Upsampling aliasing

1. Does upsampling cause aliasing?
2. What happens in upsampling?
3. Does downsampling cause aliasing?
4. What is the purpose of upsampling?

Does upsampling cause aliasing?

It means creation of frequency components above 1/2 sampling rate of the original signal. Sometimes it is also considered to be a form of aliasing. When you are upsampling by a non-integer ratio (e.g. from 44.1 to 96 kHz), you get both imaging above 1/2 sampling rate of the original signal and aliasing below that rate.

What happens in upsampling?

Upsampling is the process of inserting zero-valued samples between original samples to increase the sampling rate. (This is sometimes called “zero-stuffing”.) This kind of upsampling adds undesired spectral images to the original signal, which are centered on multiples of the original sampling rate.

Does downsampling cause aliasing?

If a discrete-time signal's baseband spectral support is not limited to an interval of width 2 π / M radians, downsampling by M results in aliasing. Aliasing is the distortion that occurs when overlapping copies of the signal's spectrum are added together.

What is the purpose of upsampling?

The purpose of Upsampling is to manipulate a signal in order to artificially increase the sampling rate.