COMMUNICATION THEORY

1. 20EC403
COMMUNICATION THEORY

2. UNIT I AMPLITUDE MODULATION
Amplitude Modulation- DSBSC, DSBFC, SSB, VSB -
Modulation index, Spectra, Power relations and
Bandwidth – AM Generation – Square law and Switching
modulator, DSBSC Generation – Balanced and Ring
Modulator, SSB Generation – Filter, Phase Shift and
Third Methods, VSB Generation – Filter Method, Hilbert
Transform, Pre-envelope & complex envelope –
comparison of different AM techniques, Superheterodyne
Receiver

3. Introduction
Communication:
Communication is the process of conveying or transferring the
information from one point to another
Examples:
Wireless communication, optical communication, etc…

4. Classification of communication system

5. Modulation

6. Need for Modulation

7. Classification of Modulation

8. Wavelength

9. Radio Frequency Spectrum

10. Classification of Modulation

11. Amplitude Modulation:
Definition:

12. • After modulation, peak amplitude of modulated wave is expressed as

13. AM Envelope (Double Side Band Full Carrier)

14. AM frequency Spectrum & Bandwidth:
Frequency Spectrum:

17. Modulation Index:

18. Modulation Index Calculation:

19. From figure

22. AM VOLTAGE DISTRIBUTION

24. AM POWER DISTRIBUTION

29. Types of AM modulators

30. Low level Modulation

31. High level modulation