Table Of Contents

Zero Phase Filtering (G Dataflow)

Last Modified: March 15, 2017

Applies a zero phase filter to a signal.

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signal

The input signal.

This input can be a 1D array of double-precision, floating-point numbers or a 1D array of complex double-precision, floating-point numbers.

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filter

Input filter. You must specify filter in direct IIR form.

Specifying filter in Direct IIR Form

Use the Filter Design node to get cascade form IIR filter coefficients. Then use the Filter Conversion node to convert the resulting filter to direct form.

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filter structure

Structure of the filter.

Name Value Description
IIR Cascade 2nd Order 0 Uses IIR second-order filter stages.
IIR Cascade 4th Order 1 Uses IIR fourth-order filter stages.
IIR Direct 2 Uses the direct-form IIR filter.
FIR 3 Uses the FIR filter.

Default: IIR Cascade 2nd Order

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forward coefficients

Forward coefficients of the filter.

Default: 0

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reverse coefficients

Reverse coefficients of the filter.

Default: 0

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sampling frequency

The sampling frequency in Hz.

This value must be greater than zero.

Default: 0

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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filtered signal

Filtered signal.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Illustration of Zero Phase Filtering Behavior

This node filters the input signal as shown in the following illustration:

g-n is the reverted sequence of gn. H(z) is an IIR filter whose coefficients are specified by filter. You must specify filter in direct IIR form.

Using the Output Signal

With a zero phase filter, the output signal has no phase distortion. Although the zero phase filter is non-causal, it is useful in offline applications such as filtering a sound file saved on disk.

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices


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