LabVIEW Digital Filter Design Toolkit Readme

Version 7.5

February 2005

This file contains information to introduce you to the LabVIEW Digital Filter Design Toolkit 7.5. This file also provides you with help resources you can use while working with the toolkit. The file contains the following information that you need to understand.

Overview

Software Requirements

Installation Instructions

Accessing the Help

Finding Examples

Known Issues

Overview

The Digital Filter Design Toolkit provides a collection of advanced digital filter design tools to supplement the LabVIEW Full Development System. The Digital Filter Design Toolkit helps you design digital filters without requiring you to have advanced knowledge of digital signal processing or digital filtering techniques. With the Digital Filter Design Toolkit, you can design, analyze, and simulate floating-point and fixed-point digital filters.

Without prior knowledge about programming in LabVIEW, you can use the Digital Filter Design Toolkit Express VIs to interact graphically with filter specifications to design appropriate digital filters.

The Digital Filter Design Toolkit provides VIs that you can use to design a digital IIR/FIR filter, analyze the characteristics of the digital filter, change the implementation structure of the digital filter, and process data with the digital filter. Besides the floating-point support, the Digital Filter Design Toolkit provides a set of VIs that you can use to generate a fixed-point digital filter model, analyze the characteristics of the fixed-point digital filter, simulate the performance of the fixed-point digital filter, and generate integer C/LabVIEW code for a specific fixed-point target.

In addition to tools that help you create conventional digital filters, the Digital Filter Design Toolkit includes tools for multirate digital filter design.

Software Requirements

To use the Digital Filter Design (DFD) VIs, you must be a properly licensed user of and have the following software installed on the host computer.

National Instruments LabVIEW 7.1, Full or Professional Development Systems

Note: If you want to properly use the LabVIEW code generated by the Digital Filter Design Toolkit on National Instruments RIO devices, you must have the National Instruments LabVIEW FPGA Module 1.1 installed with LabVIEW 7.1.

Installation Instructions

Complete the following steps to install the Digital Filter Design Toolkit.

Prior to installing, verify that your computer meets the following conditions:
- Verify that you installed a compatible version of LabVIEW.
- Verify that no earlier versions of the Digital Filter Design Toolkit, including beta releases, are installed on the computer.
- Verify that LabVIEW is not running.
Insert the LabVIEW Digital Filter Design Toolkit CD.
Run the setup.exe program.
Follow the instructions that appear on the screen.

Accessing the Help

Refer to the LabVIEW Help, accessible by selecting Help»VI, Function, & How-To Help in LabVIEW, for information about the Digital Filter Design VIs.

Refer to the LabVIEW Digital Filter Design Toolkit User Manual for information about using the Digital Filter Design Toolkit. The LabVIEW Digital Filter Design Toolkit User Manual (DFDT_User_Manual.pdf) is located in the labview\manuals directory.

Finding Examples

LabVIEW examples for the Digital Filter Design Toolkit are located in the labview\examples\Digital Filter Design folder. You can modify an example VI to fit an application, or you can copy and paste from one or more examples into a VI that you create.

You also can find example VIs using the NI Example Finder. Select Help»Find Examples to launch the NI Example Finder. You also can click the arrow on the Open button on the LabVIEW dialog box and select Examples from the shortcut menu to launch the NI Example Finder.

Use the Browse or Search page of the NI Example Finder to find an example VI. In the Browse page, the Digital Filter Design Toolkit examples are located in the Toolkits and Modules»Digital Filter Design folder.

Known Issues

The Digital Filter Design Toolkit 7.5 does not support the design of fixed-point multirate filters.
When you generate code with the DFD FXP Code Generator VI, use the SCTL-Optimized LabVIEW FPGA code option only on FPGA targets. If you run generated SCTL-Optimized LabVIEW FPGA code on LabVIEW targeted to Windows, you might encounter timing problems even if you have the LabVIEW FPGA Module installed.
The DFD Least Pth Norm Design VI can take a longer time to complete some designs because of its iterative algorithms.
The DFD Remez Design VI can take a longer time to design an FIR filter with a high order.
The Filter Analysis VIs take more time to analyze filters with high orders.
When converting the filter structure, you might find that the characteristics of the filter change because of the numerical precision. In the worst case, the filter with the new structure might be completely different from the original filter. If you encounter this situation, try using a different structure.
The Digital Filter Design Toolkit 7.5 does not allow zero-valued zeroes in the DFD Pole-Zero Placement Express VI. If you enter a zero-valued zero into the configuration dialog box of the DFD Pole-Zero Placement Express VI, the Express VI automatically forces the zero-valued zero to a non-zero-valued zero.
When you use the VIs from the Fixed-Point Tools palette, you must specify the quantization setting cluster. The cluster contains the signed? Boolean, which indicates whether the quantizer treats the input as a signed number. The default is TRUE, which takes the input of the quantizer as a signed number. The Digital Filter Design Toolkit 7.5 does not currently support the FALSE value.