通信原理课件第03章(对映haykin第四版共10章).pptVIP

Chapter 3Pulse Modulation Figure 3.1The sampling process. (a) Analog signal. (b) Instantaneously sampled version of the analog signal. Figure 3.2(a) Spectrum of a strictly band-limited signal g(t). (b) Spectrum of the sampled version of g(t) for a sampling period Ts = 1/2 W. Figure 3.3(a) Spectrum of a signal. (b) Spectrum of an undersampled version of the signal exhibiting the aliasing phenomenon. Figure 3.4(a) Anti-alias filtered spectrum of an information-bearing signal. (b) Spectrum of instantaneously sampled version of the signal, assuming the use of a sampling rate greater than the Nyquist rate. (c) Magnitude response of reconstruction filter. Figure 3.5Flat-top samples, representing an analog signal. Figure 3.6(a) Rectangular pulse h(t). (b) Spectrum H(f), made up of the magnitude |H(f)|, and phase arg[H(f)]. Figure 3.7System for recovering message signal m(t) from PAM signal s(t). Figure 3.8Illustrating two different forms of pulse-time modulation for the case of a sinusoidal modulating wave. (a) Modulating wave. (b) Pulse carrier. (c) PDM wave. (d) PPM wave. Figure 3.9Description of a memoryless quantizer. Figure 3.10Two types of quantization: (a) midtread and (b) midrise. Figure 3.11Illustration of the quantization process. (Adapted from Bennett, 1948, with permission of ATT.) Figure 3.12Illustrating the partitioning of the dynamic range ?A ? m ? A of a message signal m(t) into a set of L cells. Figure 3.13The basic elements of a PCM system. Figure 3.14Compression laws. (a) m -law. (b) A-law. Figure 3.15Line codes for the electrical representations of binary data. (a) Unipolar NRZ signaling. (b) Polar NRZ signaling. (c) Unipolar RZ signaling. (d) Bipolar RZ signaling. (e) Split-phase or Manchester code. Figure 3.16aPower spectra of line codes: (a) Unipolar NRZ signal. The frequency is normalized with respect to the bit rate 1/Tb, and the average power is normalized to unity. Figure 3.16bPower spectra of line codes: (b) Polar NR