Comm introduction
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The document provides an overview of the topics that will be covered in the Communication Engineering course. It discusses the basic elements of a communication system including transmitters, receivers, channels and noise. It also covers electromagnetic waves, analog and digital signals and systems, modulation techniques, and the electromagnetic spectrum and frequency allocations.
Comm introduction
- 1. DAE 32603- Communication Engineering
- 2. Student will learn: The basic elements that related with a communication system Chapter 1: Introduction to Communication System Objective:
- 3. Introduction to signals, medium, analog systems and digital systems. Energy and Electromagnetic Waves . Electromagnetic Spectrums and Allocations. Simplex, Duplex and Half Duplex . Chapter 1: Introduction to Communication System Topics:
- 4. Chapter 1: Introduction to Communication System What is COMMUNICATION???
- 5. Communication: A basic process of exchanging information . To convey thoughts, ideas and feelings to one another . Through spoken words, body movements and facial expressions. Later, through written letters, news papers and books. Nowadays, through many electronic devices . Eg.: telephones, emails, sms, mms, video streaming etc. Definition:
- 6. Started before 3000 B.C . - Egyptians develop hieroglyphics . 1834 – Gauss & Weber build the electromagnetic telegraph. 1844 – S. F. B. Morse patent the telegraph. 1876 – A. G. Bell develops and patent telephone. 1895 – Marconi demonstrates wireless telegraphy . 1926 – Baird & Jenkins demonstrate the television . 1933 – E.H. Armstrong invents FM (Frequency Modulation). 1937 – A. Reeves conceives PCM(Pulse Code Modulation) . 1954 – Colour TV broadcasting begins. 1962 – First satellite communication. 1969 – Internet is invented. 1975s – PC(Personal Computer) come into use. 1981s – Modems become widespread. 1983 – First cellular telephone system become operational. 1989 – GPS is use for commercial and personal applications. 1989 – www is invented. 2000s – Era of digital signal processing. History of communication:
- 7. Transmitter (Tx) Noise Receiver (Rx) Communications channel or medium Human message input (voice, code, pictures, data, etc.) Message for human application Information source Destination Communication System: Chapter 1: Introduction to Communication System Figure 1.1 : The basic elements of communication system.
- 8. Collection of electronic devices or circuits that convert the information into a signal that is more suitable for transmission over a given transmission medium . Eg. Microphone or microwave radio transmitter. Transporting signal from the TX to the RX . Eg. Pair of wires that carry voice signal from a microphone to a headset. Transmitter: Chapter 1: Introduction to Communication System Medium:
- 9. Chapter 1: Introduction to Communication System Collection of electronic devices or circuits that accepts the transmitted signal from the transmission medium and converts them back to their original form . Eg. Earphone or complex electronic receiver. Random, undesired electrical energy that enters the communication system via the communication media (i.e. inserted between TX and RX) and interferes with the transmitted message. Noise: Receiver:
- 10. Figure 1.2 : Basic transmitter block diagram. Signal source Base band converter Modulation and power amplification Transmission (Electromagnetic Field) Subsystem synchronization Transmitter: Chapter 1: Introduction to Communication System
- 11. Figure 1.3 : Basic receiver block diagram. Receiver: Chapter 1: Introduction to Communication System Amplification and demodulation Base band inverter Synchronization system Base band processing Electromagnetic field
- 12. Electronic communication: Transmission, reception and processing of information between 2 or more locations using electronic circuit. Information: Analog or digital signal that had been converted to electromagnetic energy. Base band converter: To convert the signal source into base band waveform for the carrier signal before transmission . Analog or digital system. Subsystem synchronization: Synchronizing connection between the TX and RX for recovery processes . Terminology: Chapter 1: Introduction to Communication System
- 13. Transmission impairments : Any undesired effect on the signals while traveling from the transmitter to the receiver, such as noise, attenuation, interference and other losses caused by the atmosphere or the medium itself. Attenuation : Drop in signal power due to distance travel by the signal. Interference : Noise signal that has the same frequency as the information signal . Terminology: Chapter 1: Introduction to Communication System
- 14. Digital and Analog signal Chapter 1: Introduction to Communication System
- 15. Chapter 1: Introduction to Communication System Message signals can be in two forms: Analog signals Analog information source produces messages that defined on a continuum ( transition of one language to another) . Eg. Microphone. Digital signals Digital information source produces a finite set of possible messages. Eg. Telephone touchtone pad.
- 16. Signal with interference Chapter 1: Introduction to Communication System
- 17. Chapter 1: Introduction to Communication System DEK 3233 COMMUNICATION ENGINEERING Analog Signal: Components of Speech Characterized by data whose values vary over a continuous range. Frequency range (of hearing) 20 Hz-20 kHz . Speech 100Hz-7kHz . Easily converted into electromagnetic signal for transmission. Sound frequencies with varying volume converted into electromagnetic frequencies with varying voltage . Limit frequency range for voice channel ~ 300-3400Hz .
- 18. Chapter 1: Introduction to Communication System Digital Signal: From computer terminals etc. Constructed with finite number of symbols . Eg. Binary numbers, morse code, ASCII code etc. Bandwidth depends on data rate
- 19. Guided coaxial cable, twisted pair, fiber optic, waveguide. The medium is more important. Unguided wireless (terrestrial, spacewave, free space, earth wave). The bandwidth produced by the antenna is more important. Characteristics and quality determined by medium and signal. Key concerns are data rate and distance. Chapter 1: Introduction to Communication System Transmission Medium
- 20. Chapter 1: Introduction to Communication System Analog Communication System Analog communication system transfers information from an analog source to the intended receiver (sink). Both info and carrier are analog signals. Advantages: A Simple system Cheap Disadvantages: Noise Attenuation - high loss
- 21. Chapter 1: Introduction to Communication System Digital Communication System Digital communication system transfers information from an digital source to the sink. Original source info may be in digital or analog signal. If analog signal = convert to digital pulses prior to transmission & converted back to analog signal at the RX. Disadvantages: More BW required Synchronization required.
- 22. Advantages: Digital technology Low cost LSI/VLSI technology Data integrity Longer distances over lower quality lines Capacity utilization High bandwidth links economical High degree of multiplexing easier with digital techniques Security & Privacy Encryption Integration Can treat analog and digital data similarly Chapter 1: Introduction to Communication System
- 23. Chapter 1: Introduction to Communication System Energy and Electromagnetic Waves
- 24. Electronic communication system send info from Tx to Rx by sending electromagnetic energy . Modes: voltage, current, radio emission or light. Laws involved: Wavelength -the distance traveled in time to complete one cycle. Velocity – the speed at which energy travels through the medium. Frequency – the number of oscillation or cycle per second (hertz, Hz) v = ƒ Chapter 1: Introduction to Communication System
- 25. Radio wave, television wave, and microwaves are all types of electromagnetic waves . They differ from each other in wavelength . Wavelength is the distance between one wave crest to the next. Wave
- 26. Please refer to Maxwell’s Equation for more explanation. Chapter 1: Introduction to Communication System Electromagnetic Wave
- 27. Chapter 1: Introduction to Communication System
- 28. Chapter 1: Introduction to Communication System Electromagnetic Spectrum and Allocations
- 29. It refers to the total span of frequencies and corresponding wavelengths used in communication systems. 10,000 Hz to billions Hz. Application depends on the frequency allocation. Eg. Submarines, AM broadcast, TV, Cellular phones, satellite systems etc. Chapter 1: Introduction to Communication System Electromagnetic Spectrum
- 30. Chapter 1: Introduction to Communication System Electromagnetic Spectrum
- 31. Ultra High Frequency (UHF) * freq > 1GHz is known as microwave TV land mobile communication cellular phone military certain radar and navigation system microwave and satellite radio system amateur radio Chapter 1: Introduction to Communication System
- 32. Chapter 1: Introduction to Communication System Super High Frequency (SHF) microwave and satellite radio system radar specialized form of 2-way radio Extremely High Frequency (EHF) seldom used in radio communication except in very sophisticated, expensive and specialized application satellite communication Radar * freq > 300 GHz are not referred as radio wave
- 33. Infrared refers to electromagnetic radiation generally associated with heat anything that produced heat generate infrared signal eg : light bulb, human body astronomy (to detect stars) electronic photography heat-seeking guidance system (weapon) TV remote control Visible light optical communication Chapter 1: Introduction to Communication System
- 34. Bandwidth Portion of the electromagnetic spectrum occupied by the signal Frequency range over which a receiver or other electronic circuits operate. Difference between the upper and lower limit frequency , limits of the signal , or equipment operation range Channel bandwidth Range of frequencies required to transmit the desired information i.e. an audio signal (3kHz) being modulated by a 1000kHz carrier signal using AM modulation Chapter 1: Introduction to Communication System Bandwidth(BW) and Channel BW
- 35. Chapter 1: Introduction to Communication System
- 36. Example 1: What is the bandwidth of HF signal? Chapter 1: Introduction to Communication System
- 37. Example 2: How many times more BW does the UHF band have than the VHF band? Chapter 1: Introduction to Communication System
- 38. Shannon’s Law: I = 3.32BW log 10 (1 + (S/N)) I= information capacity, Unit: bits/second C = information or channel capacity BW = bandwidth (kHZ) S = signal power (W) N = noise power (W) Chapter 1: Introduction to Communication System Information Capacity
- 39. Example 3: Q. For a standard telephone circuit with signal-to-noise power ratio of 1000(30dB) and a bandwidth of 2.7kHz, determine the Shannon limit for information capacity A. 26.9 kbps Chapter 1: Introduction to Communication System
- 40. Gain and attenuation often expressed in decibels, rather than ratio value (decimal) Decibel, dB unit of measurement originally created as a way of expressing the hearing response of human ear to various sound levels . A decibel is one-tenth of a bel . Using decibel, total gain or attenuation can be calculated by simply adding the gains and the attenuation expressed in decibel. Chapter 1: Introduction to Communication System Decibel
- 41. Beside performing ratio operation, decibel is also used to expressed power in communication . A notation is added after the dB symbol, dBW, dBm etc. For dBm , reference level = 1mW . A larger unit, dBW has reference value of 1W . dBm and dBW are decibel units used for expressing power in communication. Chapter 1: Introduction to Communication System
- 42. Chapter 1: Introduction to Communication System Simplex, Duplex and Half Duplex
- 43. a) Simplex is one direction data communication. e.g radio… Communication is only from one direction. b) Half Duplex is involving two directions but only one direction is allowed at a time. c) Duplex is two direction communication . Chapter 1: Introduction to Communication System
- 44. Chapter 1: Introduction to Communication System
- 45. Quiz: Gives 2 examples of each data communication: Simplex Duplex Half Duplex Chapter 1: Introduction to Communication System
- 46. The end Chapter 1: Introduction to Communication System