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 How to remove noise for signal or curve fit signal
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JannieT

Singapore
7 Posts

Posted - 02/18/2018 :  02:04:32 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Hi,

I have 2 Terahertz Time Domain Signal for fish samples, obtained from Terahertz Reflection Spectroscopy as seen below.







I would like to obtain a graph for the n of complex refractive index of the sample. And this is the original graph I obtained for n.



As the graph for n is very oscillatory and has huge y value range, therefore I thought the problem lies in the reference time domain signal. Therefore, I went to correct time domain signal until as such.




The corresponding change to n is as such. It has small y value variation. However, the number of oscillation increases. Seems like there is a lot of noise. And I performed curve fitting (as shown by the red line), but this does not look right too as n should be greater than 1.




Can I ask how to remove the noise for the signal such that I can perform a better curve fit to my signal?

Any help will be deeply appreciated. Thank you!

arstern

USA
237 Posts

Posted - 02/19/2018 :  12:07:27 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

You may want to try the smoothing feature:
https://www.originlab.com/doc/Tutorials/Smoothing

-Aviel
OriginLab
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JannieT

Singapore
7 Posts

Posted - 02/22/2018 :  6:43:30 PM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
quote:
Originally posted by arstern

Hi,

You may want to try the smoothing feature:
https://www.originlab.com/doc/Tutorials/Smoothing

-Aviel
OriginLab





Hi Aviel,

Thanks for your reply.

Can I ask if there is a way to retain the true edge of the signal and size of the true edge?


As I have applied the methods in the link, they are either too out of shape, or edges may be gone, or may have additional edge coming out.

Below are some of the smoothed signals which are closer to the original signal.


Original Terahertz Time Domain Signal



Wavelet Denoise Signal


Smoothing by wavelet


Savitzky- Golay
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Echo_Chu

China
Posts

Posted - 02/24/2018 :  05:07:17 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Hi,

Would you mind sending us your data so that we can try and discuss with your data?

You could follow the instructions below to send your file.
http://www.originlab.com/index.aspx?go=Support&pid=752

Echo
OriginLab Technical Service

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