The
Pole-Zero Placement Option allows
you to interactively place and move poles and zeros on the z-plane. To do so, you can enter complex value coordinates to specifyexact values or click on a graph of the complex half plane to move
or place them with the mouse. The magnitude response of theresulting filter updates immediately as you place or move poles /
zeros.
Digital filter design utility
The Pole-Zero Placement Filter Design Interface
Zeroes
Real: Specifies the real part value if coordinates are
rectangular, or the radius value if coordinates are polar.
Imag: Specifies the imaginary part value if coordinates are
rectangular, or the angle value if coordinates are polar.
Is Real?: Makes the specified pole or zero point real if you
place a checkmark in the checkbox.
Is Linear Phase Pair?: Makes the specified pole or zero a
linear phase pair if you place a checkmark in the checkbox.
On Unit Circle?: Places the pole or zero point on the unit
circle if you place a checkmark in the checkbox.
Order: Specifies the order of the pole or zero.
Poles
Specifies the properties for each pole in the filter.
Contains the following options:
Real: Specifies the real part value if coordinates are
rectangular, or the radius value if coordinates are polar.
Imag: Specifies the imaginary part value if coordinates are
rectangular, or the angle value if coordinates are polar.
Is Real?: Makes the specified pole or zero point real if you
place a checkmark in the checkbox.
Is Linear Phase Pair?: Makes the specified pole or zero a
linear phase pair if you place a checkmark in the checkbox.
On Unit Circle?: Places the pole or zero point on the unit
circle if you place a checkmark in the checkbox.
Order: Specifies the order of the pole or zero.
Filter settings
Gain: Sets the gain of the filter manually. You can use this
control only if you remove the checkmark from the Normalized Gaincheckbox.
Normalized Gain: Specifies whether the VI automatically
adjusts the gain of the filter. The default contains a checkmark inthe checkbox, in which the VI adjusts the gain so the maximum
response is 1.0 (0 dB). Remove the checkmark from the checkbox toadjust the gain manually with the Gain control.
fs [Hz]: Specifies the sampling frequency in hertz. The input
must contain a value greater than zero.
Coordinates: Specifies whether the VI displays poles and
zeroes in rectangular or polar coordinates. The default isrectangular coordinates.
Load Filter from File: Opens a file dialog you can use to
select a file of a filter that loads into the Express VI.
Zero: Specifies the color of the zeroes in the Z Plane plot.
The default is blue. Click the color box next to the parameter nameto select a different color.
Pole: Specifies the color of the poles in the Z Plane plot.
The default is red. Click the color box next to the parameter nameto select a different color.
Delete selected: Deletes the selected pole or zero from the
filter.
Add Zero: Adds a zero to the filter.
Add Pole: Adds a pole to the filter.
Z Plane: Plots the number and location of poles and
zeroes.
Magnitude: Plots the filter magnitude response.
Magnitude in dB: Specifies whether the VI uses decibels or a
linear scale in the magnitude plot. If a checkmark is in thecheckbox, the VI converts linear magnitude response to
decibels.
Labview resources
To simplify working in LabVIEW with the filters that you design with the interactive utility on this page, we have posted several utility VIs for LabVIEW that allow you to import and export the designs that you save or load using the "Save Filter Spec" or "Load Filter Spec" buttons from the utility.
You can download a zip file containing these utilities
here .
What is labview?
LabVIEW is a graphical programming&mathematics
environment for designing, prototyping, and deploying systems. TheInteractive Digital Filter Design Utility included on this site was
built using LabVIEW 8 and the LabVIEW Digital Filter DesignToolkit.
The
LabVIEW Digital Filter Design Toolkit is a
software add-on for LabVIEW that facilitates specification,design, analysis, and implementation of digital filters. Without
prior knowledge about programming in LabVIEW, you can use theDigital Filter Design Toolkit Express VIs to interact graphically
with filter specifications to design digital filters. For more information on the LabVIEW Digital Filter Design toolkit, view the online web event
Designing Digital Filters with NI LabVIEW and the Digital Filter Design Toolkit .
The
LabVIEW
Digital Filter Design Toolkit provides
VIs that you can use to design a digital IIR or FIR filter, analyzethe characteristics of the digital filter, change the
implementation structure of the digital filter, and process datawith the digital filter. Besides the floating point support, the LabVIEW
Digital Filter Design Toolkit provides a set of VIs that you canuse to generate a fixed point digital filter model, analyze the
characteristics of the fixed point digital filter, simulate theperformance of the fixed point digital filter, and generate
integer C or LabVIEW code for a specific fixed point target. In addition to tools that help you createconventional digital filters, the LabVIEW Digital Filter Design Toolkit
includes tools for multirate digital filter design.
