This document provides an introduction to digital modulation techniques used in communication systems. It discusses the basic block diagram of communication systems, channel capacity, and reasons for choosing encoding techniques. It then defines modulation as adding information to a carrier signal. It describes three main types of digital modulation: ASK which uses two amplitude levels to represent bits, FSK which uses two frequencies, and PSK which uses two phases.

1. B Y
M S . S . Y . S A L U N K H E
Introduction to Digital modulation
techniques

2. Basic block Diagram Communication systems

3. Channel capacity

4. Reasons for choosing encoding techniques

5. 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

6. Analog modulation

7. Digital modulation and demodulation

8. Signal characteristics that can be modified
signal x(t) = A cos(2πft + Φ)
• A – amplitude
• f – frequency
• Φ – phase (initial angle of the sinusoidal function at its
origin

9. ASK(Amplitude shift Keying)
 ASK On-off keying (Amplitude Shift Keying) –
frequency is kept constant, amplitude has 2 levels
(for bit 1 and for bit 0)
The binary sequence 0010110010

10. FSK (Frequency shift keyring)

11. PSK (Phase shift keyring)