In general, to reconstruct a signal accurately, the sampling frequency must be at least twice the carrier frequency. While the Nyquist theorem provides this minimum limit, a higher sampling rate is often used to improve signal resolution.
Nyquist Criteria tells us the sampling frequency must be at least twice the highest frequency component present in the signal.
If the baseband message signal is 3 KHz, the sampling frequency must be 6 KHz or above. However, in practical scenarios or simulations, we often keep it ten times more than the message signal for better visualization.
Similarly, for a modulated signal, we should set the sampling frequency at least twice (and ideally ten times) the carrier frequency. Some simulation examples show what happens if the sampling frequency is less than, equal to, or greater than twice the carrier frequency.
1. If the Sampling Frequency is Greater than the Carrier frequency
2. If the Sampling Frequency is Equal to the Carrier frequency
3. If the Sampling Frequency is less than the Carrier frequency
