible · Affordable · Accessible Frequency Response of AM signal via Matlab Simulation
  31. 31. the people’s university Flexible · Affordable · Accessible Power Equations for AM
  32. 32. the people’s university Flexible · Affordable · Accessible Example 1 -AM Modulation Index and modulation percentage • Calculate the modulation index, m and percentage, M if the modulation voltage is given as 3V, while the carrier voltage is 6V. Conclude if the resultant modulated waveform is fully-modulated, under-modulated or over-modulated.
  33. 33. the people’s university Flexible · Affordable · Accessible AM Example 2 •Determine the total power, Pt of the AM DSB system. •What is the modulation factor, m? •Calculate the upper sideband frequency and the lower sideband frequency. •Calculate the bandwidth of this signal.
  34. 34. the people’s university Flexible · Affordable · Accessible Solution – example 2 - AM
  35. 35. the people’s university Flexible · Affordable · Accessible Solution – example 2 - AM
  36. 36. the people’s university Flexible · Affordable · Accessible Example 3 - AM • Calculate the modulation index, m if Vmax(p-p) is 5.9V and Vmin(p-p) is 1.2V.
  37. 37. the people’s university Flexible · Affordable · Accessible Frequency Modulation
  38. 38. the people’s university Flexible · Affordable · Accessible FM equation and FM in frequency spectrum
  39. 39. the people’s university Flexible · Affordable · Accessible Finding bandwidth using Bessel and Carson
  40. 40. the people’s university Flexible · Affordable · Accessible Example - FM
  41. 41. the people’s university Flexible · Affordable · Accessible Solution
  42. 42. the people’s university Flexible · Affordable · Accessible
  43. 43. the people’s university Flexible · Affordable · Accessible Definition of Wavelength
  44. 44. the people’s university Flexible · Affordable · Accessible Example - Wavelength • Calculate the wavelength if the frequencies of the following waves are given as below: • a. High-pitched sound wave (f=18kHz) • b. Radio wave (f=10MHz)
  45. 45. the people’s university Flexible · Affordable · Accessible Electromagnetic spectrum for communication
  46. 46. the people’s university Flexible · Affordable · Accessible Low Frequency usage • Extremely Low Frequencies (ELF) are in the 30Hz -300Hz range. These include ac power line frequencies (50 and 60Hz are common), as well as those frequencies in the low end of the human audio range. • • Voice Frequencies (VF) are in the range of 300 to 3000Hz. This is the normal range of human speech. Although human hearing extends from approximately 20 to 20000Hz, most intelligible sounds occur in the VF range. • • Very Low Frequencies (VLF) are in the range of 9kHz to 30kHz and include the higher end of the human hearing range up to about 15 to 20kHz. Many musical instruments make sounds in this range as well as in the ELF and VF ranges. The VLF range is also used in some government and military communication. For example, VLF radio transmission is used by the navy to communicate with submarines. • • Low Frequencies (LF) are in the 30-300kHz range. The primary communication services using this range are in aeronautical and marine navigation. Frequencies in this range are also used as subcarriers, signals that are modulated by the baseband information. Usually, two or more subcarriers are added, and the combination is used to modulate the final high-frequency carrier.
  47. 47. the people’s university Flexible · Affordable · Accessible Medium to High Frequency Usage • Medium Frequencies (MF) are in the 300 to 3000kHz (0.3MHz-3.0MHz) range. The major application of frequencies in this range is AM radio broadcasting (535 to 1605MHz). Other applications in this range are various marine and aeronautical communication. • • High Frequencies (HF) are in the 3 MHz to 30MHz range. These are the frequencies generally known as short waves. All kinds of simplex broadcasting and half-duplex two-way communication take place in this range. Broadcasts from BBC occur in this range. Government and military services use these frequencies for two-way communication. An example is diplomatic communication between embassies. Amateur radio and citizens band (CB) communication also occur in this part of the spectrum. • • Very High Frequencies (VHF) are in the 30MHz to 300MHz range. This popular frequency range is used by many services, including mobile radio, marine and aeronautical communication, FM radio broadcasting (88 to 108MHz) and TV channels (RTM channel 1, RTM channel 2 and channel 8). Radio amateurs also have numerous bands in this frequency range. • • Ultra High Frequencies (UHF) are in the 300 MHz to 3000MHz range. This includes UHF TV channels (such as TV3), and also for land mobile communication and services such as cellular telephones as well as for military communication. Some radar and navigation services occupy this portion of the frequency spectrum, and radio amateurs also have bands in this range.
  48. 48. the people’s university Flexible · Affordable · Accessible Microwaves, EHF and optical • Microwaves are in between 1000MHz (1GHz) and 30GHz. Microwave ovens usually operate at 2.45GHz. Superhigh frequencies (SHFs) are in the 3GHz to 30GHz range. These microwave frequencies are widely used for satellite communication and radar. Wireless local-area networks (LANs) also occupy this region. • • Extremely High Frequencies (EHF) are from 30GHz to 300GHz. Electromagnetic signals with frequencies higher than 30GHz are referred to as millimeter waves. Equipment used to generate and receive signals in this range is extremely complex and expensive but there is a growing use of this range for satellite communication and computer data. • • Frequencies between 300GHz and the Optical Spectrum. This portion of the spectrum is rarely used. It is a cross between RF and optical. Lack of hardware and components operating in this frequency range prevents its use.
  49. 49. the people’s university Flexible · Affordable · Accessible Telephone System
  50. 50. the people’s university Flexible · Affordable · Accessible The television signal
  51. 51. the people’s university Flexible · Affordable · Accessible AMPS Mobile Phone System
  52. 52. the people’s university Flexible · Affordable · Accessible Problem with AMPS
  53. 53. the people’s university Flexible · Affordable · Accessible New Mobile Telephone Switching Office (MTSO) Systems
  54. 54. the people’s university Flexible · Affordable · Accessible Multiple base stations connected to MSC and PSTN
  55. 55. the people’s university Flexible · Affordable · Accessible Example • An area has 7 clusters and each cluster has 7 cells. Calculate the number of RBS and the number of cells in the area. • Number of RBS = Number of clusters * Number of cells = 7*7=49 • Number of cells= Number of RBS = 49
  56. 56. the people’s university Flexible · Affordable · Accessible RBS, channels, cluster and cell
  57. 57. the people’s university Flexible · Affordable · Accessible Conventional versus cellular radio system Conventional System Cellular Radio System No frequency reuse Frequency reuse Used before 1980's Used after 1980's Low Capacity High frequency Interference to adjacent space areas High capacity High transmitted power No interference with adjacent cells High antenna height Low antenna height Equipment bulky Hand Portable
  58. 58. the people’s university Flexible · Affordable · Accessible Example • Calculate the number of Erlangs if a user were to remain in his/her cell, and makes 30 calls within an hour, with each call lasting for a duration of 2 minutes. • Minutes of traffic = number of calls * duration • =30*2=60 • Traffic Figure = 60/60=1 Erlang
  59. 59. the people’s university Flexible · Affordable · Accessible Thank you!

×