Modulation

Modulation

1. AM power distribution

   • Current calculations

2. Calculation of modulation index

3. Bandwidth / frequency range

   • BW increases with increase in rate of data transmission

4. Types of modulation

   • Analog modulation
   • Digital modulation

5. Modulation by complex signals

6. Mathematical representation

   • Time domain description
   • Frequency domain discription

7. Why modulate

   • Reduces antenna height
     • lamda = speed of light / frequency
       • height of antenna = lamda / 4
   • Avoids mixing of signals
     • Frequency slot allocation
   • Increases range of communication
     • frequency increases / attenuation decreases
   • Improves signal reception quality
     • Signal noise reduces due to modulation techniques

8. AM transmitters

   • Low level
   • High level

9. Disadvantage

   • power inefficient
   • Bandwidth inefficient
   • Prone to noise

10. Modulation index

    • Linear modulation m<=1
    • Over modulation