DFD Nyquist Design VI

Digital Filter Design VIs and Functions

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Owning Palette: Multirate Filter Design VIs

Installed With: Digital Filter Design Toolkit

Creates a Nyquist filter using the window or equi-ripple methods with an automatic order estimation.

You can use the Nyquist filter as a single-rate filter, an interpolation filter, or a decimation filter.

Example

Place on the block diagram

Find on the Functions palette

method specifies the method this VI uses to create the filter.

0	Kaiser Window
1	Dolph-Chebyshev Window
2	Equi-Ripple
3	Positive Equi-Ripple (default)

factor specifies the sampling frequency conversion factor of the multirate filter. The default is 4. The passband of the filter depends on factor by Nyquist sampling theorem.

order specifies the filter order. The value of order must be an even integer that is greater than zero. The default is –1. If order is not greater than zero, this VI uses the stopband attenuation input to estimate filter order. If order is an odd number, this VI returns an error.

roll off determines the relative transition bandwidth, which equals (transition band)/(2*passband + transition band). The default is 0.2. roll off must be in the range of (0,1). If the value of factor is fixed, a smaller roll off value results in a narrower transition bandwidth.

stopband attenuation specifies the stopband attenuation in decibels. The value must be greater than zero. The default is 40. If order is greater than zero, this VI ignores stopband attenuation and uses order to create the filter.

error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.

	status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
	code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
	source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

filtering mode specifies the processing mode of the filter that this VI creates.

0	No Rate Change—Does not change the sampling frequency of a signal.
1	Interpolation—Increases the sampling frequency of a signal to a higher sampling frequency that differs from the original frequency by an integer value. Interpolation also is known as up-sampling.
2	Decimation (default)—Reduces the sampling frequency of a signal to a lower sampling frequency that differs from the original frequency by an integer value. Decimation also is known as down-sampling.

multirate filter out returns a new multirate filter.

order out returns the actual order of the new filter.

error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.

	status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
	code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
	source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

Example

Refer to the Nyquist Filter VI in the labview\examples\Digital Filter Design\Floating-Point Filters\Multirate directory for an example of using the DFD Nyquist Design VI.

Open example Browse related examples

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