How to deal with this error??

G
Gianna · Jan 27, 2021 · 2.2K views
Question
A model of the surface EMG signal is created by filtering a white gaussian noise, using a shaping filter H(f). this filter has low cut-off freq=60hz and high cut-off freq=120hz. this is my code but i don't know how to deal with Undefined function 'designfilt' for input arguments of type 'char'.   clear all; subplot(322); load nnoise.m; plot(nnoise,'k'); % design shaping filter bpFilt = designfilt('bandpassfir',... 'CutoffFrequency1',60,'CutoffFrequency2',120, ... 'SampleRate',2000); subplot(323); W = filter(bpFilt,nnoise); plot(W,'k');title ('EMG');
Expert Answer
Profile picture of Neeta Dsouza
Neeta Dsouza PhD Expert
Answered Aug 26, 2026
The designfilt function was introduced in the R2014a version of the Signal Processing Toolbox.
 
If you have an earlier version of the Signal Processing Toolbox, this filter will work, since all the functions were introduced prior to R2006a:
 
Fs = 2000;
notch_frq = [50 60 120 130];
mags = [0 1 0];
devs = [0.05  0.01  0.05];
[n,Wn,beta,ftype] = kaiserord(notch_frq,mags,devs,Fs);
n = n + rem(n,2);
hh = fir1(n,Wn,ftype,kaiser(n+1,beta),'scale');

figure(1)
freqz(hh, 1, 2^17, Fs)
Use the filtfilt function to do the actual filtering of your signal.
 
See the documentation on the various functions to understand how to use them.
Have a different question? Ask here

Get a Free Consultation or a Sample Assignment Review!