Residential Audio & Video Systems Copyright © 2005 Heathkit Company, Inc. All Rights Reserved Presentation 15 – Digital Audio and Video

2 Objectives At the end of this presentation, you will be able to:

3 Explain the difference between analog and digital and give examples of each. Explain the purpose and the basic operation of a digital-to-analog converter (DAC) and an analog-to-digital converter (ADC). Define sampling rate and bit depth and explain how each affects the output of an analog-to- digital or a digital-to-analog conversion. List the most common sampling rates and bit depths used by CDs and DVDs.

4 Electronics Analog Digital

5 Analog Versus Digital

6 Analog Versus Digital

7 Analog Signals 0 Volts +10 Volts -10 Volts

8 Analog Signals 0 Volts

9 Analog Signals 0 Volts

10 Digital Signals 0 Volts + 5 Volts 1 0

11 1 The Digital Signal 0 V +5V 0

12 Analog Examples Broadcast Radio Television Audio

13 Number Systems Decimal – The number system we use in everyday life. Binary – The number system used by most digital circuits.

14 The Decimal Number System Deci means ten. Based on the number ten. Uses ten symbols to represent quantities 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. We represent the quantities zero through nine with a single digit. We represent quantities greater than nine by using combinations of these symbols.

15 The Decimal Number System  To represent the quantity ten requires two digits. To represent the quantity one hundred (which happens to be 10X10) requires three digits. To represent the quantity one thousand (which happens to be 10x10x10) requires four digits.

16 Powers of Ten 10 0 = = = (10  10) = = (10  10  10) = 1, = (10  10  10  10) = 10, = (10  10  10  10  10) = 100, = (10  10  10  10  10  10) = 1,000,000 Exponent

17 The Binary Number System Most common number system used with digital electronics and computers. Based on the number two. Uses only two symbols: 0 and 1. Positional values are determined by powers of two.

18 Distinguishing between Binary and Decimal numbers. Binary numbers will be identified with a subscript 2. For example: Decimal numbers will be identified with a subscript 10. For example: Subscript

19 Binary Symbols and their Values 0 and = = 1 10

20 What do we do when we exhaust the supply of single symbols? When we exhaust single digits, we use two digits. Decimal example: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14… When we exhaust all combinations of two digits, we use three digits. Decimal example: … 98, 99, 100, 101, 102

21 Binary versus Decimal 0 2 = = = = 3 10

22 Binary versus Decimal 0 2 = = = = = = = = 7 10

23 Pronouncing Binary Numbers 10 2 is pronounced one, zero and not ten is pronounced one, one and not eleven is pronounced one, zero, zero and not one hundred.

24 Counting in Binary

25 0, 1, 2, 3 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, … 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, … 998, 999, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007, 1008, 1009, 1010, 1011, 1012, 1013

26 0, 1, 2, 3 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, …. 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, … 998, 999, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007, 1008, 1009, 1010, 1011, 1012, 1013

27 0, 1, 2, 3 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, …. 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, … 998, 999, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007, 1008, 1009, 1010, 1011, 1012, 1013

Decimal Binary Decimal Binary

29 Powers of Two 2 0 = = = = = = = = = = = = 2048 Note: All numbers shown here are decimal.

30 A binary digit is called a bit Least Significant Bit (LSB) Most Significant Bit (MSB)

31 Binary numbers are often given uniform lengths bit8-bit

33 3-bit numbers

34 4-bit numbers

35 Number of Bits Number of States Maximum Number ,53665,535

36 Analog-to-Digital Converter Digital-to-Analog Converter Microphone Audio CD CD Player Speaker

37 Digital-to-Analog Conversion Converts digital data such as binary codes into an equivalent analog voltage or signal. Accomplished by a Digital-to-Analog Converter (DAC). Input is usually a series of parallel binary numbers. Output is usually an analog voltage that is proportional to the binary input.

Input to DAC Output from DAC 3-Bit Digital to Analog Converter (DAC) 0V 7V

39 A 256 Step Saw-tooth Input  Bit Digital to Analog Converter (DAC)

Input to DAC Output from DAC Digital to Analog Converter (DAC)

41 The Basic 8-Bit DAC + - Precision Resistor Network Precision Reference Voltage Electronic Switches Binary Inputs Analog Output Operational Amplifier (Op-amp)

42 Analog-to-Digital Conversion Converts an analog voltage or signal into equivalent digital data such as binary codes. Accomplished by an Analog-to-Digital Converter (ADC). Input is an analog voltage that represents an analog variable such as sound, temperature, pressure, etc. Output is usually a series of parallel binary numbers whose values are proportional to the analog input.

43 Analog to Digital Converter ADC Analog Input Digital Input V 10V

44 The Comparator + - When + input is more positive, output is HIGH. When – input is more positive, output is LOW.

V REF V IN V OUT V REF = +5V V IN Analog Input Comparator Output (V OUT ) +9V -9V 0V +9V -9V Low High T0T0

46 Counter-Ramp ADC 8-bit DAC Binary Counter Output - + Analog Input (V IN ) Clock Reset 1

47 0V 8V bit DAC 8-Bit Counter Output - + Analog Input (V IN ) Clock Reset V IN = +4V

48 Characteristics of DACs and ADCs Sampling Rate Bit Depth

49 0V 3V 1V 2V 6V 4V 5V 7V LSB

50 0V 3V 1V 2V 6V 4V 5V 7V LSB

51 0V 3V 1V 2V 6V 4V 5V 7V

52 16 Samples Of 4-bits each 32 Samples Of 5-bits each Original Sine Wave

53 Audio CD Standard Analog-to-Digital Converter Microphone Audio CD Sampling Rate = 44.1kHz Bit Depth = 16 bits

54 Audio DVD Standard Analog-to-Digital Converter Microphone Audio DVD Sampling Rate = 96 kHz DVD Bit Depth = 16 bits DVD-A Bit Depth = 24 bits

55 Digital Video Analog-to-Digital Converter DVD

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