Simple Low Pass Filter without Signal Processing Toolbox

Hi all,

I am facing a really stupid issue about filtering noises in a signal. I have to mention that the license bought by my company don't allow access to the signal processing toolbox.

To do so, I simply defined a low pass filter using the "filter" function as follows:

          Heading = AllHeading{1,k}; % the signal to filter
          Time = AllTime{1,k}; % the time vector
          Tnoise = 10; % the cutoff period 
          Te = mean(Time(2:end)-Time(1:end-1)); % the sampling period
          wt = Te/Tnoise; % the normalised cutoff frequency
          Heading_f = filter(1,[1 -wt],Heading); % the filtered signal

I don't know if the transfer function that I defined is wrong or if I am missing some points, but the the signal isn't filtered and is just vertically moved, as if the mean value were increased...

Any help ?

JB

[Hui Puong]

Hello, I wondering how can you apply your code on an excel file data that imported into Matlab with two variables named X and Y?

Thank you in advance

Answer 1

[Image Analyst]

You can use conv() to do linear filtering.

Answer 2

[jb]

Hi, thank you for your answer !

Sorry, I am close to be a "signal processing" dummy, but I thought I can't use the conv function for a IIR filter ?