Introduction 4-9
The Nyquist Limit and Aliasing 4-9
The A/D Conversion Process 4-10
Successive Approximation 4-13
Parallel/Flash 4-13
The D/A Conversion Process 4-15
Practical Implementation 4-16
Converter Performance Criteria 4-16
References 4-18
Chapter 4.2: Digital Filters 4-19
Introduction 4-19
FIR Filters 4-19
Design Techniques 4-22
Applications 4-22
Finite Wordlength Effects 4-23
Infinite Impulse Response Filters 4-24
Reference 4-26
Chapter 4.3: Digital Modulation 4-27
Introduction 4-27
Digital Modulaton Techniques 4-27
QPSK 4-28
Signal Analysis 4-29
Digital Coding 4-30
Source Coding 4-30
Channel Coding 4-31
Error-Correction Coding 4-31
Reference 4-32
Chapter 4.4: Digital Video Sampling 4-33
Introduction 4-33
Sampling Techniques 4-34
Digital Coding and Signal Processing
Color Space Issues in Digital Video 4-36
Video as Data 4-36
Gamut and Color Space 4-37
References 4-39
Chapter 5.5: DSP Devices and Systems 4-41
Introduction 4-41
Fundamentals of Digital Signal Processing 4-41
Discrete Systems 4-42
Impulse Response and Convolution 4-42
Complex Numbers 4-46
Mathematical Transforms 4-47
Unit Circle and Region of Convergence 4-51
Poles and Zeros 4-51
DSP Elements 4-53
Sources of Errors 4-54
DSP Integrated Circuits 4-55
DSP Applications 4-56
Digital Delay 4-56
Example DSP Device 4-58
Functional Overview 4-60
References 4-62
On the CD-ROM
• “Digital Television,” by Ernest J. Tarnai—reprinted from the second edition of this handbook.
This chapter provides valuable background information on filter theory, digital transmission methods, and classic digital video applications.
Reference Documents for this Section
Alkin, Oktay: “Digital Coding Schemes,” The Electronics Handbook, Jerry C. Whitaker (ed.), CRC Press, Boca Raton, Fla., pp. 1252–1258, 1996.
Benson, K. B., and D. G. Fink: “Digital Operations in Video Systems,” HDTV: Advanced Televi- sion for the 1990s, McGraw-Hill, New York, pp. 4.1–4.8, 1990.
Chambers, J. A., S. Tantaratana, and B. W. Bomar: “Digital Filters,” The Electronics Handbook, Jerry C. Whitaker (ed.), CRC Press, Boca Raton, Fla., pp. 749–772, 1996.
DeMarsh, LeRoy E.: “Displays and Colorimetry for Future Television,” SMPTE Journal, SMPTE, White Plains, N.Y., pp. 666–672, October 1994.
Garrod, Susan A. R.: “D/A and A/D Converters,” The Electronics Handbook, Jerry C. Whitaker (ed.), CRC Press, Boca Raton, Fla., pp. 723–730, 1996.
Garrod, Susan, and R. Borns: Digital Logic: Analysis, Application, and Design, Saunders Col- lege Publishing, Philadelphia, 1991.
Hunold, Kenneth: “4:2:2 or 4:1:1—What are the Differences?,” Broadcast Engineering, Intertec Publishing, Overland Park, Kan., pp. 62–74, October 1997.
4-4 Section Four
Lee, E. A., and D. G. Messerschmitt: Digital Communications, 2nd ed., Kluwer, Norell, Mass., 1994.
Mazur, Jeff: “Video Special Effects Systems,” NAB Engineering Handbook, 9th ed., Jerry C.
Whitaker (ed.), National Association of Broadcasters, Washington, D.C., 1998.
Nyquist, H.: “Certain Factors Affecting Telegraph Speed,” Bell System Tech. J., vol. 3, pp. 324–
346, March 1924.
Parks, T. W., and J. H. McClellan: “A Program for the Design of Linear Phase Infinite Impulse Response Filters,” IEEE Trans. Audio Electroacoustics, AU-20(3), pp. 195–199, 1972.
Peterson, R., R. Ziemer, and D. Borth: Introduction to Spread Spectrum Communications, Pren- tice-Hall, Englewood Cliffs, N. J., 1995.
Pohlmann, Ken: Principles of Digital Audio, McGraw-Hill, New York, N.Y., 2000.
Sklar, B.: Digital Communications: Fundamentals and Applications, Prentice-Hall, Englewood Cliffs, N. J., 1988.
TMS320C55x DSP Functional Overview, Texas Instruments, Dallas, TX, literature No.
SRPU312, June 2000.
“SMPTE C Color Monitor Colorimetry,” SMPTE Recommended Practice RP 145-1994, SMPTE, White Plains, N.Y., June 1, 1994.
Ungerboeck, G.: “Trellis-Coded Modulation with Redundant Signal Sets,” parts I and II, IEEE Comm. Mag., vol. 25 (Feb.), pp. 5-11 and 12-21, 1987.
Ziemer, R., and W. Tranter: Principles of Communications: Systems, Modulation, and Noise, 4th ed., Wiley, New York, 1995.
Ziemer, Rodger E.: “Digital Modulation,” The Electronics Handbook, Jerry C. Whitaker (ed.), CRC Press, Boca Raton, Fla., pp. 1213–1236, 1996.
Figures and Tables in this Section
Figure 4.1.1 Basic elements of an analog-to-digital converter. 4-10 Figure 4.1.2 Video waveform quantized into 8-bit words. 4-12
Figure 4.1.3 Relationship between sampling rate and bandwidth: (a) a sampling rate too low for the input spectrum, (b) the theoretical minimum sampling rate (Fs), which requires a theo- retically perfect filter, (c) a practical sampling rate using a practical input filter. 4-12 Figure 4.1.4 Successive approximation A/D converter block diagram. 4-14
Figure 4.1.5 Block diagram of a flash A/D converter. 4-14 Figure 4.1.6 Digital-to-analog converter block diagram. 4-15
Figure 4.1.7 Output filter response requirements for a common D/A converter. 4-15 Figure 4.1.8 The filtering benefits of oversampling. 4-16
Figure 4.2.1 The magnitude and phase response of the simple moving average filter with M = 7.
4-21
Digital Coding and Signal Processing
Figure 4.2.2 The impulse and magnitude response of an optimal 40th-order half-band FIR filter.
4-23
Figure 4.2.3 Direct form realizations of IIR filters: (a) direct form I, (b) direct form II, (c) trans- posed direct form I, (d) transposed direct form II. 4-25
Figure 4.3.1 Receiver systems for noncoherent detection of binary signals: (a) ASK, (b) FSK. 4- 28
Figure 4.3.2 The Huffman coding algorithm. 4-31
Figure 4.4.1 Rectangular sampling patterns: (a) rectangular field-aligned; (b) rectangular field- offset; (c) checkerboard; (d) field-aligned, double checkerboard. 4-34
Figure 4.4.2 Comparison of the Y,Cb,Cr and R,G,B color spaces. Note that about one-half of theY,Cb,Cr values are outside of the R,G,B gamut. 4-37
Figure 4.4.3 Color gamut for SMPTE 240M. 4-38
Figure 4.5.1 Two properties of linear-time-invariant discrete (LTD) systems: (a) LDT systems produce an output signal based on the input, (b) an LTD system can be characterized by its impulse response. 4-43
Figure 4.5.2 A graphical representation of convolution: (a) the samples comprising a discrete signal may be considered singly, (b) when applied to a discrete processing system such as a digital filter, each sample produces an output response, (c) the overall response is the sum- mation of the individual responses. 4-44
Figure 4.5.3 Transforms are used to mathematically convert a signal from one domain to another:
(a) analog signals can be expressed in the time, frequency, and s-plane domains, (b) dis- crete signals can be expressed in the sampled-time, frequency, and z-plane domains. 4-47 Figure 4.5.4 Given an input signal x(n) and impulse response h(n) the output signal y(n) can be
calculated through: (a) direct convolution, or (b) Fourier transformation, multiplication, and inverse Fourier transformation. In practice, the latter method is often an easier calcula- tion. 4-48
Figure 4.5.5 Examples of a periodic signal applied to an N-point DFT for three different values ofN. Greater resolution is obtained as N is increased. When N is not equal to an integral number of waveform periods, spectral leakage occurs. 4-50
Figure 4.5.6 The frequency response of a filter can be obtained by dividing the magnitude of the zero vector by that of the pole vector: (a) an example of a z-plane plot of a lowpass filter showing the pole and zero locations, (b) examination of the plot reveals the filter frequency response. 4-52
Figure 4.5.7 The three basic elements in any DSP system: delay, multiplication, and summation.
4-53
Figure 4.5.8 LTD systems can be characterized by their impulse responses: (a) simple nonrecur- sive system and its impulse response, (b) simple recursive system and its impulse response.
4-54
Figure 4.5.9 A delay block can be used to create an echo circuit: (a) the circuit contains an mT delay and gain stage, (b) with shorter delay times, a comb filter response will result. 4-57
4-6 Section Four
Figure 4.5.10 A recursive comb filter creates a delay with feedback, yielding a toothed frequency response. 4-57
Figure 4.5.11 Functional Block Diagram of the TMS320C55x DSP series. 4-61 Figure 4.5.12 Block diagram of EMIF for the TMS320C55x DSP. 4-62 Table 4.1.1 Binary Values of Amplitude Levels for 8-Bit Words. 4-11 Table 4.1.2 Representative Sampling of Converter Operating Parameters. 4-17 Table 4.3.1 Example of the Differential Encoding Process. 4-29
Table 4.5.1 Characteristics of the TMS320C55x Processors. 4-59 Digital Coding and Signal Processing
Subject Index for this Section A
adder overflow limit cycle 4-24 aliasing 4-9
aliasing effects 4-10 all-pass filter 4-57 all-pass network 4-53 alpha channel 4-35
amplitude-shift keying (ASK) 4-27 analog-to-digital conversion (A/D 4-9 analog-to-digital converter 4-10 arithmetic/logic unit 4-60 B
bandwidth 4-30
bandwidth efficiency 4-29 bit stream 4-11
block coding 4-32 C
channel coding 4-30, 4-31 code rate 4-32
coding gain 4-32 coefficient design 4-22 coefficient errors 4-54
coefficient quantization error 4-23 coherent modulation 4-27 coherent receiver 4-28 color gamut 4-38 color space 4-36
color-difference components 4-35 complex number 4-46
computation error 4-54
constant-amplitude network 4-53
continuous phase modulation (CPM) 4-29 continuous transform 4-47
conversion time 4-17 convolution 4-43, 4-45 convolutional coding 4-32 D
D/A converter 4-16 delta function 4-43 DFT 4-49
differential linearity 4-18
differentially coherent PSK (DPSK) modulation 4-28
digital coding 4-30 digital dithering 4-55 digital filters 4-19 digital headroom 4-36 digital modulation 4-27
digital signal processing (DSP) 4-1, 4-41 direct form filter realization 4-24 discrete Fourier transform 4-49 discrete frequency 4-47 discrete system 4-42 discrete time 4-47 discrete transform 4-47 DSP device 4-58 dynamic range 4-1 E
embedded DSP 4-1 entropy 4-31 error correction 4-31 F
FFT 4-49