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Choosing a Fixed-Point Conversion Strategy

Last Modified: April 26, 2016

When converting the floating-point data types in your design to fixed-point, you choose a conversion strategy that defines how LabVIEW generates initial data type suggestions. LabVIEW uses the conversion strategy you choose to suggest data types for your design that avoid overflow and have sufficient precision to satisfy the strategy requirements.

Before you can choose a fixed-point conversion strategy, you must profile your design. Refer to Profiling Code to Convert to Fixed-Point for help profiling your design.

  1. From the Convert to Fixed-Point tab, choose a conversion strategy for calculating fixed-point data type suggestions.

    The ideal conversion strategy for your design depends on your specific precision and resource requirements:

    Strategy Description
    SNR (dB)

    The Convert to Fixed-Point tool provides initial data type suggestions that the tool predicts will meet the signal-to-noise ratio (SNR) target you specify.

    To use margin of error as the basis of the initial suggestions LabVIEW provides, select SNR (dB) as your strategy. The SNR (dB) strategy provides the most accurate suggestions but does not constrain the number of bits allowed per object.

    Word Length (bits)

    The Convert to Fixed-Point tool provides initial data type suggestions that match the word length (number of bits) you specify.

    If you have strict resource limitations for your design, you may want to use Word Length (bits) to directly control the number of bits for each fixed-point data type.

  2. Specify a target value for calculating fixed-point data type suggestions in the Strategy target value box.

    Depending on the strategy you choose, the target value represents the number of decibels or bits that LabVIEW uses as a goal when calculating data type suggestions.

After you choose a conversion strategy, convert the floating-point data types to fixed-point using suggestions from LabVIEW.

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