Chapter 3 Pulse Modulation

Chapter 3 Pulse Modulation
©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Haykin/Communication Systems, 4th Ed
Chapter Outline Sampling: is basic to all forms of pulse modulation. Pulse-amplitude modulation (PAM): is the simplest form of modulation. Quantization: when combined with sampling, permits to digitize analog signals. Pulse-code modulation (PCM): is the standard method used to transmit analog signals by digital means. Time-division multiplexing: provides for the time sharing by a common channel. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Chapter Outline (Continued)
Digital multiplexers: combines many slow bit streams into a single faster stream. Other forms of PCM: delta modulation (DM) and differential PCM (DPCM). Linear prediction: is a basic form of encoding analog message signals at low bit rates as in DPCM. Adaptive forms of DPCM and DM. The MPEG-1/audio coding standard: is a transpa-rent, perceptually loss-less compression system for audio signals. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Sampling Process (Continued)

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. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Signal Reconstruction

Signal Reconstruction (Cont’d)

Figure 3.3 (a) Spectrum of a signal. (b) Spectrum of an undersampled version of the signal exhibiting the aliasing phenomenon. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

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. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Pulse-Amplitude Modulation

Figure 3.5 Flat-top samples, representing an analog signal.

Other Forms of Pulse Modulation

Figure 3.8 Illustrating 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. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Bandwidth-Noise Trade-off

Quantization Process (Cont’d)

Figure 3.9 Description of a memoryless quantizer.

Figure 3.10 Two types of quantization: (a) midtread and (b) midrise.

Pulse-Code Modulation

Pulse-Code Modulation (Cont’d)

Figure 3.13 The basic elements of a PCM system.

Figure 3.14 Compression laws. (a) m -law. (b) A-law.

Figure 3.15 Line 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. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.16a Power 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. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.16b Power spectra of line codes: (b) Polar NRZ signal. The frequency is normalized with respect to the bit rate 1/Tb, and the average power is normalized to unity. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.16c Power spectra of line codes: (c) Unipolar RZ signal. The frequency is normalized with respect to the bit rate 1/Tb, and the average power is normalized to unity. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.16d Power spectra of line codes: (d) Bipolar RZ signal. The frequency is normalized with respect to the bit rate 1/Tb, and the average power is normalized to unity. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.16e Power spectra of line codes: (e) Manchester-encoded signal. The frequency is normalized with respect to the bit rate 1/Tb, and the average power is normalized to unity. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.17 (a) Original binary data. (b) Differentially encoded data, assuming reference bit 1. (c) Waveform of differentially encoded data using unipolar NRZ signaling. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.18 Block diagram of regenerative repeater.

Time-Division Multiplexing

Figure 3.19 Block diagram of TDM system.

Figure 3.20 Conceptual diagram of multiplexing-demultiplexing.

Digital Multiplexers (Continued)

Figure 3.21 Signal format of AT&T M12 multiplexer.

Virtues and Limitations of PCM

Delta Modulation (Cont’d)

Figure 3.22 Illustration of delta modulation.

Figure 3.23 DM system. (a) Transmitter. (b) Receiver.

Delta-Sigma Modulation

Figure 3.25 Two equivalent versions of delta-sigma modulation system.

Linear Prediction (Continued)

Figure 3.26 Block diagram of a linear prediction filter of order p.

Differential PCM (DPCM)

Differential PCM (Continued)

Figure 3.28 DPCM system. (a) Transmitter. (b) Receiver.

Adaptive DPCM (Continued)

Figure 3.29 Adaptive quantization with backward estimation (AQB).

Figure 3.30 Adaptive prediction with backward estimation (APB).

Computer Experiment: Adaptive delta Modulation

Figure 3.32 Waveforms resulting from the computer experiment on delta modulation: (a) Linear delta modulation. (b) Adaptive delta modulation. ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

MPEG/Audio Coding System

MPEG/Audio Coding System (Continued)

Figure 3.33 Illustrating the definitions of masking threshold and related parameters. The high-level signal (masker) lies inside the darker-shaded critical band, hence the masking is more effective in this band than in the neighboring band shown in lighter shading. (Adapted from Noll (1998) with permission of the CRC Press.) ©2000, John Wiley & Sons, Inc. Haykin/Communication Systems, 4th Ed 9/16/2018

Figure 3.34 MPEG/Audio coding system. (a) Transmitter. (b) Receiver.

Chapter 3 Pulse Modulation

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