MATLAB: Bandpass filter with FDA tool

filterMATLABsignal processing

Hello,

Can I know how to design a bandpass filter with range of 0.5 to 3Hz and needed gain is 80 (if possible 100) which will be used instead of a analog with digital filter.Coming to the sampling freq I have acquired a analog signal(having 1Hz) using a 200Hz sampling rate so I am not sure of what should be perfect sampling frequency is needed. I need the perfect bandpass filter as I will use these filter coefficients generated from fda tool in the microcontroller to design the bandpass with this matlab filter coefficients.

So,for this reason I want to be sure to have a better(perfect) filter implementation so that it won't be problem on the microcontroller filter design. Thanks.

Best Answer

Hi Stefan, yes I'll assume that you downsampled to 50 Hz (using an anti-aliasing filter)

 d = fdesign.bandpass('Fst1,Fp1,Fp2,Fst2,Ast1,Ap,Ast2',0.5,1,3,4,80,0.5,80,50);
 Hd = design(d,'butter');

Or using the butter() function

[z,p,k] = butter(30,[(2*0.5)/50, (2*3)/50],'bandpass');
sos = zp2sos(z,p,k);
fvtool(sos)

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MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

Déjà vu

how to design IIR highpass filter with cutoff frequency of 20Hz and FIR bandpass filter with cutoff frequency of 10Hz and 15Hz?

Make the appropriate changes to get the cascaded filter you want.

MATLAB: Bandpass filter

Hi Magda, We need to know your sampling frequency to give some exact code, but I'll give you a general example and assume a sampling frequency.

I'll assume the data are sampled at 200 Hz. Again you need to use the correct sampling frequency. I'll simply choose to use 40 dB of attenuation in the stopband.

d = fdesign.bandpass('Fst1,Fp1,Fp2,Fst2,Ast1,Ap,Ast2',1,2,11,12,40,0.5,40,200);
Hd = design(d);
fvtool(Hd); % view the filter magnitude response
% filter data with filter()
output = filter(Hd,input);

Note that

    Hd = design(d,'butter');

gives a less expensive (computationally) IIR design. Depending on your sampling frequency and how much attenuation you need, your design can be very expensive.

Best Answer

Related Solutions

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

MATLAB: Bandpass filter

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