Digital Communications Fundamentals and Applications

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					Digital Communications :                                             CHAPTER 4       Digital Communications :                                        CHAPTER 4
                                                          Bandpass Modulation and                                                         Bandpass Modulation and
Fundamentals and Applications                                       Demodulation     Fundamentals and Applications                                  Demodulation




           Figure 4.1     Basic digital communication transformations                               Figure 4.2   Phasor representation of a sinusoid.
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Digital Communications :                                             CHAPTER 4       Digital Communications :                                        CHAPTER 4
                                                          Bandpass Modulation and                                                         Bandpass Modulation and
Fundamentals and Applications                                       Demodulation     Fundamentals and Applications                                  Demodulation




                        Figure 4.3   Amplitude modulation.                                          Figure 4.4   Narrowband frequency modulation.
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Digital Communications :                                             CHAPTER 4       Digital Communications :                                        CHAPTER 4
                                                          Bandpass Modulation and                                                         Bandpass Modulation and
Fundamentals and Applications                                       Demodulation     Fundamentals and Applications                                  Demodulation




                                                                                       Figure 4.6   Two-dimensional signal space, with arbitrary equal-amplitude
   Figure 4.5   Digital modulations. (a) PSK. (b) FSK. (c) ASK. (d) ASK/PSK (APK).                               vectors s1 and s2.
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Digital Communications :                                                   CHAPTER 4             Digital Communications :                                           CHAPTER 4
                                                                Bandpass Modulation and                                                                  Bandpass Modulation and
Fundamentals and Applications                                             Demodulation           Fundamentals and Applications                                     Demodulation




  Figure 4.7   (a) Correlator receiver with reference signals {si(t)}. (b) Correlator receiver    Figure 4.8    Binary correlator receiver. (a) Using a single correlator. (b) Using
                                with reference signals {Ψ(t)}.                                                                     two correlators.
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Digital Communications :                                                   CHAPTER 4             Digital Communications :                                           CHAPTER 4
                                                                Bandpass Modulation and                                                                  Bandpass Modulation and
Fundamentals and Applications                                             Demodulation           Fundamentals and Applications                                     Demodulation




                                                                                                  Figure 4.10   (a) Sampled matched filter. (b) Sampled matched filter detection
       Figure 4.9    Conditional probability density functions; p(z/s1), p(z/s2).                                         example, neglecting noise.
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Digital Communications :                                                   CHAPTER 4             Digital Communications :                                           CHAPTER 4
                                                                Bandpass Modulation and                                                                  Bandpass Modulation and
Fundamentals and Applications                                             Demodulation           Fundamentals and Applications                                     Demodulation




       Figure 4.11     Signal space and decision regions for a QPSK system.                                        Figure 4.12    Demodulator for MPSK signals.
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Digital Communications :                                               CHAPTER 4         Digital Communications :                                            CHAPTER 4
                                                            Bandpass Modulation and                                                               Bandpass Modulation and
Fundamentals and Applications                                         Demodulation       Fundamentals and Applications                                      Demodulation




   Figure 4.13    In-phase and quadrature components of the received signal
                                   vector r.                                                       Figure 4.14   Partitioning the signal space for a 3-ary FSK signal.
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Digital Communications :                                               CHAPTER 4         Digital Communications :                                            CHAPTER 4
                                                            Bandpass Modulation and                                                               Bandpass Modulation and
Fundamentals and Applications                                         Demodulation       Fundamentals and Applications                                      Demodulation




                          Figure 4.15     Mobile radio link.                                                     Figure 4.16    Signal space for DPSK.
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Digital Communications :                                               CHAPTER 4         Digital Communications :                                            CHAPTER 4
                                                            Bandpass Modulation and                                                               Bandpass Modulation and
Fundamentals and Applications                                         Demodulation       Fundamentals and Applications                                      Demodulation




    Figure 4.17 Differential PSK (DPSK). (a) Differential encoding. (b) Differentially
            coherent detection. (c) Optimum differentially coherent detection.                                    Figure 4.18    Quadrature receiver.
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Digital Communications :                                            CHAPTER 4      Digital Communications :                                          CHAPTER 4
                                                         Bandpass Modulation and                                                          Bandpass Modulation and
Fundamentals and Applications                                      Demodulation    Fundamentals and Applications                                    Demodulation




                                                                                     Figure 4.20    Minimum tone spacing for noncoherently detected orthogonal
     Figure 4.19    Noncoherent detection of FSK using envelope detectors.                                        FSK signaling.
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Digital Communications :                                            CHAPTER 4      Digital Communications :                                          CHAPTER 4
                                                         Bandpass Modulation and                                                          Bandpass Modulation and
Fundamentals and Applications                                      Demodulation    Fundamentals and Applications                                    Demodulation




                        Figure 4.21   Quadrature type modulator.                                   Figure 4.22    Lead/Lag relationships of sinusoids.
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Digital Communications :                                            CHAPTER 4      Digital Communications :                                          CHAPTER 4
                                                         Bandpass Modulation and                                                          Bandpass Modulation and
Fundamentals and Applications                                      Demodulation    Fundamentals and Applications                                    Demodulation




          Figure 4.23     Quadrature implementation of a D8PSK modulator.                           Figure 4.24    Modulator/demodulator example.
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Digital Communications :                                            CHAPTER 4      Digital Communications :                                            CHAPTER 4
                                                         Bandpass Modulation and                                                            Bandpass Modulation and
Fundamentals and Applications                                      Demodulation    Fundamentals and Applications                                      Demodulation




                                                                                         Figure 4.26 DPSK detection. (a) four-channel differentially coherent
                                                                                       detection of binary DPSK. (b) Equivalent two-channel detector for binary
      Figure 4.25    Bit error probability for several types of binary systems.                                        DPSK.
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Digital Communications :                                            CHAPTER 4      Digital Communications :                                            CHAPTER 4
                                                         Bandpass Modulation and                                                            Bandpass Modulation and
Fundamentals and Applications                                      Demodulation    Fundamentals and Applications                                      Demodulation




                                                                                      Figure 4.28     Bit error probability for coherently detected M-ary orthogonal
                      Figure 4.27    Ideal PB versus Eb/No curve.                                                          signaling.
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Digital Communications :                                            CHAPTER 4      Digital Communications :                                            CHAPTER 4
                                                         Bandpass Modulation and                                                            Bandpass Modulation and
Fundamentals and Applications                                      Demodulation    Fundamentals and Applications                                      Demodulation




    Figure 4.29     Bit error probability for coherently detected multiple phase
                                       signaling.                                                   Figure 4.30   MPSK signal sets for M = 2, 4, 8, 16.
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Digital Communications :                                         CHAPTER 4        Digital Communications :                                          CHAPTER 4
                                                      Bandpass Modulation and                                                            Bandpass Modulation and
Fundamentals and Applications                                   Demodulation      Fundamentals and Applications                                    Demodulation




 Figure 4.31    In-phase and quadrature BPSK components of QPSK signaling.                            Figure 4.32   MFSK signal sets for M = 2, 3.
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Digital Communications :                                         CHAPTER 4        Digital Communications :                                          CHAPTER 4
                                                      Bandpass Modulation and                                                            Bandpass Modulation and
Fundamentals and Applications                                   Demodulation      Fundamentals and Applications                                    Demodulation




 Figure 4.33    Symbol error probability versus SNR for coherent FSK signaling.      Figure 4.34   Mapping PE versus SNR into PE versus Eb/No for orthogonal
                                                                                                   signaling. (a) Unnormalized. (b) Normalized.
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Digital Communications :                                         CHAPTER 4        Digital Communications :                                          CHAPTER 4
                                                      Bandpass Modulation and                                                            Bandpass Modulation and
Fundamentals and Applications                                   Demodulation      Fundamentals and Applications                                    Demodulation




  Figure 4.35   Symbol error probability for coherently detected multiple phase         Figure 4.36     Symbol error probability for coherently detected M-ary
                                   signaling.                                                                   orthogonal signaling.
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Digital Communications :                                          CHAPTER 4      Digital Communications :                                       CHAPTER 4
                                                       Bandpass Modulation and                                                       Bandpass Modulation and
Fundamentals and Applications                                    Demodulation    Fundamentals and Applications                                 Demodulation




    Figure 4.37     Symbol error probability for noncoherently detected M-ary
                              orthogonal signaling.                                                  Figure 4.38   Example of PB versus PE.
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Digital Communications :                                          CHAPTER 4      Digital Communications :                                       CHAPTER 4
                                                       Bandpass Modulation and                                                       Bandpass Modulation and
Fundamentals and Applications                                    Demodulation    Fundamentals and Applications                                 Demodulation




                                                                                           Figure P4.1




  Figure 4.39     Binary-coded versus Gray-coded decision regions in an MPSK                                                    Figure P4.2
                  signal space. (a) Binary coded. (b) Gray coded.
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