Analog and Digital Signals
Binary
Code
7th Grade Science
DO NOW MONDAY
• Write down what you think binary code is
or what you think this term means.
Learning Targets
Today’s PLAN
To differentiate
between digitized and
analog signals. .
To explain how binary
code is used to
communicate by
making sound or text
on screens.
Today’s DO
•We will view PowerPoint slides to help us
differentiate between analog and digital signals.
•We will practice decoding binary code messages
and make our own binary code messages.
To differentiate between
digitized and analog
signals. .
To explain how binary code
is used to communicate by
making sound or text on
screens.
Types of Signals
Analog Signals:
• Continuous
• Never-ending range of
values
• More exact, but more
difficult to work with
Digital Signals
• Discrete
• Only 2 values (0 and 1 –
binary code)
• Not as exact, but easier
to work with
Example:
• A digital thermostat in a room displays a temperature of 72. An analog
thermometer measures the room temperature at 72.482.
• The analog value is continuous and more accurate, but the digital value is
more than adequate for the application and significantly easier to process
electronically.
To explain how binary code
is used to communicate by
making sound or text on
screens.
To differentiate between
digitized and analog
signals. .
Examples of Analog Signals:
• Sine waves and square waves are two common
examples of analog signals.
• Digital signals can be square waves too but this
square wave is not digital because it goes into the
negative range (below the x-axis)
0 volts
Sine Wave
Square Wave
(not digital)
Random-Periodic
To differentiate between
digitized and analog
signals. .
To explain how binary code
is used to communicate by
making sound or text on
screens.
Examples of Analog Signals:
• Digital signal are commonly referred to as square
waves or clock signals.
• Their minimum value must be 0 volts (OFF=0),
and their maximum value must be 5 volts (ON=1).
• They can be periodic (repeating) or non-periodic.
5 volts------
0 volts------
Electronics:
How do they work?
ON
OR
OFF
Computer and Circuits
• Are always in one of two states:
– On
– Off
• This is encoded by the Binary System.
• The Binary System tells computers ad
circuits which wires need to be on and
which need to be off.
The Binary System
• Also called the Base-2 System because it
has 2 numbers.
• The number system computers use at the
most basic level.
• Uses only TWO numbers
–0
–1
How does it compare to our
number system?
• Our number system: the decimal system
• Is a Base-10 system because it uses 10
numbers
– 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
• Base-2 System: Binary System
• Uses only 2 numbers
– 0, 1
– O = Off and 1= On
The Binary System
• All circuits are either switched ON (1) of
OFF (0).
• All data is stored as combinations of 0 and
1 (called binary numbers)
– 01
– 101
– 001
– 1001
– 1110
– And so on…..
How does it work?
• Since it is a Base-2 system, all places in
the binary number represent a number
multiplied by 2.
• We will keep it simple and use up to 5 digit
binary numbers.
• This means that we will use binary
numbers that have 5 digits (0’s or 1’s) or
less.
Example
• All blanks will contain either a 0 or 1
(binary number).
• Each blank represents a value. This value
is determined by multiplying the previous
number by 2 (since it is a Base-2 system).
• Always start with a 1, numbering from the
RIGHT SIDE of the blanks
____ _____ _____ _____ _____
16
8
4
2
(8 x 2) (4 x 2) (2 x 2) (1 x 2)
1
Example
• If the blank has a 0 in it, you do not add
the number. (That circuit is off and so is
not counted.)
• If the blank has a 1 in it, then that numebr
is added. (That circuit is on and the is
counted.)
__1_ __0__ __0__ __1__ __1__
16
8
4
2
1
(on) (off)
(off)
(on) (on)
16
+2
+1 = 19
Example
• Then use a chart that tells what number
represents each letter of the alphabet to
determine what letter of the alphabet that
binary number represents.
a
b
c
d
e
f
g
h
i
j
1
2
3
4
5
6
7
8
9
10
k
l
m
n
o
p
q
r
s
t
11
12
13
14
15
16
17
18
19
20
u
v
w
x
y
z
21
22
23
24
25
26
19 = s
So 10011 represents the letter “s” in binary
code
Now Let’s Try Another
• What letter does this binary number
represent?
1
0 1
1
1
16 8 4
2
1
16+
4 +2 +1 = 23 = w
(Remember to add only the numbers that
are ON - have a 1 in the blank)
What letters are represented by the following binary codes?
0
1
1
1
1
1
15
2
21
312
1
0
1
1
0
1
0
1
0
0
Write the following numbers in Binary Code.
15
21
12
Write the following letters in Binary Code.
15J
O
21
12
Y
Are you now able to….
To explain how binary
code is used to
communicate by
making sound or text
on screens.
To differentiate
between digitized
and analogue
signals.
I still feel unsure. I need some more help to understand.
I feel ok. I need to do some more work to check my understanding.
I am happy and feel I understand and can explain the main points.