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Topic: how remove unwanted high frequencies in MATLAB?
Replies: 11   Last Post: Apr 23, 2013 3:51 AM

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Derek Goring

Posts: 3,919
Registered: 12/7/04
Re: how remove unwanted high frequencies in MATLAB?
Posted: Apr 22, 2013 9:03 PM
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On Tuesday, April 23, 2013 10:59:08 AM UTC+12, ghasem wrote:
> > Well, when you do the Fourier Series summation, just leave out the components with frequencies greater than f1.
>
> ==========================
>
> exactly,my problem is here.I want to remove frequencies higher than f1,but I don't know how code it in MATLAB?
>
> for example,following code is imperfect.please perfect it.
>
> data1 = rand(1,n) % suppose data1 is my data.
>
> data2 = dct(data) % data2 is discrete cosine transform of data1.
>
>
>
> % now!How draw it's figure in discrete frequency domain and leave out f > f1 ?
>
> ghasem


Interval in frequency is:
df=1/(2*N*dt);
where N is no of data and dt is the interval between data.
f1 corresponds to index no:
indx=round(f1/df);
So, for dct Y:
Y(indx:end)=0;
y=idct(Y);



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