Designing a lowpass filter with lesser filter coefficients with the required parameters
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Hi,
I am currently using a lowpass fitler as below
d = fdesign.lowpass('Fp,Fst,Ap,Ast',3,8,1,20,500);
Hd1 = design(d);
length=length(Hd1.Numerator);
data1 = filtfilt(Hd1.Numerator,1,data1);
The response of the filter when the input of square pulse is shown below
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/155390/image.jpeg)
But the filter coefficients are of a length of 104 but I want to use lesser filter coefficients(say <20 or some other lesser coefficients) such that the filter perforamnce should be good enough. can someone explain if there is a way of doing it. Thanks.
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AJ von Alt
2014-1-21
编辑:AJ von Alt
2014-1-21
If you do not specify the order of a filter, the design tool will try to minimize the order while satisfying the specified constraints. If you have a specific filter order in mind, I recommend consulting the fdesign.lowpass documentation and selecting a specification that includes N, the filter order.
Here is a simple design adapted from the example article to help you get started.
Fc = 0.4;
N = 20; % FIR filter order
Hf = fdesign.lowpass('N,Fc',N,Fc);
Hd1 = design(Hf,'window','window',@hamming,'SystemObject',true);
hfvt = fvtool(Hd1,'Color','White');
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nam bui
2021-2-12
Hello sir,
I tried to implement the piece of code you provided above but it said I need a DSP system toolbox license but I still have the signal processing toolbox under my matlab license. I'm wondering is there like an alternative way to do it?
Thank you
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