FIR filter has output of same length as its input?

11 views (last 30 days)
If the input signal has length L samples, impulse repsonse has length M samples, entering these L samples to FIR filter using conv function, will get L+M-1 output samples, while entering these L samples to FIR fitler, the output has L samples only instead of L+M-1 samples . Also, I'd like to know which L samples does FIR filter choose from L+M-1 samples (total samples) to be its output ?.

Accepted Answer

Bruno Luong
Bruno Luong on 27 Dec 2020
Edited: Bruno Luong on 27 Dec 2020
There is the the difference equation in the "Rational Transfer Function" part of the doc. x(i) with i<=0 are supposed to be 0.
and you can figure out easily just by experiment
>> x=rand(1,10)
x =
0.1576 0.9706 0.9572 0.4854 0.8003 0.1419 0.4218 0.9157 0.7922 0.9595
>> b=rand(1,3)
b =
0.9340 0.6787 0.7577
>> conv(x,b) % <= 'full' option
ans =
0.1472 1.0135 1.6722 1.8385 1.8022 1.0435 1.0966 1.2491 1.6810 2.1277 1.2515 0.7270
>> filter(b,1,x)
ans =
0.1472 1.0135 1.6722 1.8385 1.8022 1.0435 1.0966 1.2491 1.6810 2.1277

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!