Sampling and Filtering Question

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Jonathan Luong
Jonathan Luong on 10 Sep 2015
Answered: Star Strider on 11 Sep 2015
I have a device that collects data at 50Hz. I use the device to capture a sine wave that has a frequency of 0.16Hz. When I am building a filter for this data using Matlab (butter function) where the cutoff frequency is Wn and is 0 < Wn < 1 where 1 is half of the sample rate, is it referring to the 50Hz of the device or the 0.16Hz of the sine wave I am capturing?

Answers (1)

Star Strider
Star Strider on 11 Sep 2015
It is referring to the 50 Hz of the device.
The normalising frequency that is half the sampling frequency is known as the Nyquist frequency. So you normalise with respect to 25 Hz.

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