Lowpass filter with L=50?

I'm not sure how to make a lowpass filter with L=50, cutoff frequency 1100Hz with omegac, and a sampling frequency of 8000Hz using the Fourier Series Method.

Answer 1

[Star Strider]

I would use the fir1 function. It seems to do what you want.

Here is my approach:

Fs = 8.0E+3;
Fn = Fs/2;
Fc = 1.1E3;
Fcn = Fc/Fn;
L = 50;

b = fir1(L, Fcn);

figure(1)
freqz(b, 1, 128)

Does it do what you want?

[Dick Rusell]

I forgot to specify that we had the use the Fourier Series Method by finding h.

[Star Strider]

That definitely changes things.

The best resource I can find on that is Low-Pass Filtering by FFT Convolution that also has MATLAB code. All you would need to do is to modify it to your Fs and L. (It’s not an image, so you can copy-paste the code directly from the page.)

I can’t find any MATLAB functions that implement it directly.