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McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Analog Transmission

McGraw-Hill©The McGraw-Hill Companies, Inc., Modulation of Digital Data Digital-to-Analog Conversion Amplitude Shift Keying (ASK) Frequency Shift Keying (FSK) Phase Shift Keying (PSK) Quadrature Amplitude Modulation Bit/Baud Comparison

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.1 Digital-to-analog modulation

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.2 Types of digital-to-analog modulation

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Bit rate is the number of bits per second. Baud rate is the number of signal units per second. Baud rate is less than or equal to the bit rate. Note:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Example 1 An analog signal carries 4 bits in each signal unit. If 1000 signal units are sent per second, find the baud rate and the bit rate Solution Baud rate = 1000 bauds per second (baud/s) Bit rate = 1000 x 4 = 4000 bps

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Example 2 The bit rate of a signal is If each signal unit carries 6 bits, what is the baud rate? Solution Baud rate = 3000 / 6 = 500 baud/s

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.3 ASK

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.6 FSK

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.8 PSK

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Quadrature amplitude modulation is a combination of ASK and PSK so that a maximum contrast between each signal unit (bit, dibit, tribit, and so on) is achieved. Note:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.17 Bit and baud

McGraw-Hill©The McGraw-Hill Companies, Inc., Telephone Modems Modem Standards

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 A telephone line has a bandwidth of almost 2400 Hz for data transmission. Note:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.18 Telephone line bandwidth

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Modem stands for modulator/demodulator. Note:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.19 Modulation/demodulation

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.22 Traditional modems

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure K modems

McGraw-Hill©The McGraw-Hill Companies, Inc., Modulation of Analog Signals Amplitude Modulation (AM) Frequency Modulation (FM) Phase Modulation (PM)

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.24 Analog-to-analog modulation

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.25 Types of analog-to-analog modulation

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.26 Amplitude modulation

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 5.29 Frequency modulation