1. What is Sample and Hold Scheme.? 2. What is Modulation index and why is it important characteristic of AM.? 3. Why must a product detector be used to recover the message instead of an envelope detector in DSBSC demodulation? 4. Why does frequency of the carrier change? 5. Draw a figure showing two signals are 180 degrees out of phase.? 6. Identify AM signal, Message signal, Upper and Lower envelopes in Figure.? 7. What is the relationship between the message signal's Frequency & Bandwidth. If Fml = 20khz and Fm2 = 30khz, Calculate the Bandwidths respectively.? 8. Mention few methods of demodulating an FM signal.? 9. What is the bandwidth of AM DSB-SC? 10. When the system is said to be a time-invariant system?