The document discusses modulation and amplitude modulation. It defines modulation as varying characteristics of a carrier signal in accordance with a modulation wave. Amplitude modulation varies the amplitude of a carrier signal proportionally to the instantaneous value of a modulating signal. The amplitude modulated signal is made up of the carrier signal, modulating signal, and sidebands containing the information. The modulation index indicates the ratio between the modulating signal and carrier amplitudes. Amplitude modulation has applications in broadcasting and communications.

1. MODULATION
BY- SANJAY KUMAR
0900321088
EN-2(A)

2. 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 .

3.  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.

4. 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)

5. fIgUre Types Of ANALOg-
MODULATION

6.  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)

7. 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.

8. fIgUre : AMpLITUDe MODULATION

9. AM – BAsIc DefINITIONs
5
The AM signal:
s ( t ) = Ac [1 + k • m( t ) ] cos ωc t
0
-5
0 0 .0 1 0 .0 2 0 .0 3 0 .0 4 0 .0 5 0 .0 6 0 .0 7 0 .0 8 0 .0 9 0 .1
The modulating signal: 1
m( t ) = Am cos ωct
0
-1
The Carrier Signal: 0 0 .0 1 0 .0 2 0 .0 3 0 .0 4 0 .0 5 0 .0 6 0 .0 7 0 .0 8 0 .0 9 0 .1
1
c( t ) = Ac cos ωc t 0
-1
0 0 .0 1 0 .0 2 0 .0 3 0 .0 4 0 .0 5 0 .0 6 0 .0 7 0 .0 8 0 .0 9 0 .1

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

11. MODULATION INDex
 The ratio between the amplitudes between the
amplitudes of the modulating signal and carrier,
expressed by the equation:
Em
m=
Ec

12. MeAsUreMeNT Of MODULATION
INDex

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

14. MODULATION INDex fOr MULTIpLe
MODULATINg freqUeNcIes
Two or more sine waves of different, uncorrelated
frequencies modulating a single carrier is calculated
by the equation:
2 2
m= + •
m m +•
• 1 2

15. fULL-cArrIer AM: freqUeNcy
DOMAIN
 Time domain information can
be obtained using an
oscilloscope f usb = f c + f m
f lsb = f c − f m
 Frequency domain information
can be calculated using mE c
Fourier methods, but E lsb =E usb =
trigonometric methods are 2
simpler and valid
 Sidebands are calculated
using the formulas at the right

16. BANDwIDTh
• Signal bandwidth is an important characteristic of any
modulation scheme
• In general, a narrow bandwidth is desirable
• Bandwidth is calculated by:
B = 2 Fm
fc-fm fC fc+fm
2fm

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

18. ThANK yOU