Embedded Target for Texas Instruments C6000 DSPs

Radix-4 Real FIR

Filter a real input signal using a real FIR filter

Library

C62x DSP Library--Filtering

Description

The Radix-4 Real FIR block filters a real input signal X using a real FIR filter. This filter is implemented using a direct form structure.

The number of input samples per channel must be even. The filter coefficients are specified by a real vector, H. The number of filter coefficients must be a multiple of four and must be at least eight. The coefficients must also be in reversed order. All inputs, coefficients, and outputs are Q.15 signals.

The Radix-4 Real FIR block supports discrete sample times and both little-endian and big-endian code generation.

Dialog Box

Coefficient source

Specify the source of the filter coefficients:

• Specify via dialog--Enter the coefficients in the Coefficients parameter in the dialog
• Input port--Accept the coefficients from port H. This port must have the same rate as the input data port X

Coefficients (H)

Designate the filter coefficients in vector format. This parameter is only visible when Specify via dialog is selected for the Coefficient source parameter. This parameter is tunable in simulation.

Initial conditions

If the initial conditions are

• All the same, enter a scalar.
• Different within channels but the same across channels, enter a vector containing the initial conditions for one channel. The length of this vector must be one less than the number of coefficients.
• Different across channels, enter a matrix containing all initial conditions. The number of rows of this matrix must be one less than the number of coefficients, and the number of columns of this matrix must be equal to the number of channels.
  Initial conditions must be real.

Algorithm

In simulation, the Radix-4 Real FIR block is equivalent to the TMS320C62x DSP Library assembly code function DSP_fir_r4. During code generation, this block calls the DSP_fir_r4 routine to produce optimized code.

See Also

Complex FIR, General Real FIR, Radix-8 Real FIR, Symmetric Real FIR

Radix-2 IFFT

Radix-8 Real FIR