The document discusses amplitude modulation (AM), which is an analog modulation technique. It defines AM as a process that varies the amplitude of a carrier signal in proportion to an information-carrying modulating signal. The carrier signal translates the modulating signal to a higher frequency for transmission. Key aspects of AM include: the AM signal is composed of the carrier signal multiplied by the modulating signal plus the carrier; the modulation index indicates the ratio of modulation amplitude to carrier amplitude; overmodulation occurs when the index is greater than 1; and the signal bandwidth is determined by the modulation frequency and index. Applications of AM include radio broadcasting and aircraft communications.

1. INTrODUcTION
 Modulation is the process by which some
characteristics of a carrier is varied in accordance with a
modulation wave .
Modulation is the process of putting information onto
a high frequency carrier for transmission (frequency
translation).
 such a modification is achieved by mean of a process
called modulation .

2.  In the modulation process, the baseband signle is
called “modulating signal” and anther higher
frequency signal is called as the “carrier”. The carrier
signal will carry the modulating signal to the
destination.

3. DIffereNT Of MODULATION
MeThOD
 Analog modulation - The modulating signal and
carrier both are analogue signal.
TYPES :
Amplitude modulation (AM),
Frequency modulation (FM),
Phase modulation (PM)

4. fIgUre Types Of ANALOg-
MODULATION

5.  Digital modulation - The modulating signal is
a digital signal , but the carrier is an analogue
signal.
TYPES :
Amplitude Shift Keying (ASK),
Frequency Shift keying (FSK),
Phase Shift Keying (PSK)

6. AMpLITUDe MODULATION
Amplitude Modulation is a process of
changing the amplitude of a high
frequency carrier signal in proportion with
the instantaneous value of modulating
signal (information).
 Amplitude Modulation is the simplest and
earliest form of transmitters.

7. fIgUre : AMpLITUDe MODULATION

8. AM – BAsIc DefINITIONs
The AM signal:
The modulating signal:
The Carrier Signal:
( ) t
A
t
c c
c ω
cos
=
( ) ( )
[ ] t
t
m
k
A
t
s c
c ω
cos
•
+
= 1
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
( ) t
A
t
m c
m ω
cos
=

9. AM chArAcTerIsTIcs
 AM is a nonlinear process
 Sum and difference frequencies are created that
carry the information

10. 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 =

11. MeAsUreMeNT Of MODULATION
INDex

12. OverMODULATION
 When the modulation index is greater than 1,
overmodulation is present

13. MODULATION INDex fOr MULTIpLe
MODULATINg freqUeNcIes
Two or more sine waves of different, uncorrelated
frequencies modulating a single carrier is calculated
by the equation:
m =
m1
2
+
m2
2
+
•
•
•

14. fULL-cArrIer AM: freqUeNcy
DOMAIN
 Time domain information can
be obtained using an
oscilloscope
 Frequency domain information
can be calculated using
Fourier methods, but
trigonometric methods are
simpler and valid
 Sidebands are calculated
using the formulas at the right
fusb = fc + fm
flsb =fc −fm
Elsb =Eusb =
mEc
2

15. BANDwIDTh
• 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
=
fC
fc+fm
fc-fm
2fm

16. AppLIcATIONs AMpLITUDe
MODULATION
AM applications include broadcasting in
medium- and high-frequency applications,
 CB radio , and
 aircraft communications

17. ThANK yOU