# How to make signal smooth using filter?

I have measured the output of a mechanical system and obtained the signal shown at the attached image. I want to make it smoother by removing the chattering (I think it is called chattering). In order to achieve this I used a filter with transfer function:

$$\ T(s) = \frac{30}{s+30}$$

I used this filter to filter the measured data and the result was the the signal at the attached image. I would like to further process the signal to make it as better as possible. Can I achieve what I want by using another type of filter or is there any other process to follow ?

## 1 Answer

From what I can glance :

The chattering seems to be high-frequency compared to your signal of interest, it should not be hard to filter this chattering noise. You simply need to identify the frequency band of your signal and the frequency band of this noise.

Could your perform an FFT to analyze the frequencies of your noise? Then design a filter that will not attenuate your signal of interest while attenuating the noise to an acceptable level.

Is it real-time processing or post-processing?

• If you mean the filter I already applied it was during real time. Now I want to further post-process the one shown at the image. Oct 27 '19 at 1:36
• Could your perform an FFT and analyze what's the spectrum of your signal? You should see low-frequency content and high-frequency content, i.e. the noise.
– Ben
Oct 27 '19 at 1:52
• If you ask me now, no I don’t know how to do it but I would like to learn how to do it. Is there any really good resource from where I could study it ? Oct 27 '19 at 1:54
• Are you using Matlab? Follow this example it should help you mathworks.com/help/matlab/ref/fft.html
– Ben
Oct 27 '19 at 1:57
• Yes, I am using Matlab. Thank you, I will read it, try to implement it and give back some feedback. Oct 27 '19 at 1:59