12 init_ soiir2

Purpose

Creates and initializes the variables for the Second Order IIR type-2 adaptive filter. The filter transfer function is given by

$$H(z) = \frac{(1-s)(cos(t) - z^{-1})}{1 - (1+s) cos(t) z^{-1} + s z^{-2}}.$$ (74)

where parameter $s$ controls the filter bandwidth and parameter $t$ controls the filter center frequency.

Syntax

[s,t,u,y,a,b,e]=init_soiir2(s0,t0)
[s,t,u,y,a,b,e]=init_soiir2(s0,t0,u0,y0,a0,b0,e0)

Description

The variables of the SOIIR2 algorithm are summarized below (see Fig. 6.11).

Input arguments [Size]:
  s0  : initial adaptive bandwidth parameter [1x1]
  t0  : initial adaptive center frequency parameter [1x1]
  u0  : last 3 input samples [3x1]
  y0  : last 3 output samples [3x1]
  a0  : last 3 w-gradients [3x1]
  b0  : last 3 s-gradients [3x1]
  e0  : last 3 error samples [3x1]

Output Parameters [default]:
  s   : initialized bandwidth parameter [zero]
  t   : initialized center frequency parameter [zero]
  u   : initialized input buffer [zeros]
  y   : initialized output buffer [zeros]
  a   : initialized w-gradient buffer [zeros]
  b   : initialized s-gradient buffer [zeros]
  e   : initialized error buffer [zeros]

Example

u0 = [.9; .5;.3];
y0 = zeros(3,1);
a0 = [.01;.05;.01];
b0 = zeros(3,1);
% Create and initialize a SOIIR2 filter
[s,t,u,y,a,b,e]=init_soiir2(0.3,0.1,u0,y0,a0,b0);

Remarks

Use input parameters 3 through 7 to initialize the algorithm storage. This is helpful when the adaptation process is required to start from a known operation point calculated off-line or from previous simulations.

See Also

ASPTSOIIR2, ALE_ SOIIR2.