HELP!!] What is the maximum smapling rate for digitising an audio signal with a max frequency of 20khz?
The “Nyquist limit” determines the minimum sampling rate in order t capture a signal with a particular maximum frequency so that there will be no ambiguity or aliasing when re-creating the signal from the samples. The minimum sampling rate is twice the maximum frequency in the signal. So for a signal with a 20 kHz max frequency, the minimum sampling rate is 40 kHz. In practice, applications like CD audio use a rate of 44.1 kHz to provide a little margin in case there are frequencies higher than 20 kHz, and also because when working with the signal, it must be filtered, and there’s no such thing as a perfect “brick wall” filter right at 20 kHz. If you were to try to filter out everything above 20 kHz by using a 20 kHz filter, you’d actually lose a little bit of the information below 20 kHz as well. So by using a cutoff frequency of 44.1 kHz, this guarantees that even with an imperfect filter, you won’t lose anything below 20 kHz.
