How to filter a signal with a transfer function?
130 views (last 30 days)
Show older comments
Ana Gabriela Guedes
on 26 May 2021
Commented: Star Strider
on 27 May 2021
Hi!
I have a discrete signal (a vector with many values) I want to filter using a low pass filter but I only have the tranfer function in the form. How can I do this since the common filter functions dont use transforms?
0 Comments
Accepted Answer
Star Strider
on 26 May 2021
The easiest approach is to first let the Control System Toolbox solve it, then realise it as a discrete filter using the numerator and denominator vectors —
z = tf('z');
H = (1-z^-6)^2 / (1-z^-1)^2
Num = H.Numerator
Den = H.Denominator
figure
freqz(Num{:}, Den{:}, 2^16)
Use ‘Num{:}’ and ‘Den{:}’ with filtfilt to filter the signal.
Remember that it will be necessary to define a sampling interval, ‘Ts’ where ‘Ts=1/Fs’ where ‘Fs’ is the sampling frequency.
.
2 Comments
Star Strider
on 27 May 2021
No, use the filtfilt function to filter ‘x’.
Assuming that the sampling interval or sampling frequency is defined in the first tf call:
Fs = 1000; % Define Sampling Frequency
Ts = 1/Fs;
z = tf('z',Ts);
H = (1-z^-6)^2 / (1-z^-1)^2
Num = H.Numerator
Den = H.Denominator
figure
freqz(Num{:}, Den{:}, 2^16, Fs)
x = [-233....-667]
x_filtered = filtfilt(Num{:}, Den{:}, x)
and go from there.
.
More Answers (0)
See Also
Categories
Find more on Digital Filtering in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!