FIR Resampler Filter - 2022.2 English

Library

AI Engine/DSP/Window IO

Description

This block implements the FIR Fractional Asymmetric Interpolation and Decimation filter targeted for AI Engines.

Parameters

Main

Input/Output data type

Describes the type of individual data samples input to and output from the filter function. int16, cint16, int32, cint32, float, cfloat.

Filter coefficients data type

Describes the type of individual coefficients of the filter taps. It should be one of int16, cint16, int32, cint32, float, cfloat and must also satisfy the following rules:

• Complex types are only supported when the Input/Output data type is also complex.
• 32-bit types are only supported when the Input/Output data type is also a 32-bit type.
• Filter coefficients data type must be an integer type if the Input/Output data type is an integer type.
• Filter coefficients data type must be a float type if the Input/Output data type is a float type.

Specify filter coefficients via input port

When this option is enabled, the tool allows you to specify reloadable filter coefficients via input port.

Filter coefficients

This field should be specified with the asymmetric filter coefficients and must be in the range 4 to 240 inclusive.

Interpolation factor

An unsigned integer which describes the Interpolation factor of the filter. It must be in the range 3 to 16.

Decimation factor

An unsigned integer which describes the decimation factor of the filter. It must be in the range 2 to 16. The decimation factor should be less that the interpolation factor and should not be divisible by the interpolation factor.

Input window size (Number of samples)

Describes the number of samples used as an input to the filter function. The number of values in the output window will be the input window size multipled by the Interpolation factor and divided by the decimation factor. In this instance it would result in a fraction number of output samples which would be rounded down.

Scale output down by 2^

Describes the power of 2 shift down applied to the accumulation of FIR terms before output. It must be in the range 0 to 61.

Rounding mode

Describes the selection of rounding to be applied during the shift down stage of processing. The rounding options are as follows:

1. Floor (truncate)
2. Ceiling
3. Round to positive infinity
4. Round to negative infinity
5. Round symmetrical to infinity
6. Round symmetrical to zero
7. Round convergent to even
8. Round convergent to odd

Modes 2 to 7 round to the nearest integer. They differ only in how they round for the value of 0.5.

Advanced

Number of cascade stages

This determines the number of kernels over which the function will be split. A higher number of cascade stages will result in higher throughput at the expense of resources. The value must be in the range 1 to 9.