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Buku Dasar yang mengajarkan mengenai teknik elektronika tingkat dasar
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11
Chapter One Prologue
1.0 Scope and Goals
1.1 Signal Processing
1.2 Illustrative Systems
1.3 Modeling
Contents of this Chapter:
Page 2Chapter One Prologue
1.0 Introduction: Scope and Goals• The scope of electronic circuits
Science , Engineering , Medicine , Maintenance ,Espionage
......• The goals of this course
1. Introducing the fundaments of circuit's analysis and sy
nthesis.
2. Introducing the principle of the construction of electro
nic system.
3. Introducing the basic applications of electronic circuits.
Page 3Chapter One Prologue
1.1 SIGNAL PROCESSING
1.1.1 What is a signal? • Information The uncertain quantities for the receivers. For example, news involves some unknown message, so we can say that it has information. If someone told you "news" you had known, the "news" would have not any information
• Signal Some physical variables carried information. Such as sound, images, text, voltage, current, etc. In electronic system, signals are general voltage or current. Signal can be classified two kinds
Page 4Chapter One Prologue
1.1.2 Analog and Digital Signals • Analog Signal The signal (voltage or current) varies continuously with time. For example
• Digital Signal The signal has only two possible values, 0, 1. And the signal can only change its value in discrete time points. For example
Page 5Chapter One Prologue
1.1.3 Signal Processing Systems • The dialog of signal processing system
Page 6Chapter One Prologue
• Input signals 1. Analog input signal, come from analog transducers, such as
thermocouples2. Digital input signal, come from computer or other digital
system.
• Signal processing module 1. Analog sub-system processes the analog signals.2. Digital sub-system processes the digital signals.
• A/D and D/A conversion 1. A/D analog signal To digital signal (Lossless)2. D/A digital signal To analog signal (Lossless)
• Output signal 1. Analog output signal to analog device for displaying,
controlling.2. Digital output signal to computer or digital device for
displaying, controlling, etc.
Page 7Chapter One Prologue1.2 Illustrative Systems • A Communications System
An AM broadcast communication system 调幅广播通信系统
Page 8Chapter One Prologue
Transmitting system is called AM transmitter ( 调幅发射机)Receiving system is called AM receiver ( 调幅接收机)AM —— Amplitude Modulation (调幅), the amplitude of RF sign
al varies according to the magnitude of a lower-frequency signal (a
udio, corresponding to audible frequencies).
FM —— Frequency Modulation ( 调频), the frequency of RF signa
l varies according to the magnitude of a lower-frequency signal (au
dio, corresponding to audible frequencies).
RF —— Radio frequency ( 射频), it can be radiated and inducted b
y an antenna. Each broadcast station is assigned its own radio frequ
ency. In our country the RF of AM broadcast is from 530 kilo Hz t
o 1600 kilo Hz, and the RF of FM broadcast is from 88 million Hz
to 108 million Hz,
Page 9Chapter One Prologue
Transmitter 发射机 Control the amplitude of the RF signal using the input signal;
Drive the output device (the antenna) with RF current to produc
e electromagnetic waves radiating into space.
Receiver 接收机 Amplify the signal obtained from the antenna;
Filter the desired radio frequency signal from the signals of all o
ther broadcast stations;
Recover or select the audio signal from the amplitude variations
of the radio frequency signal;
Drive a loudspeaker with the recovered audio signal.
Page 10Chapter One Prologue• A Measurement System
The purpose of a measurement system is to acquire information f
rom suitable transducers( 传感器 ) about the behavior of some p
hysical system and to display this information to the observer.
Page 11Chapter One Prologue• Transducer—— pair of thermocouple junctions, one attached to th
e object whose temperature is to be measured, the other submerged in an ice bath (to establish a stable reference point 0ºC)
• Input signal—— a voltage generated by the transducer depending on the temperature difference between the object to be measured and the reference point.
• Amplifier—— amplify the input analog voltage signal to a sufficient amplitude.
• Linearizer—— linearize the analog voltage signal so that which is exactly proportional to the temperature.
• A/D Converter—— convert the linearized analog voltage to digital form.
• Digital display register 数字显示寄存器—— register and display the digital signal produced by A/D converter. The digital signal in the register is refreshed periodically.
Page 12Chapter One Prologue
1.3 Modeling
• Why modeling 1. Practical components in real electronic system differ in thousands
of ways.2. The main characteristic of real components can be presented with
some basic functions.3. The basic laws and theories of electrical networks should have
been universal
• How modeling 1. Define some basic ideal components called component model (the
less the better): such as resistor, capacitor, and inductor.2. According to the main characteristic of real device, present the real
device by a combination of component models.