Low pass filter using filter coefficient

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Fatema Dalal 2021-2-16

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评论： Fatema Dalal 2021-3-16

Hi,

I want to do low pass filtering of ECG signal. I have filter coefficients and sammpling frequency. With only this much information available is it possible to do low pass filtering?

please help if someone knows!

Thank you in advance.

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Star Strider 2021-2-16

Yes.

Fatema Dalal 2021-2-16

Kindly help me with the steps for the same.

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Star Strider 2021-2-16

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If you have the Signal Processing Toolbox, first check the filter stability and performance with the freqz function.

Then use the filtfilt function to filter the signal.

All the necessary code and other details are explained in the documentation.

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Star Strider 2021-2-16

在 MATLAB Online 中打开

I assume these are FIR filters.

If so, implement them similarly to the way I implemented them in:

Fs = 1000;                                                                  % Use The Correct Sampling Frequency
LPF_b = [ 0.0352   -0.0854   -0.1350    0.4599    0.8069    0.3327];
HPF_b = [-0.3327    0.8069   -0.4599   -0.1350    0.0854    0.0352];
figure
freqz(LPF_b,1, 2^14, Fs)                                                    % Filter Bode Plot
title(subplot(2,1,1), 'Lowpass FIR Filter')
figure
freqz(HPF_b,1, 2^14, Fs)                                                    % Filter Bode Plot
title(subplot(2,1,1), 'Highpass FIR Filter')
EKG_data = rand(1, 1000);

If you want to filter the signal first with the lowpass filter and second with the highpass filter, the filter arguments would be:

LPF_EKG_data = filtfilt(LPF_b,1, EKG_data);                                 % Filter Using Lowpass Filter
HPF_EKG_data = filtfilt(HPF_b,1, LPF_EKG_data);                                 % Filter Using Highpass Filter

With the result of both filters being the output of the highpass filter.

Experiment to get the result you want.

See the documentation for the various funcitons for details on how to use them.

Star Strider 2021-3-16

The easiest way to determine the locations (and amplitudes) of the R-deflections is to use the findpeaks function.

Fatema Dalal 2021-3-16

Yes that is right. But I do not want to use findpeaks function. Instead develop a logic for detecting the R peaks. Hence the need to make R peaks more prominent.

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