C64x Real IIR - Filter real input signal using IIR filter

Library

Embedded Coder/ Embedded Targets/ Processors/ Texas Instruments C6000/ Optimization/ C64x DSP Library

Description

The C64x Real IIR block filters a real input signal X using a real autoregressive moving-average (ARMA) IIR Filter. This filter is implemented using a direct form I structure. You must use at least eight input samples.

There must be five AR coefficients and five MA coefficients. The first AR coefficient is always assumed to be one. Inputs, coefficients, and output are Q.15 data types.

The Real IIR block supports discrete sample times and supports little-endian code generation only.

Dialog Box

Coefficient sources

Specify the source of the filter coefficients:

• Specify via dialog — Enter the coefficients in the MA (numerator) coefficients and AR (denominator) coefficients parameters in the dialog box

• Input ports — Accept the coefficients from ports MA and AR

MA (numerator) coefficients

Designate the moving-average coefficients of the filter in vector format. There must be five MA coefficients. This parameter is only visible when Specify via dialog is selected for the Coefficient sources parameter. This parameter is tunable in simulation.

AR (denominator) coefficients

Designate the autoregressive coefficients of the filter in vector format. There must be five AR coefficients, however the first AR coefficient is assumed to be equal to one. This parameter is only visible when Specify via dialog is selected for the Coefficient sources parameter. This parameter is tunable in simulation.

Input state initial conditions

If the input state initial conditions are

• All the same, you need only enter a scalar.

• Different within channels but the same across channels, enter a vector containing the input state initial conditions for one channel. The length of this vector must be four.

• Different across channels, enter a matrix containing all input state initial conditions. This matrix must have four rows.

Output state initial conditions

If the output state initial conditions are

• All the same, you need only enter a scalar.

• Different within channels but the same across channels, enter a vector containing the output state initial conditions for one channel. The length of this vector must be four.

• Different across channels, enter a matrix containing all output state initial conditions. This matrix must have four rows.

Algorithm

In simulation, the Real IIR block is equivalent to the TMS320C64x DSP Library assembly code function DSP_iir. During code generation, this block calls the DSP_iir routine to produce optimized code.

See Also

C64x Real Forward Lattice All-Pole IIR

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