Clear Filters
Clear Filters

Remove noise from time series data

19 views (last 30 days)
Hello Matlab community,
I have a time series data from different levels with 30 min interval. I tried to use the medfilt1 to remove outliers and worked at some level.
Here is the plot of data1:
And here is the plot of data2:
However what I want to remove is the red crossed parts of the each level. I marked the purple data as an example. I do not want to make a perfectly smooth data but only to remove fluctuations exist at some points.
I wanted to apply 3 sigma method as an option and integrated the code of Adam Danz' code as below but I should have done something missing.
m = mean(data2);
sd = std(data2);
outliers = false(size(data2));
outliers(data2 < m-sd*3) = true;
outliers(data2 > m+sd*3) = true;
t = 1:length(data2);
plot(t, data2, 'b.')
hold on
plot(t(outliers), d(outliers), 'ro')
rh = refline(0,m);
set(rh, 'color', 'm')
rh2 = refline(0,m+sd*3);
rh3 = refline(0,m-sd*3);
set([rh2,rh3], 'color', 'm', 'linestyle', '--')
legend('data', 'outliers', 'mean', '3rd sd')
All I want to do is to filter the fluctiations for each level but I really get confused about what I am doing.
I will glad to hear your suggestions.

Accepted Answer

Star Strider
Star Strider on 22 Jun 2022
The sgolayfilt function might be a better option.
Try something like this —
FrameLen = 201;
DataFilt = sgolayfilt(data1, 3, FrameLen);
plot(t, DataFilt)
Experiment with various values of ‘FrameLen’ to get the result you want.
Cakil on 22 Jun 2022
Thank you for your support, it was very helpful.

Sign in to comment.

More Answers (0)




Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!