Howtosignalprocessing
- What is downsample rate?
- How do you downsample data?
- Does downsampling lose information?
- Does downsampling cause aliasing?
What is downsample rate?
Downsampling is the process of reducing the sample rate by an integer factor. A signal can be downsampled by a factor of Q by retaining every Q th sample and discarding the remaining samples. The new slower sample rate is 1/Q of the original faster sample rate.
How do you downsample data?
y = downsample( x , n ) decreases the sample rate of x by keeping the first sample and then every n th sample after the first. If x is a matrix, the function treats each column as a separate sequence. y = downsample( x , n , phase ) specifies the number of samples by which to offset the downsampled sequence.
Does downsampling lose information?
The tail of feature distributions will lose information in downsampling. However, since we typically downsample the majority class, this loss isn't usually a big problem. Filtering PII from your data can remove information in the tail, skewing your distribution.
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.
