Define Sampling at a Very High Frequency?

By sampling at a very high frequency compared with the signal frequency, we can ensure that we do not miss important information. Another advantage of sampling at a high frequency is that from the samples, we can rebuild the signal almost as well as the original. As displayed on the diagram above, if we plot the inferred signal from the samples, we will obtain a waveform very similar to the original. When an analog signal is sampled, several images of the spectrum occur in the frequency domain.

These images are centred around the base band (original signal) and multiples of the sampling rate. This is comparable to having multiple analog-mixer circuits.