Filter Design Toolbox

Specifying the Quantized Filter Structure

In Filter Design Toolbox, you can create quantized filters with 16 different filter structures:

• Direct form I
• Direct form I transposed
• Direct form II
• Direct form II transposed
• Direct form Finite Impulse Response (FIR)
• Direct form FIR transposed
• Direct form antisymmetric FIR (odd and even orders)
• Direct form symmetric FIR filters (odd and even orders)
• Lattice allpass
• Lattice coupled-allpass filters
• Lattice coupled allpass power-complementary filters
• Lattice Moving Average (MA) minimum phase filters
• Lattice MA maximum phase filters
• Lattice Autoregressive (AR) filters
• Lattice ARMA filters
• Single-input single-output state-space filters

Filter structures are described in detail in the description for the property FilterStructure.

You can create filters with two possible filter topologies:

• A single section
• Cascaded nth-order sections

Topology.   You set the topology when you specify the reference filter coefficients for your quantized filter. See Assigning Reference Filter Coefficients for more information. After you create your quantized filter with the topology you choose, use Filter Design and Analysis Tool (FDATool) in quantization mode to change the filter topology. For more information about FDATool, refer to Chapter 10, Using FDATool with the Filter Design Toolbox.

For example, you can construct a quantized filter with a lattice AR structure by:

1. Specifying a vector of AR reflection coefficients

k = [.66 .7 .44];

2. Constructing a quantized filter with a lattice AR filter structure

Hq = qfilt('latticear',{k});

Notice that:

• You don't have to type the 'FilterStructure' property name at construction
• You specify the reflection reference filter coefficients in a cell array

Basic Filter Properties

Specifying the Data Formats