The most fundamental digital modulation techniques are based on keying: PSK (phase-shift keying): a finite number of phases are used. FSK (frequency-shift keying): a finite number of frequencies are used. ... QAM (quadrature amplitude modulation): a finite number of at least two phases and at least two amplitudes are used.

1. PRESENTATION ON “DIGITAL MODULATION TECHNIQUES”
SAM HIGGINBOTTOM INSTITUTE OF
AGRICULTURE, TECHNOLOGY & SCIENCES
PRESENTED BY:-
PANKAJ SINGH
ID- 13BTECE029
PRESENTED TO:-
Er. MANVENDRA YADAV
Er. PRINU C. PHILIP

2. INTRODUCTION
• In a digital communication system, the source
to be transmitted is discrete both in time and
amplitude
• The source information is normally
represented as a baseband (low-pass) signal
• In digital modulation a high frequency analog
carrier signal is modulated by digital bit
stream

3. What is modulation ?
• Modulation = Adding information to a carrier signal
• The sine wave on which the characteristics of the
information signal are modulated is called a carrier signal

4. Modulations systems

5. Types of digital modulation technique
• Coherent
• Non coherent
Coherent; In coherent modulation technique
process received signal with a local carrier of
same frequency and phase.
Non coherent;In Non coherent digital
modulation technique there is no requirment
of reference wave.

6. Digital modulation technique
• ASK (Amplitude shift keying)
• PSK (Phase shift keying)
• FSK (Frequency shift keying)

7. Amplitude shift keying
In ASK, the amplitude of the signal is changed
in response to information. Bit 1 is transmitted
by a signal of one particular amplitude to
transmit 0, we change the amplitude keeping
the frequency constant.it is shown below

8. Phase shift keying
In PSK,we change the phase of the sinusoidal
carrier to indicate information . To transmit
0,we shift the phase of the sinusoidal by 180
phase shift represents the change in the state
of the information.

9. Frequency shift keying
In FSK,we change the frequency in response
to information one particular frequency for 1
and another frequency for a 0.

10. advantages
• Digital modulation can easily detect and
correct the noise.
• Security is more in digital modulation.
• Digital modulation signal can travels a long
distance.

11. Thank you..