This PowerPoint presentation discusses amplitude modulation (AM). It defines AM as a process where the amplitude of a carrier signal is altered according to information in a message signal. The presentation shows diagrams of the AM signal components including the carrier signal, modulating signal, and envelope. It also discusses modulation index, bandwidth, power measurements, and applications of AM including broadcasting, CB radio, and aircraft communications.

1. A Power Point Presentation
By
Sagar & Pradeep

2. • Amplitude Modulation is the simplest and earliest
form of transmitters
• AM applications include broadcasting in medium- and
high-frequency applications, CB radio, and aircraft
communications

3.  Amplitude Modulation is a process
where the amplitude of a carrier signal is
altered according to information in a
message signal.
 The frequency of the carrier signal is
usually much greater than the highest
frequency of the input message signal.

4.  The AM signal
 The modulating signal:
 The Carrier Signal:
t
t
m
k
A
t
s c
c cos
1
t
m
t
A
t
c c
c cos
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1
-5
0
5
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1
-1
0
1
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1
-1
0
1

5. The information signal
varies the
instantaneous
amplitude of the
carrier

6. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
-5
-4
-3
-2
-1
0
1
2
3
4
5
t
m
k
A
t
s c 1
 The Envelope:
 The AM Signal
t
t
m
k
A
t
s c
c cos
1

7.  Modulation Index - The ratio
between the amplitudes between
the amplitudes of the modulating
signal and carrier, expressed by the
equation:
c
m
E
E
m =

8. Under modulated (<100%) 100% modulated
Envelope
Detector
Can be used
Envelope Detector
Gives Distorted
signal
Over Modulated
(>100%)

9. To reduce the height of the antenna
To avoid mixing signals
To increase the range of
communication
To improve quality of reception
Lastly to increase over all strength

10.  Signal bandwidth is an important
characteristic of any modulation scheme
 In general, a narrow bandwidth is
desirable
Bandwidth is calculated by:
m
F
B 2

11.  Power in a transmitter is
important, but the most
important power
measurement is that of the
portion that transmits the
information
 AM carriers remain
unchanged with modulation
and therefore are wasteful
 Power in an AM transmitter is
calculated according to the
formula at the right
2
1
2
m
P
P c
t

12. THANK YOU !
TO
ALL