FIR Halfband Decimator Stream - 2022.1 English

Library

AI Engine/DSP/Stream IO

Description

This block implements the stream-based FIR Halfband Decimator filter targeted for AI Engines.

Parameters

Main

Input data type/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

Specifies the filter coefficients as a vector of (N+1)/4+1 elements, where 'N' is a positive integer that represents the filter length and must be in the range 4 to 240 inclusive.

Input frame 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 divided by two by virtue of the halfband decimation factor.

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:

• Specifies the number of cascade stages. The tool will guarantee the same.