Question

1. An amplitude modulated system has following parameters: Modulating signal frequency fm = 500 Hz, Carrier frequency fc = 2KHz. Draw a two-sided spectrum with approximately scaled frequencies and amplitude. Consider perfect modulation (mod index = 1).

2. What is the typical range of AM modulation index (depth)? What will happen if it is at the lowest value or highest value in the range? What will happen if it goes beyond the range? too low a level of modulation and the modulation does not utilize the carrier efficiently - too high and the carrier can become over modulated causing sidebands to extend out beyond the allowed bandwidth causing interference to other users.

3. What is the total power of the AM signal? Consider modulation index is m and carrier amplitude is Ac.

4. Modulation efficiency is the percentage of the total power of the modulated signal that conveys information. For modulation index m = 0.8, how much maximum modulation efficiency you get?

5. How much is the bandwidth of the AM signal in terms of carrier and modulating signal frequencies?

Answer 1