Quick review of digital modulation schemes.

1. Digital modulation techniques

2. Modulations 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. Modulation

10. Modulation (1)

11. Digital modulation techniques

12. ASK
• 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

13. FSK (Frequency shift keyring)

14. PSK (Phase shift keyring)