Marcin wrote:

> How may I determine cutoff frequency of FIR filter?
> Thanks
> Marcin

Put a sine wave in and measure when the output  goes down 3dB (0.707).

Tom

"Marcin" <faza0123@interia.pl> wrote in message
news:bgoq36$6gh$1@inews.gazeta.pl...
> How may I determine cutoff frequency of FIR filter?
> Thanks
> Marcin
>
>

y=FFT of the array of the FIR coefficients

z=absolute value of y

Examine y.

or, if you want to have a smoother function to look at:

y=FFT of the array of the FIR coefficients with a large number of zeros
first appended to the array of coefficients.

z=absolute value of y

Examine y.

Fred

How may I determine cutoff frequency of FIR filter?
Thanks
Marcin