Module 4
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This document discusses various methods for analog transmission including digital-to-analog conversion and analog-to-analog modulation. Digital-to-analog conversion involves changing characteristics of an analog signal based on digital data. Methods covered include amplitude shift keying, frequency shift keying, phase shift keying, and quadrature amplitude modulation. Analog-to-analog modulation involves representing analog information with an analog signal. Types discussed are amplitude modulation, frequency modulation, and phase modulation. Modulation is needed if the transmission medium is bandpass in nature or only a bandpass channel is available.
Module 4
- 1. 5.1 Module-4 Analog Transmission Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 2. 5.2 5-1 DIGITAL-TO-ANALOG CONVERSION5-1 DIGITAL-TO-ANALOG CONVERSION Digital-to-analogDigital-to-analog conversion is the process ofconversion is the process of changing one of the characteristics of an analogchanging one of the characteristics of an analog signal based on the information in digital data.signal based on the information in digital data. Amplitude Shift Keying Frequency Shift Keying Phase Shift Keying Quadrature Amplitude Modulation Topics discussed in this section:Topics discussed in this section:
- 3. 5.3 Figure 5.1 Digital-to-analog conversion
- 4. 5.4 Figure 5.2 Types of digital-to-analog conversion
- 5. 5.5 Bit rate is the number of bits per second. Note
- 6. 5.6 Figure 5.3 Binary amplitude shift keying
- 7. 5.7 Figure 5.4 Implementation of binary ASK
- 8. 5.8 Figure 5.6 Binary frequency shift keying
- 9. 5.9 Figure 5.7 Bandwidth of MFSK used in Example 5.6
- 10. 5.10 Figure 5.9 Binary phase shift keying
- 11. 5.11 Figure 5.13 Three constellation diagrams
- 12. 5.12 Quadrature amplitude modulation is a combination of ASK and PSK. Note
- 13. 5.13 Figure 5.14 Constellation diagrams for some QAMs
- 14. 5.14 5-2 ANALOG AND DIGITAL5-2 ANALOG AND DIGITAL Analog-to-analog conversion is the representation ofAnalog-to-analog conversion is the representation of analog information by an analog signal. One may askanalog information by an analog signal. One may ask why we need to modulate an analog signal; it iswhy we need to modulate an analog signal; it is already analog. Modulation is needed if the medium isalready analog. Modulation is needed if the medium is bandpass in nature or if only a bandpass channel isbandpass in nature or if only a bandpass channel is available to us.available to us. Amplitude Modulation Frequency Modulation Phase Modulation Topics discussed in this section:Topics discussed in this section:
- 15. 5.15 Figure 5.15 Types of analog-to-analog modulation
- 16. 5.16 Figure 5.16 Amplitude modulation
- 17. 5.17 The total bandwidth required for AM can be determined from the bandwidth of the audio signal: BAM = 2B. Note
- 18. 5.18 The total bandwidth required for FM can be determined from the bandwidth of the audio signal: BFM = 2(1 + β)B. Note
- 19. 5.19 Figure 5.18 Frequency modulation