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Introduction in Telecommunication (121009) Chris Roeloffzen

Introduction in Telecommunication (121009) Chris Roeloffzen. Chair: Telecommunication engineering (EWI) Floor 8 HOGEKAMP EL/TN building (north) Telephone 489 2804 E-mail: c.g.h.roeloffzen@el.utwente.nl. Contents of the course. Book: Electronic Communications Systems

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Introduction in Telecommunication (121009) Chris Roeloffzen

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  1. Introduction in Telecommunication(121009) Chris Roeloffzen Chair: Telecommunication engineering (EWI) Floor 8 HOGEKAMP EL/TN building (north) Telephone 489 2804 E-mail: c.g.h.roeloffzen@el.utwente.nl

  2. Contents of the course Book: Electronic Communications Systems W. Tomasi. Prentice Hall, 5th edition, 2004 ISBN: 0-13-049492-5 For up-to-date information see: www.el.utwente.nl/tel/education/

  3. Contents of the course Lecture 1 - 3: Introduction Chapter 1: Introduction to Electronic Communications Chapter 2: Signal Analysis and Mixing Lecture 4 - 7: CW modulation Chapter 4: Amplitude modulation, Transmission Chapter 5: Amplitude modulation, Reception Chapter 6: Single-side banded Communication Systems Chapter 7: Angle Modulation Transmission Chapter 8: Angle Modulation Receivers Lecture 8 - 11: Media Chapter 12: Metallic Transmission Lines Chapter 14: Electromagnetic Wave Propagation Chapter 15: Antennas Chapter 13: Optical Fibers Lecture 12 - 14: Digital Communication Chapter 9: Digital Modulation Chapter 10: Digital Transmission Lecture 15 & 16: ????????????????? For specific information see: www.el.utwente.nl/te/education/education.htm

  4. Today: Lecture 1 Chapter 1: Introduction to Electronic Communications

  5. Chapter 1 • What is Telecommunication? • Transmission and Networks • Milestones • Signal transmission and Media • Modulation and Demodulation • The Electromagnetic Frequency Spectrum • Bandwidth and Information Capacity • Noise Analysis

  6. Introduction What is Telecommunication ?????? Any transmission, emission, or reception of signs, signals, writing, images and sound or intelligence of any nature by wire, radio, optical or other electromagnetic systems. ITU-1989 What are the three main components in a communication system? Give some information signals

  7. Communication Networks Point to point Mesh network

  8. Milestones Samuel Morse: 1837 telegraph

  9. Milestones Samuel Morse: 1837 telegraph Alexander Bell:1876 telephone

  10. Milestones Samuel Morse: 1837 telegraph Alexander Bell:1876 telephone Marconi: 1895 wireless telegraph not the inventor of Radio Nikola Tesla <1895: Inventor of Radio

  11. Milestones Samuel Morse: 1837 telegraph Alexander Bell:1876 telephone Marconi: 1895 wireless telegraph not the inventor of Radio Nikola Tesla <1895: Inventor of Radio Lee De Forest 1907: triode vacuum tube ‘Audion’ (amplifier)

  12. Milestones Samuel Morse: 1837 telegraph Alexander Bell:1876 telephone Marconi: 1895 wireless telegraph not the inventor of Radio Nikola Tesla <1895: Inventor of Radio Lee De Forest 1907: triode vacuum tube 1920: Commercial AM radio broadcast

  13. Milestones Samuel Morse: 1837 telegraph Alexander Bell:1876 telephone Marconi: 1895 wireless telegraph not the inventor of Radio Nikola Tesla <1895: Inventor of Radio Lee De Forest 1907: triode vacuum tube 1920: Commercial AM radio broadcast 1939: First FM radio broadcast ‘Alphine New Jersey by Edwin Armstrong

  14. Power Measurements (dB, dBm) Pin Pout I V R What is the advantage of using dB ????????????????

  15. Power Measurements (dB, dBm) Pin Pout

  16. Signal transmission (1) System noise and interference Transmitter Transmission mediumor Communications channel Receiver Copper cable (coax, UTP) Optical fiber cable Free space (Radio) Received Information Information source (intelligence)

  17. Signal transmission (2) Low-frequency source information (analog or digital) Transmission medium (channel) Modulator and frequency up-converter Power amplifier Amplifier Frequency down-converter Filter High-frequency oscillator High-frequency local oscillator Receiver Transmitter

  18. Transmission media and products

  19. Adaptation to the media Reasons are a.o. Necessity: transmission frequency range Efficiency: multiplexing Quality: e.g. due to noise, interference Example: Microwave transmission of AM Radio 500 kHz power power frequency frequency Modulation

  20. Modulation principle Change parameters of a carrier Information signal: Ac(t) fc(t) (t) Ac(t) : amplitude modulation AM ASK fc(t) : frequency modulation FM FSK (t) : phase modulation PM PSK Ac(t) and (t)  QAM (Digital) Analog Digital

  21. Demodulation principle Recovering of information signal from the received modulated transmission signal Example: AM: transmitted signal Demodulation: multiply with in the receiver

  22. Electromagnetic Frequency Spectrum Frequency : f [Hertz] Wavelength:  [m] c : velocity of light: 3 108 m/sec f  1 kHz  3 105 m 100 kHz  3 103 m 10 MHz  3 101 m = 30 m 1 GHz  3 10-1 m = 30 cm

  23. Electromagnetic Frequency Spectrum

  24. Bandwidth and information capacity (1) Hartleys law 1920 I = amount of information B = system bandwidth (Hertz) t = transmission time (seconds) The book is wrong!!!!!!

  25. Bandwidth and information capacity (2) Shannon limit for information capacity I = information capacity (bits per second) B = system bandwidth (Hertz) S/N = signal-to-noise power ratio (dimensionless)

  26. Bandwidth and information capacity Example: Standard telephony B = 2,7 kHz

  27. Bandwidth and information capacity Example: Standard telephony B = 2,7 kHz

  28. Noise S/N = signal-to-noise power ratio (dimensionless) With a given bandwidth a system has a larger capacity if the S/N ratio is larger In a practical system noise is always present Noise - internal (generated within the device) - external (generated outside the device)

  29. Noise Correlated noise: Related to signal Uncorrelated noise: Not related to signal

  30. Noise Correlated noise Nonlinear distortion Harmonic distortion Intermodulation distortion Uncorrelated noise External Atmospheric Extraterrestrial Solar Cosmic Man-made Impulse Interference Internal Thermal noise (random movement of electrons) Shot (random arrival of carriers) Transient time

  31. Thermal Noise (white noise) • Random • Continuous spectral density • Additive • Present in all devices N = noise power (watts) B = bandwidth (hertz) K = Boltzmann’s proportionality constant (1.38 10-23 Joules per kelvin) T = absolute temperature (kelvin)

  32. Noise voltage

  33. Signal-to-Noise Ratio Ps = signal power (watts) Pn = noise power (watts) Or expressed in decibel

  34. Noise in Amplifier Ideal amplifier Ap Nonideal amplifier Ap, Nd

  35. Noise Factor and Noise Figure F = noise factor (no dimension) NF = noise figure (dB)

  36. Noise Factor and Noise Figure of Cascade FT = total noise factor (dimensionless) NFT = total noise figure (dB)

  37. Noise Factor and Noise Figure of Cascade FT = total noise factor (dimensionless) NFT = total noise figure (dB)

  38. Noise Temperature T = environmental temperature (290 Kelvin) N = noise power (watts) K = Boltzmann’s constant (1.38 10-23 J/K) B = total noise factor (hertz) Te= equivalent noise temperature T= environmental temperature (290 Kelvin) F = noise factor (dimensionless)

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