Single pole filter, difference equation and documentation

GNU Radio
1

Hi,

I notice from the documentation that all of the different
single_pole_* filters have the same difference equation. Is this
correct?

–
Trond D.

2

On Fri, May 11, 2007 at 01:01:44PM +0200, Trond D. wrote:

Hi,

I notice from the documentation that all of the different
single_pole_* filters have the same difference equation. Is this
correct?

–
Trond D.

I was wondering that myself the other day :wink:

I haven’t had the time to check them out yet.

Eric

3

gr_single_pole_avg filter kernel:

output = d_alpha * input - d_one_minus_alpha * d_prev_input;
d_prev_input = input;

gr_single_zero_avg filter kernel:

output = d_alpha * input + d_one_minus_alpha * d_prev_input;
d_prev_input = input;

gr_single_pole_iir filter kernel:

output = d_alpha * input + d_one_minus_alpha * d_prev_output;
d_prev_output = output;

gr_single_pol_rec filter kernel:

output = d_alpha * input + d_one_minus_alpha * d_prev_output;
d_prev_output = output;

So it looks like the first three blocks compute different things but the
fourth is a duplicate of the third. The difference equation in the
header files is the same for all four, but is only correct for the last
two.

–
Johnathan C.
Corgan Enterprises LLC
http://corganenterprises.com