# Designing a Fixed-Point Filter Part 2: Scaling Filter Coefficients (Digital Filter Design Toolkit)

In Part 1 of this tutorial, you selected a filter structure for the reference floating-point filter. In Part 2 of this tutorial, you scale the coefficients of the filter.

Every filter structure contains accumulators, which might use different data ranges. In this situation, scaling the coefficients of the reference floating-point filter modifies the accumulators to use the same data range and can help you obtain a better filtering result.

Note If you did not complete Part 1 of this tutorial, refer to labview\examples\Digital Filter Design\Getting Started\Tutorials\Designing a Fixed-Point Filter\Designing a Fixed-Point Filter Part 1.vi for a completed version of the digital filter from that part. |

Complete the following steps to scale the coefficients of the reference floating-point filter by using the DFD Scale Filter VI.

- Place the DFD Scale Filter VI on the block diagram.

Place Find

- Wire the
**filter out**and**error out**outputs of the DFD Convert Structure VI to the**filter in**and**error in**inputs of the DFD Scale Filter VI. - Right-click the
**scale type**input of the DFD Scale Filter VI and select**Create»Constant**from the shortcut menu.

A block diagram constant appears above the DFD Scale Filter VI. This constant represents the scale type that this VI uses to scale the filter coefficients. - Click the
**scale type**constant to select the scale type this VI uses to scale the filter coefficients.**Note**This tutorial uses**Time Domain 1-Norm**, the default scale type.

The block diagram now resembles the following figure. - Select
**File»Save**to save the VI.

After you scale the filter coefficients, you can quantize the coefficients of the reference floating-point filter in Part 3 of this tutorial.

Note Refer to labview\examples\Digital Filter Design\Getting Started\Tutorials\Designing a Fixed-Point Filter\Designing a Fixed-Point Filter Part 2.vi for a completed version of the digital filter from this part of the tutorial. |

Previous: Selecting a Filter Structure | Next: Quantizing a Floating-Point Filter |