I created a filter using filter designer and exported either coefficients, objects, or system objects - how to use filter in Matlab?

It can't be that difficult! The filter is easy to design - it looks perfect. Yet, I have looked and looked at how to implement it in Matlab code - and I can't find out how to do it. Attached is the filter created in the filter designer. I have tried exporting it as a objects, as coefficients, and as system objects. I just want to have it filter it out this little sample check - but nothing works. Why does Matlab have to make it so difficult. Once a filter is made - it should be a simple filter entry to use that filter. But it is not.

Monty

Answer 1

[Garmit Pant]

Hello Monty

I understand that you are trying to design a filter using the MATLAB Filter Designer app and you want to use the filter to filter a signal in your MATLAB code.

You can save and export a filter designed in the Filter Designer app in multiple ways. Two of the ways are listed below:

1. Export as an object to the Workspace:
2. Select File > Export. The Export dialog box appears.
3. Select Workspace from the Export To menu.
4. Select Objects from the Export As menu to save the filter in a filter object.

1. Generating MATLAB Code:
2. Choose File > Generate MATLAB Code > Data Filtering Function

You can refer to the following code snippet to use these created filters in your MATLAB code:

% check filter with add 2 sine signals together 
tcheck=(0:0.0001:0.01); 
ycheck=100*sin(2*pi*500*tcheck)+100*sin(2*pi*1000*tcheck); 
figure (501) 
plot(tcheck,ycheck) 
y500=100*sin(2*pi*500*tcheck); 
figure (502) 
plot (tcheck, y500) 

yfiltercheck = filter(Hd,ycheck); 
%Filter saved in a MATLAB file named 'filterCustom.m' 
hd = filterCustom; 
yfiltercheck2 = filter(hd,ycheck); 

% Plot the filtered data 
figure (601) 
plot (tcheck, yfiltercheck2);title ('Check, Filtered') 
xlabel ('Time (seconds)'); ylabel ('Amplitude'); 
grid on;grid minor 

For further understanding, you can refer to the following MATLAB Documentation:

1. https://www.mathworks.com/help/dsp/ug/using-filter-designer.html - How to use Filter Designer App and export a filter.
2. https://www.mathworks.com/help/signal/ug/filtering-data-with-signal-processing-toolbox.html How to use different filters.

I hope this helps!

Best Regards

Garmit