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CPET/ECET 355

CPET/ECET 355. 5. Analog Transmission Data Communications and Networking Fall 2004 Professor Paul I-Hai Lin Electrical and Computer Engineering Technology Indiana University-Purdue University Fort Wayne www.ecet.ipfw.edu/~lin. Analog Transmission - Outlines. Modulation of Digital Data

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CPET/ECET 355

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  1. CPET/ECET 355 5. Analog Transmission Data Communications and Networking Fall 2004 Professor Paul I-Hai Lin Electrical and Computer Engineering Technology Indiana University-Purdue University Fort Wayne www.ecet.ipfw.edu/~lin 5. Analog Transmisison - Lin

  2. Analog Transmission - Outlines • Modulation of Digital Data • Bit rate and Baud rate • Carrier signal • Amplitude Shift Keying (ASK) • Frequency Shift Keying (FSK) • Phase Shift Keying (PSK) • Quadrature Amplitude Modulation (QAM) • Telephone Modems • Modem Standards: V.32, V.32bis, V.34bis, V.90, V.92 • Modulation of Analog Signals: AM, FM, PM 5. Analog Transmisison - Lin

  3. 5.1 Modulation of Digital Data • Modulation: converting binary data to analog signals From p. 116, Figure 5.1 of Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  4. 5.1 Modulation of Digital Signals (cont.) • Four Modulation Methods • Amplitude Shift Keying • Frequency Shift Keying • Phase Shift Keying • Quadrature Amplitude Modulation From p. 116, Figure 5.2 of Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  5. 5.1 Modulation of Digital Signals (cont.) • Bit rate • No. of bits transmitted per second • Baud rate • No. of signal units per second that are required to represent those bits • Baud rate is less than or equal to the bit rate • Example 1 • Question: An analog signal carries 4-bit in each signal unit. If 1000 signal units are sent per second, find the baud rate and the bit rate • Answer: • Baud rate = number of signal units per second = 1000 bauds/sec • Bit rate = baud rate x No. of bits per signal unit = 4000 bps 5. Analog Transmisison - Lin

  6. 5.1 Modulation of Digital Signals (cont.) • Example 2 • Question: The bit rate of a signal is 9600. If each signal unit carries 8-bits, what is the baud rate? • Answer: • Baud rate = number of signal units per second = 1000 bauds/sec, or • Baud rate = bit rate/no. of bits per signal unit = 9600/8 = 1200 bauds 5. Analog Transmisison - Lin

  7. 5.1 Modulation of Digital Signals (cont.) • Carries Signal • A high frequency signal that acts as a basis for the information signal • Digital information modulates the carrier signal by modifying one or more of its characteristics: Amplitude, Frequency, or Phase 5. Analog Transmisison - Lin

  8. 5.1 Amplitude Shift Keying (cont.) • Frequency & Phase remains constant • 1 – higher magnitude • 0 – smaller magnitude • Disadvantage – noise interference From p. 118, Figure 5.3 of Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  9. 5.1 Modulation of Digital Data(cont.) • Bandwidth of ASK • BW = (1 +d) * Nbaud • Where d: modulation factor, Nbaud = baud rate • If d = 0, BW = Nbaud • Bit rate = baud rate From p. 119, Figure 5.4 of Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  10. 5.1 Modulation of Digital Data(cont.) • Example 3 • Find the min BW for an ASK signal transmitting at 2000 bps. The transmission mode is half-duplex. • Ans: BW = Nbaud = 2000 Hz • Example 4 • Given a bandwidth of 5000 Hz for an ASK signal, what are the baud rate and bit rate? • Ans: In ASK, Bit rate = Baud rate = 5000 bps 5. Analog Transmisison - Lin

  11. 5.1 (cont.) • Example 5 • Given a BW of 10,000 Hz (1000 to 11,000 Hz), draw the full-duplex ASK diagram of the system. Find the carriers and the BWs in each direction. Assume there is no gap between bands in the two directions. • Ans: • BW = 10,000/2 = 5000 Hz • Carrier Frequency 1 = 1000 + 5000/2 = 3500 Hz • Carrier Frequency 2 = 11000 – 5000/2 = 8500Hz From p. 119, Fig 5.5, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  12. 5.1 Frequency Shifting Keying (FSK) • Varying frequency of carrier signal to represent 1 or 0 • Amplitude and phase remain constant From p. 120, Fig 5.6, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  13. 5.1 FSK (cont.) • Bandwidth = Fc1 – Fc0 + Nbaud From p. 121, Fig. 5.7, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  14. 5.1 FSK (cont.) • Example 6: Find the min BW for an FSK signal transmitting at 2000 bps. Transmission is in half-duplex mode, and the carriers are separated by 3000 Hz. • Ans: BW = Nbaud + Fc1 – Fc0 = 2000 + 3000 = 5000 Hz • Example 7: Find the maximum bit rates for an FSK signal if the BW of the medium is 12kHz and difference between the two carriers is 2000 Hz. Transmission is in full-duplex mode. • Ans: BW = baud rate + Fc1 – Fc0 Baud rate – BW – (Fc1 – Fc0) = 6000 – 2000 = 4000 bps 5. Analog Transmisison - Lin

  15. 5.1 Phase Shift Keying (PSK) • Varying phase of the carrier to represent 1 or 0 • 0 degree = 0, 180 degree = 1 From p. 121, Fig 5.8, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  16. 5.1 PSK Constellation • Not susceptible to the noise degradation (ASK) • No bandwidth limitation (FSK) • 1 –bit: two variations (0 and 180) From p. 122, Fig. 5-9, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  17. 5.1 PSK Constellation (cont.) • The 4 PSK or Q-PSK method • 2-bit variation of 4 phases: 00 – 0 deg.; 01 – 90 deg.; 10 – 180 deg.; 11 – 270 deg. From p. 123, Fig. 5.10, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  18. 5.1 4 PSK Constellation (cont.) From p. 123, Fig. 5.11 Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  19. 5.1 8 PSK Constellation (cont.) From p. 124, Fig. 5.12, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  20. 5.1 BW of PSK • BW = Baud rate From p. 124, Fig. 5.13 Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  21. 5.1 Quadrature Amplitude. Modulation • QAM - combining both ASK and PSK; same BW as ASK or PSK • 4-QAM – 1 amplitude, 4 phases; 8-QAM – 2 amplitude, 4 phases From p. 125, Fig. 5.14, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  22. Time Domain Signal for 8-QAM From p. 126, Fig. 5.15, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  23. 16-QAM Constellations From p. 126, Fig. 5.16, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  24. Bit/Baud Comparison • FSK • If over voice-grade line with 1200 bps • Requires 1200 signal units to send 1200 bits: 1200 baud • 8-QAM • 3-bit signal units • Bit rate: 1200 bps • Baud rate: 400 bauds 5. Analog Transmisison - Lin

  25. Bit/Baud Comparison From p. 127, Fig. 5.17, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  26. Table 5.1 Bit and Baud Rate Comparison From p. 127, Table 5.1, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  27. 5.2 Telephone Modems Figure 5.18 Manchester Encoding, From p. 129, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  28. 5.2 Telephone Modems (cont.) Figure 5.19, From p. 129, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  29. 5.2 Telephone Modems (cont.) Figure 5.20, From p. 130, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  30. 5.2 Telephone Modems (cont.) Figure 5.21, From p. 131, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  31. 5.2 Telephone Modems (cont.) Figure 5.22, From p. 132, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  32. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  33. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  34. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  35. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  36. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  37. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  38. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  39. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  40. 5 (cont.) Figure 4.10 Manchester Encoding, From p. 92, Data Communications and Networking, Forouzan, McGrawHill 5. Analog Transmisison - Lin

  41. Summary Questions? 5. Analog Transmisison - Lin

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