7 init_ csoiir2

Purpose

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

$$H(z) = \frac{(1-s)(cos(t) - z^{-1})}{1 - (1+s) cos(t) z^{-1} + s z^{-2}}.$$ (63)

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

Syntax

[s,t,u,y,a,b,p]=init_csoiir2(M,s0,t0)
[s,t,u,y,a,b,p]=init_csoiir2(M,s0,t0,u0,y0,a0,b0,p0)

Description

The CSOIIR2 algorithm is used to simultaneously estimate and track any changes in multiple spectral lines (multiple harmonic signals). The variables of the CSOIIR2 algorithm are summarized below (see Fig. 6.1).

Input arguments [Size]:
   M   : number of second order sections
   s0  : initial adaptive bandwidth parameters [1xM]
   t0  : initial adaptive center frequency parameters [1xM]
   u0  : initial last 3 input samples [3xM]
   y0  : initial last 3 output samples [3xM]
   a0  : initial last 3 w-gradients [3xM]
   b0  : initial last 3 s-gradients [3xM]
   p0  : initial input power estimate [1xM]

Output Parameters [default]:
   s   : initialized adaptive bandwidth parameters [zeros]
   t   : initialized adaptive center frequency parameters [zeros]
   u   : initialized input buffer [zeros]
   y   : initialized output buffer [zeros]
   a   : initialized w-gradient buffer [zeros]
   b   : initialized s-gradient buffer [zeros]
   p   : initialized power [zeros]

Example

M     = 2;                % No. of harmonics.
s0    = 0.25*ones(1,M);   % initial s
t0    = 0.1*ones(1,M);    % initial t

% initialize the csoiir2 filter
[s,t,u,y,a,b,p]=init_csoiir2(M,s0,t0);

Remarks

Use input parameters 4 through 8 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

ASPTCSOIIR2, ALE_ CSOIIR2.