unable to use Low pass filter on experimental data

Hi there

I am trying to filter som data but i get the warning: " Unable to use a value of type 'digitalFilter' as an index."

sfilter = Fx';
noise = 0.5*randn(size(tA));
xfilter = noise + sfilter;

figure()
plot(xfilter) 

dfilter = designfilt('lowpassfir', 'FilterOrder', 5, 'CutoffFrequency', 11, 'SampleRate', fs);

yfilter = filter(dfilter,xfilter);
plot(yfilter)

Where,

sfilter is a 1 x 59992 row vector

Fx' is a 1 x 59992 row vector

noise is a 1 x 59992 row vector

xfilter is a 1 x 59992 row vector

tA is a 1 x 59992 row vector

I hope you can help

Answer 1

[Star Strider]

When I substitute some vectors for the missing data, the posted code runs for me without error.

The filter function should take a digitalFilter object.

Do you have a variable called ‘filter’?

To see if you do, run this:

q = which('filter','-all')

if the first result is:

filter is a variable.  

You have found the problem. (This is called ‘overshadowing’ a MATLAB function.) Ths solution is to rename the variable.

[Ammar Alfaili]

thanx a lot. it's hard to keep track on all the variables when dealing with a long code

Have a nice day :)

[Star Strider]

As always, my pleasure!

You, too!