10 init_ lbpef

Purpose

Creates and initializes the variables required for the Least Mean Squares Lattice Backward Prediction Error Filter.

Syntax

[k,b,P,e,y,x,c]=init_lbpef(L)
[k,b,P,e,y,x,c]=init_lbpef(L,k0,x0,b0,P0)

Description

Figure 5.16: Block diagram of the lattice predictor.

The block diagram of the lattice backward prediction error filter is shown in Fig. 5.2 while the details of the lattice structure showing its internal variables can be seen in Fig. 5.16. A summary of those variables is given below.

Input Parameters [Size]:: 
   L   : number of lattice coefficients
   k0  : initial lattice predictor coefficients [L x 1]
   x0  : initial input delay line [(L+1)x1]
   b0  : initial backward prediction errors [(L+1)x1]
   P0  : initial power of b [(L+1)x1]
Output parameters::
   k   : lattice predictor coefficients [zeros]
   b   : backward prediction errors [random]
   P   : estimated power of b [b .* b]
   e   : forward prediction error [random]
   y   : predictor output [0]
   x   : input delay line [random(L+1,1)]
   c   : equivalent transversal predictor coef.

Example

L  = 5;                 % Number of lattice stages 
k0 = zeros(L,1);        % initial PARCOR coefficients 
b0 = rand(L+1,1);       % initial backward errors
P0 = b0 .* conj(b0);    % initial power of b

% Create and initialize a lattice FPEF
[k,b,P,e,y,x,c]=init_lbpef(L,k0,[],b0,P0);

Remarks

• Supports both real and complex signals and filters.
• Use input parameters 2 through 5 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

ASPTLBPEF, PREDICT_ LBPEF.