Re: [Discuss-gnuradio] Single pole filter, difference equation and documentation.

[Johnathan Corgan]

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 Corgan
Corgan Enterprises LLC
http://corganenterprises.com