Howtosignalprocessing
- What is the significance of negative frequencies?
- Can sampling rate be negative?
- Why sampling frequency should be twice?
- What happens if sampling is below the Nyquist rate?
What is the significance of negative frequencies?
Negative frequency is an idea associated with complex exponentials. A single sine wave can be broken down into two complex exponentials ('spinning numbers'), one with a positive exponent and one with a negative exponent. That one with the negative exponent is where you get the concept of a negative frequency.
Can sampling rate be negative?
Negative sampling is a technique used to train machine learning models that generally have several order of magnitudes more negative observations compared to positive ones. And in most cases, these negative observations are not given to us explicitly and instead, must be generated somehow.
Why sampling frequency should be twice?
If the signal contains high frequency components, we will need to sample at a higher rate to avoid losing information that is in the signal. In general, to preserve the full information in the signal, it is necessary to sample at twice the maximum frequency of the signal.
What happens if sampling is below the Nyquist rate?
If the Nyquist theorem is not obeyed, higher frequency information is recorded in too low a sample rate, resulting in aliasing artifacts. Several techniques can reduce aliasing in a reproduced signal. Pure sine wave signals do not exist in nature.
