Filtering waveform using matlab

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nlulani

Junior Member level 3 Filtering using matlab

Hi all,
I have a waveform as shown below, I have clearly mentioned in this waveform the imformation which is neccessary for me. Now I want to remove all other noise and wish to see only these sharp pulses without noise.The data is available with me and I want to use matlab for this purpose, I need to know how can do this.

thanks and regards,

echo47 Filtering using matlab

Do you want to change the unwanted points to zero, or do you want to delete the unwanted points so the data set becomes smaller?

I suggest comparing the original data with low-pass filtered data. Wherever the two values are significantly different, those are your important points.

If you provide a link to your data, maybe someone could write you a few lines of MATLAB code.

nlulani

Junior Member level 3 Re: Filtering using matlab

echo47 said:
Do you want to change the unwanted points to zero, .

yes I want to change the unwanted points to zero.
How is that possible i mean actually on time scale (in data points with me) the duration between the two sharp pulses is .5 us. and i dont understand how to identify and draw its FFT so that I can identify the unwanted band and filter it out.

echo47 Filtering using matlab

You don't need an FFT. You can do it visually by choosing a low-pass filter that significantly attenuates the high frequency noise while passing the slower variations.

maui

Member level 3 Re: Filtering using matlab

nlulani

I am no too famiiliar with matlab, but if I were doing that I would create an array the same size, with all values of 0 except for where tha data is valid, then multiply the values in the two arrays.
If you know how many samples you have and where the data is valid creating this second array would be easy. I'm not sure how you would multiply them in matlab (been years since I used it) you might have to make the second array into a vector of opposite orientation then matrix multiply them. not sure.

Maui

Newbie level 6 Re: Filtering using matlab

you can use high pass filter to remove dc and none sharp (no Spike like)
form data by use of this
y=filter(b, a, data)
which b ,a is filter coefficent

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