Parameters of analog and digital signal
Analog and digital signals
pp 8-16
At the end of this chapter, the student must:
• Learn what it does and what the Electronic applications are
• Avalyei similarities and differences between analog and digital signals and circuits.
• Avtilamvavetai their use in everyday life.
1.1 General principles electronic
In every place that we live and work around our electronic devices. The phone is now online. The TV is composed of electronic circuits. The video, the LDC, the computer is some of the electronic devices we encounter in our everyday lives.
E is called the branch of science and technology that deals with electronic devices and use them.
The E took its name from the electron diffusion is the body's power to these devices. In modern times the technician must necessarily be aware of electronic ¬ u to be able to operate, repair, maintain and configure all these electronic devices.
The electronic devices are divided into household - such as consumer TV, video, amp, cd player, etc. telecommunications such as telephones (wireline, wireless, mobile), fax (LDC), telephones, radios and instrumentation such as voltmeters, ammeters, oscilloscopes, such as biomedical ECG, ultrasound, etc. Figure 1.1.1 seem certain electronic devices.
Schima1.1.1 Electronics
These devices consist of electronic components to consider in subsequent chapters. These electronic components are manufactured either in discrete form or as part of a single circuit with more accessories that are placed in the same shell called a chip (ok)
The fundamentals of Electronics, which is essentially applied physics governing the movement of electrons through the conductors of the semiconductor electronic components.
Electronic governed by certain laws and theorems dealing with the lesson Circuits dc and ac current, and will be analyzed in subsequent chapters.
The electronics is a branch of science which is developing rapidly. Before 30 - 40 years television was a bulky device with a very heavy burden that consumes enough power. Today television has a flat screen, lower weight, lower consumption, higher resolution and additional features such as remote control, teletext etc.
Similarly, the computer was a machine that occupied volume of a room, it was very slow, had no memory and did simple operations. Today, the H / PC can be placed in one corner of the office work is very fast, programmed to perform complex operations, and many other functions are accessible
In a few years the development of e will be so great that it will "wear" a multi-function zone, which is both a computer, mobile phone, printer, radio and television. And all this with the help of the modern MIKROILEKTRONIKIS ELECTRONIC TECHNOLOGY.
1.2 Analog and digital signals
Analog is the signal which is constantly changing with time and is theoretically infinite values.
Analog signals that express natural phenomena is the temperature of a room, the pressure of a container with liquid or gas, the car's speed, the voltage of a voltage source, etc. Called analog because their price is proportional to the natural phenomenon represent.
Figure 1.2.1 Circuit voltage divider
An example is the analog signal voltage of a battery. Suppose we have a nominal battery voltage Vi = 10 Volt. We can take multiple values using a voltage divider connected as in Figure 1.2.1.
When the middle divider is taking over the position (1) then:
V23 = V13 = 10 Volt.
In the down position (3): V 23 = V3 = 0V.
For each intermediate drawing (2) we get: 0 <V23 <10 V.
Natural phenomena are expressed in proportional sizes such as sound, temperature, humidity, air pressure, power and wind speed etc. The human speech, the radio signal, the intensity of electric current corresponding to analog signals. The signals can be
plotted with various shapes such as sine, triangular, the other curves. Figure 1.2.2 (a) depicts the signal sounds a speaker, where each has a different grapheme sound waveform.
Figure 1.2.2 (b) attend a sine wave is a harmonic signal with period T, amplitude A and frequency f = 1 / T.
Essentially, each signal can be represented by many sinusoidal
Figure 1.2.2 Analog signals. (A) Signal speech sounds. (B) sinusoidal signal (c) radio signal amplitude.
signals. Finally in Figure 1.2.2 (c) shows a radio signal
amplitude modulation (AM) is a composite signal.
Digital signal is a signal takes only discrete values,
expressed by certain numbers such as 1, 3, 7,
-5, 8, -4, etc.
A digital signal can be derived from the corresponding analog
when the count at specific times.
In the previous example of the voltage divider (Fig. 1.2.1), if
measure the voltage at various positions of receivers will have a
sequence voltages as 1V, 1,5 V, 2,3 V, 6,5 V, 8,1 V, 9V and 10V. The
These numbers represent digital signals, digital signals can get a wide range of prices.
Figure 1.2.3 appears with a red line of constant change
analog voltage 0 - 10V, while the discrete (digital) values are indicated by green lines.
making tools
Figure 1.2.3 Calibration of voltage changes, voltage divider
We will deal with a particular class of digital signals take only 2 values, the logical value "0" and the logical value "1" called bits (Bits). The digital signals are units that are the zeros are very useful because it can be produced very easily, eg closed switch - lamp on = logical "1" open switch - lamp off = logical "0" circuit current carrying = logical "1" = open circuit logical "0".
The digital signal is also called logical "1" +5 V voltage is called HIGH, while the logical "0" voltage is 0V and called LOW.
The digital signal can come from a battery and a switch as in Figure 1.2.4.
Figure 1.2.4.
Creation of digital signal
1.3 Analog and digital circuits
The instruments which measure the analog or digital equivalent amounts of said analog or digital instruments. The speed of a vehicle
measured by the tachometer, pressure gauge, etc. with The electrical quantities that interest us the relief, the voltage with the voltmeter, the intensity of the ammeter and wattmeter with power. The analog multimeter, as shown in Figure 1.3.1, consists of a sliding scale trends and the indication is determined by the position of the needle on the scale.
Called VOM.
In the digital voltmeter, as shown in Figure 1.3.2, a screen shows the value of the measured data in the form of numerical digits.
Circuit is a device in which electrical components are connected in a closed loop.
Closed switch
V "p = 5 V (logic" 1 ")
Open switch
V "p = 0 V (logical" 0 ").
The digital signals of the two situations are called binary (binary) and the signals of computers (H / H).
Figure 1.2.5 illustrates a terminal and a central unit and / or PCs connected by binary digital numbers 0 and 1.
Figure 1.2.5
Computer
Figure 1.3.1
Analog Multimeter
Figure 1.3.2
Digital Multimeter
The larger the circuit antiotaoi RK, tooo smaller the current I.
Unlike a digital circuit, as the vehicle 1.3.4, if you created an analogue oima converted atthe meoo a digital
analog / digital converter (A / D) and then transmitted
for processing in a digital electronic ypologioti (H / H).
Today there is the R taoi, where conditions are right, paradooiaka devices were analog converted to digital. Characteristics of instance is the pick up (analog ouokefi), replaced by the compact disk player (digital ouokefi). Achieving this
Figure 1.3.3
the otochou became possible after ochediaoti-
Analogko circuit even specific circuits analogue-conversion
A simple electrical circuit, as the vehicle 1.3.3, may consist of an electrical source (V |), an electric antiotaoi (R) and one light (L).
In the circuit flows electric current which is expressed by the variable I whose value depends on the circuit ounoliki antiotaoi RK and taoi source of V |, as given by ocheoi (Law of Ohm) (1.3.1):
RK
where RK = R + R § 1.3.1
Analog A / D Digital H / Y
Signal Signal
Figure 1.3.4 Digital circuit
gikou signal to digital and vice versa, because as mentioned natural phenomena expressed by analog signals. Some of the reasons why this happens is the following: a planned easily.
b using digital integrated circuits that are very cheap.
c Digital circuits can store information and processed quickly and reliably. D. There is greater accuracy than analog circuits. e can be programmed for any function. F. Interference and noise affects less digital circuits.
SUMMARY 1
• E is the science that deals with the design, construction and maintenance of electronic devices.
• Analogue signal is a signal that varies continuously with time and takes too many values
• Digital signal is a discrete time and the binary digital signal has only 2 values.
• Analog and digital circuits are those corresponding process analog and digital signals.
QUESTIONS - Exercises
1. From these signals which are analog and digital which:
(A) A Width
(B) Width
(C) a width
2. A sinusoidal signal has a frequency f = 1MHz (106 Hz). To obtain the magazine.
3. Why use more digital signals?
4. What are analog circuits?
5. Making the right match the following elements:
Analog circuit with LED Digital Electronic oima
Digital circuitry Bit Computer
Analog circuit Sine Pulse
History
O 20th century is characterized as the century of ELECTRONIC. The discovery of thermionic diode by A. Fleming in 1901 was the beginning of the electronic revolution. The discovery was made for the purpose of transmitting wireless message from England to America to confirm the discovery of another G. Marconi.
Then we studied the thermionic emission from the Richardson and the next step was the invention of Triode tube in 1906 by Lee De Forest. H triode thermionic valve used to strengthen weak currents. This was followed by Arnold in 1913 which improved the electronic light by observing that the coating of oxide fibers by giving more aid from the metallic threads.
In the coming decades has improved the electronic tube, and added more screens and creating tetrodo pentodo and was almost the exclusive electronic component to aid the discovery of transistors in 1940 by Russell Ohl, then the transistors (Transistor) in 1948. The second transistor has done a revolution in electronic systems giving better yields, lower weight and volume and lower power consumption.
Finally around 1960 discovered that the chip consists of many transistors in an area of just 1 square mm (chip), which is the heart of all current electronic devices such as computer, electronics tv, electronic Mr. PBXs LP
