ENGG1100|Term2|201415 题香港中文大學 The Chinese University of Hong Kong Analog and digital signals Analog signals: the signal can be any values within the valid range Voltage Example: Range =0>10 Volts 10M E.g. The signal can be 1 356 Volts or2.432∨o|ts Analog value Digital signals: It can only be HGH( or called‘1’) or loW(or called 0). Examples In TTL Transistor-transistor -logic OV standard High=1≈5vots,LoW=0≈0vot Time(ms Usually several bits(more than one Voltage digital bit)are used to represent a One digital Bit number corresponding to an 5V analog value E.g. 8-bit to represent a value from 0 to 28-1=255, or 32-bit to OV represent a value from o to 23-1 Time(ms V15.02.09 Introduction
ENGG1100 | Term 2 | 2014-15 Analog and digital signals • Analog signals: the signal can be any values within the valid range – Example: Range =0 → 10 Volts – E.g. The signal can be 1.356 Volts or 2.432 Volts • Digital signals: It can only be HIGH (or called ‘1’ )or LOW (or called ‘0’). Examples: – In TTL Transistor-transistor-logic standard: • High=‘1’ 5 volts, Low=‘0’ 0 Volt • Usually several bits (more than one digital bit) are used to represent a number corresponding to an analog value • E.g. 8-bit to represent a value from 0 to 28 -1 =255, or 32-bit to represent a value from 0 to 2 32 -1 V15.02.09 Introduction 6 Voltage Time (ms) Voltage Time (ms) 5 V 0 V 10 V 0 V 1 1 Analog value One Digital Bit
ENGG1100|Term2|201415 题香港中文大學 The Chinese University of Hong Kong What is the meaning of digital logic? a signal is represented by 1 or 0 Advantages Easy to be implemented in a circuit Less likely to be interfered by noise temperature and radiation Application, digital music Digital data saved in CDs Analog to Digital conversion( adC) 具 Digital to Analog conversion(DAC) V15.02.09 Introduction
ENGG1100 | Term 2 | 2014-15 What is the meaning of digital logic? • A signal is represented by ‘1’ or ‘0’ – Advantages: • Easy to be implemented in a circuit. • Less likely to be interfered by noise, temperature and radiation. • Application, digital music V15.02.09 Introduction 7 Analog to Digital conversion (ADC) Digital data saved in CDs Digital to Analog conversion (DAC)
1.2 Digital Operations AND, OR NOT V15.02.09 Introduction 8
1.2 Digital Operations AND, OR, NOT V15.02.09 Introduction 8
ENGG1100|Term2|201415 题香港中文大學 The Chinese University of Hong Kong Digital Operations Study how to combine inputs to generate outputs In arithmetic operations: 2 Add 3=5, result is 5 In digital operations: We need a truth table to see the result 3 popular digital operations you will learn here -AND OR Digita NOT(Negation) Input1 Digit Digital operation Digital Output Input2 V15.02.09 Introduction
ENGG1100 | Term 2 | 2014-15 Digital Operations • Study how to combine inputs to generate outputs – In arithmetic operations: 2 Add 3= 5, result is 5 – In digital operations: we need a truth table to see the result • 3 popular digital operations you will learn here – AND – OR – NOT (Negation) V15.02.09 Introduction 9 Digital operation Digital Input1 Digital Input2 Digital Output
ENGG1100|Term2|201415 题香港中文大學 The Chinese University of Hong Kong Exercises Multiple choice questions 1 Are these values digital or analog? emperature: Ans: Humidity: Ans 2) Are you a Chinese Univ. student, the answer is: ans ? ls the above answer analog or digital?: Ans 3)Do you have a mobile phone in your pocket, he answer is: ans Is the above answer analog or digital? Ans 4)What is the temperature in this room the e answer is ans Is the above answer analog or digital? Ans ? Answers 1)Analog, analog 2)Yes, digital 3) Yes, digital 4)20 Degrees, analog V15.02.09 Introduction 10
ENGG1100 | Term 2 | 2014-15 Exercises Multiple choice questions 1) Are these values digital or analog? • Temperature : Ans: _________? • Humidity : Ans: _________? 2) Are you a Chinese Univ. student, • the answer is : Ans_____? • Is the above answer Analog or digital? : Ans:_________? 3) Do you have a mobile phone in your pocket, • the answer is : Ans:______? • Is the above answer Analog or digital? Ans: ________? 4) What is the temperature in this room, • the answer is Ans:___? • Is the above answer Analog or digital? Ans: ________? V15.02.09 Introduction 10 Answers: 1) Analog, analog 2) Yes, digital 3) Yes, digital 4) 20 Degrees, analog