Principles of Electronic Communication Notes PDF

Principles of Electronic Communication - Important Topics Principles of Electronic Communication - Important Topics 1. Definition and Need of Modulation: - Modulation is the process of varying a carrier signal in accordance with the information signal. - Need: Reduces antenna size, prevents s...

Principles of Electronic Communication - Important Topics Principles of Electronic Communication - Important Topics 1. Definition and Need of Modulation: - Modulation is the process of varying a carrier signal in accordance with the information signal. - Need: Reduces antenna size, prevents signal mixing, extends communication range, enables multiplexing. 2. AM Wave Equation: - s(t) = Ac[1 + m * cos(2 * pi * fm * t)] * cos(2 * pi * fc * t) - Where Ac = carrier amplitude, m = modulation index, fm = message frequency, fc = carrier frequency. 3. Types of Noise in Communication: - Atmospheric: Caused by natural phenomena like lightning. - Thermal: Due to random motion of electrons. - Shot: Caused by discrete electron flow. 4. Signal-to-Noise Ratio (SNR): - SNR = Ps / Pn, where Ps = Signal Power and Pn = Noise Power. 5. Electromagnetic Spectrum: - IR (300 GHz - 430 THz), Visible Light (430 - 790 THz), UV (3 PHz - 30 PHz). 6. Wave Propagation Types:  - Ground Wave: 30 kHz to 3 MHz, AM Broadcasting. - Sky Wave: 3 MHz to 30 MHz, HF Communication. - Space Wave: Line-of-sight, used in FM and TV. 7. Antenna Basics: - Directivity: Concentration of radiated power in a direction. - Yagi-Uda Antenna: Used for VHF/UHF, consists of reflector, driven element, and director. 8. Block Diagram of Superheterodyne Receiver: - Components: RF Amplifier, Mixer, Local Oscillator, IF Amplifier, Detector. 9. Pre-emphasis and De-emphasis: - Pre-emphasis: Boosts high frequencies before transmission. - De-emphasis: Reduces high frequencies after reception. 10. Practice Numerical: - Bandwidth in FM: BW = 2 * (Delta_f + fm). Example: If Delta_f = 75 kHz and fm = 15 kHz, BW = 180 kHz. Practice Questions: 1. Define modulation index for AM and FM. Discuss its importance. 2. Draw and explain the block diagram of a superheterodyne receiver. 3. Compare ground wave and sky wave propagation.