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C H A P T E R 7 PRINCIPLES OF DIGITAL DATA TRANSMISSION
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.1 Fundamental building blocks of digital communication systems.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.2 Line code examples: (a) on-off (RZ); (b) polar (RZ); (c) bipolar (RZ); (d) on-off (NRZ); (e) polar (NRZ). Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.3 An on-off signal (a) is a sum of a random polar signal (b) and a clock frequency periodic signal (c). Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.4 Random pulse-amplitude-modulated signal and its generation from a PAM impulse.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.5 Derivation of PSD of a random PAM signal with a very narrow pulse of width ε and height hk = ak/ε. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.6 Power spectral density of a polar signal.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7. 7 Split-phase (Manchester or twinned-binary) signal
Figure 7.7 Split-phase (Manchester or twinned-binary) signal. (a) Basic pulse p(t) for Manchester signaling. (b) Transmitted waveform for binary data sequence using Manchester signaling. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.8 Power spectral density (PSD) of an on-off signal.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Half-width rectangular pulses are used.
Figure 7.9 PSD of bipolar, polar, and split-phase signals normalized for equal powers. Half-width rectangular pulses are used. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.10 (a) HDB3 signal and (b) its PSD.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.11 The minimum bandwidth pulse that satisfies Nyquist's first criterion and its spectrum.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.12 Derivation of the zero ISI Nyquist criterion pulse.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.13 Vestigial (raised-cosine) spectrum.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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fx = Rb/4 (r = 0.5); heavy dashed curve, fx = Rb/2 (r = 1).
Figure 7.14 Pulses satisfying Nyquist's first criterion: solid curve, ideal fx = 0 (r = 0); light dashed curve, fx = Rb/4 (r = 0.5); heavy dashed curve, fx = Rb/2 (r = 1). Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.15 Communication using controlled ISI or Nyquist second criterion pulses.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.16 (a) The minimum bandwidth pulse that satisfies
the duobinary pulse criterion and (b) its spectrum. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.17 Equivalent duobinary signaling.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.18 Differential encoded duobinary signaling.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.19 Pulse generation by transversal filter.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.20 (a) Scrambler. (b) Descrambler.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.21 Regenerative repeater.
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Figure 7.22 Zero-forcing equalizer analysis.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.23 Timing extraction.
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Figure 7.24 Error probability in threshold detection.
Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.25 The eye diagram. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.26 Reading an eye diagram.
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Figure 7.27 Eye diagrams of a polar signaling system using a raised cosine pulse with roll-off factor 0.5: (a) over 2 symbol periods 2Tb with a time shift Tb/2; (b) without time shift. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure Ary PAM signaling: (a) four RZ symbols; (b) baseband transmission; (c) the 4-ary RZ eye diagram. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7.29 Eye diagrams of a 4-ary PAM signaling system using a raised-cosine pulse with roll-off factor 0.5: (a) over two symbol periods 2Tb with time offset Tb/2; (b) without time offset. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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Figure 7. 30 (a) The carrier cos ωct. (b) The modulating signal m(t)
Figure 7.30 (a) The carrier cos ωct. (b) The modulating signal m(t). (c) ASK: the modulated signal m(t) cos ωct. Modern Digital and Analog Communication Systems Lathi Copyright © 2009 by Oxford University Press, Inc.
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