In the modern world of electronics, the term Digital is generally associated with a
computer because the term Digital is derived from the way computers perform
operation, by counting digits. For many years, the application of digital electronics was
only in the computer system. But now-a-days, digital electronics is used in many other
applications. Following are some of the examples in which Digital electronics is
heavily used.
Industrial process control
Military system
Television
Communication system
Medical equipment
Radar
Navigation
Signal
Signal can be defined as a physical quantity, which contains some information. It is a
function of one or more than one independent variables. Signals are of two types.
Analog Signal
Digital Signal
Analog Signal
An analog signal is defined as the signal having continuous values. Analog signal can
have infinite number of different values. In real world scenario, most of the things
observed in nature are analog. Examples of the analog signals are following.
Temperature
Pressure
Distance
Sound
Voltage
Current
Power
Graphical representation of Analog Signal (Temperature)
The circuits that process the analog signals are called as analog circuits or system.
Examples of the analog system are following.
Filter
Amplifiers
Television receiver
Motor speed controller
Disadvantage of Analog Systems
Less accuracy
Less versatility
More noise effect
More distortion
More effect of weather
Digital Signal
A digital signal is defined as the signal which has only a finite number of distinct
values. Digital signals are not continuous signals. In the digital electronic calculator, the
input is given with the help of switches. This input is converted into electrical signal
which have two discrete values or levels. One of these may be called low level and
another is called high level. The signal will always be one of the two levels. This type of
signal is called digital signal. Examples of the digital signal are following.
Binary Signal
Octal Signal
Hexadecimal Signal
Graphical representation of the Digital Signal (Binary)
The circuits that process the digital signals are
called digital systems or digital circuits. Examples of the digital systems are following.
Registers
Flip-flop
Counters
Microprocessors
Advantage of Digital Systems
More accuracy
More versatility
Less distortion
Easy communicate
Possible storage of information
Comparison of Analog and Digital Signal
S.N. Analog Signal Digital Signal
1 Analog signal has infinite values. Digital signal has a finite number of
values.
2 Analog signal has a continuous nature. Digital signal has a discrete nature.
3 Analog signal is generated by transducers and Digital signal is generated by A to D
signal generators. converter.
4 Example of analog signal − sine wave, triangular Example of digital signal − binary
waves. signal.
A digital system can understand positional number system only where there are a few
symbols called digits and these symbols represent different values depending on the
position they occupy in the number.
When we type some letters or words, the computer translates them in numbers as
computers can understand only numbers. A computer can understand the positional
number system where there are only a few symbols called digits and these symbols
represent different values depending on the position they occupy in the number.
A value of each digit in a number can be determined using
The digit
The position of the digit in the number
The base of the number system (where base is defined as the total number of
digits available in the number system).
Decimal Number System
The number system that we use in our day-to-day life is the decimal number system.
Decimal number system has base 10 as it uses 10 digits from 0 to 9. In decimal number
system, the successive positions to the left of the decimal point represents units, tens,
hundreds, thousands and so on.
Each position represents a specific power of the base (10). For example, the decimal
number 1234 consists of the digit 4 in the units position, 3 in the tens position, 2 in the
hundreds position, and 1 in the thousands position, and its value can be written as
(1×1000) + (2×100) + (3×10) + (4×l)
(1×10 ) + (2×10 ) + (3×10 ) + (4×l0 )
3 2 1 0
1000 + 200 + 30 + 1
