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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
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

analog transmission outlines
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

5 1 modulation of digital data
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

5 1 modulation of digital signals cont
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 1 modulation of digital signals cont1
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

5 1 modulation of digital signals cont2
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

5 1 modulation of digital signals cont3
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

5 1 amplitude shift keying cont
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

5 1 modulation of digital data cont
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

5 1 modulation of digital data cont1
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

5 1 cont
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

5 1 frequency shifting keying fsk
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

5 1 fsk cont
5.1 FSK (cont.)
  • Bandwidth = Fc1 – Fc0 + Nbaud

From p. 121, Fig. 5.7, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 1 fsk cont1
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

5 1 phase shift keying psk
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

5 1 psk constellation
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

5 1 psk constellation cont
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

slide18

5.1 4 PSK Constellation (cont.)

From p. 123, Fig. 5.11 Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 1 8 psk constellation cont
5.1 8 PSK Constellation (cont.)

From p. 124, Fig. 5.12, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 1 bw of psk
5.1 BW of PSK
  • BW = Baud rate

From p. 124, Fig. 5.13 Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

slide21

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

time domain signal for 8 qam
Time Domain Signal for 8-QAM

From p. 126, Fig. 5.15, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

16 qam constellations
16-QAM Constellations

From p. 126, Fig. 5.16, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

bit baud comparison
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

bit baud comparison1
Bit/Baud Comparison

From p. 127, Fig. 5.17, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

table 5 1 bit and baud rate comparison
Table 5.1 Bit and Baud Rate Comparison

From p. 127, Table 5.1, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 2 telephone modems
5.2 Telephone Modems

Figure 5.18 Manchester Encoding,

From p. 129, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 2 telephone modems cont
5.2 Telephone Modems (cont.)

Figure 5.19, From p. 129, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 2 telephone modems cont1
5.2 Telephone Modems (cont.)

Figure 5.20, From p. 130, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 2 telephone modems cont2
5.2 Telephone Modems (cont.)

Figure 5.21, From p. 131, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 2 telephone modems cont3
5.2 Telephone Modems (cont.)

Figure 5.22, From p. 132, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont1
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont2
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont3
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont4
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont5
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont6
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont7
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

5 cont8
5 (cont.)

Figure 4.10 Manchester Encoding,

From p. 92, Data Communications and Networking, Forouzan, McGrawHill

5. Analog Transmisison - Lin

summary
Summary

Questions?

5. Analog Transmisison - Lin