11. Introduction (04 hrs)
a) Need for modulation and demodulation in communication systems
b) Basic scheme of a modern communication system.
c) Noise and its different types ( No mathematical derivation)
2. Amplitude modulation (06 hrs)
a) Derivation of expression for an amplitude modulated wave. Carrier and side band
components. Modulation index. Spectrum and BW of AM Wave. Relative power distribution
in carrier and side bands.
b) Elementary idea of DSB-SC, SSB-SC, ISB and VSB modulations, their comparison, and
areas of applications
3. Frequency Modulation (06 hrs)
a) Expression for frequency modulated wave and its frequency spectrum (without Proof and
analysis of Bassel function) Modulation index, maximum frequency deviation and deviation
ratio, BW of signals, Carson’s rule.
b) Comparison of FM and AM in communication systems
c) Narrow band and Wide Band FM.
4. Phase Modulation (06 hrs)
Expression for phase modulated wave, modulation index, comparison with frequency
modulation.
5. Principles of AM Modulators (06 hrs)
Circuit Diagram and working operation of:
a) Collector and Base Modulator
b) Square Law Modulator
- Balanced Modulator
- Ring Modulator
6. Demodulation of AM Waves (02 hrs)
Principles of demodulation of AM wave using diode detector circuit; concept of Clipping and
formula for RC time constant for minimum distortion (no derivation)
7. Principles of FM Modulators (06 hrs)
Circuit Diagram and working of reactance modulator, varactor diode modulator, VCO and
Armstrong phase modulator.
8. Demodulation of FM Waves (04 hrs)
a) Basic principles of FM detection using slope detector
b) Principle of working of the following FM demodulators
- Foster-Seeley discriminator
- Ratio detector
9. Pulse Modulation (08 hrs)
a) Statement of sampling theorem and elementary idea of sampling frequency for pulse
modulation
b) Basic concepts of time division multiplexing (TDM) and frequency division multiplexing
(FDM)
c) Types of pulse modulation-PAM, PPM, PWM (Generation and Detection) and their
comparison