Chapter 2 part C stud_ver

Chapter 2 part C stud_ver - Chapter 2 Part C Data...

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5.1 Chapter 2 Part C Data Communications Fundamentals
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5.2 5-1 DIGITAL-TO-ANALOG CONVERSION 5-1 DIGITAL-TO-ANALOG CONVERSION Digital-to-analog Digital-to-analog conversion is the process of conversion is the process of changing one of the characteristics of an analog changing one of the characteristics of an analog signal based on the information in digital data. signal based on the information in digital data. Aspects of Digital-to-Analog Conversion Amplitude Shift Keying Frequency Shift Keying Phase Shift Keying Quadrature Amplitude Modulation Topics discussed in this section: Topics discussed in this section:
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5.3 Figure 5.1 Digital-to-analog conversion
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5.4 Modulation Schemes Three mechanisms for modulating digital data  into analog i Amplitude Shift Keying (ASK) ii Frequency Shift Keying (FSK) iii Phase Shift Keying (PSK) In addition, there is a better mechanism that  combines changes in both amplitude and phase  – Quadrature Amplitude Modulation (QAM) is  the most efficient in all modern modems
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5.5 Figure 5.2 Types of digital-to-analog conversion
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5.6 Amplitude Shift Keying (ASK) In ASK, the strength of the carrier signal is varied to  represent binary 1 or 0 Both frequency and phase remain constant while the  amplitude changes The peak amplitude of the signal during each bit duration  is constant and its value depends on the bit (0 or 1) ASK is highly susceptible to noise interference Noise usually affects the amplitude, therefore ASK is the  modulating method most affected by noise Popular ASK technique – on-off-keying (OOK) In OOK, one of the bit values is represented by no  voltage. The advantage is a reduction in the amount of  energy required to transmit information
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5.7 Figure 5.3 Binary amplitude shift keying
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5.8 Figure 5.4 Implementation of binary ASK
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5.9 Amplitude Shift Keying (ASK)
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5.10 Frequency Shift Keying (FSK)
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Chapter 2 part C stud_ver - Chapter 2 Part C Data...

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