Table Of Contents

Zero Phase Filtering (G Dataflow)

    Last Modified: January 9, 2017

    Applies a zero phase filter to a 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.



    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.


    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


    forward coefficients

    Forward coefficients of the filter.

    Default: 0


    reverse coefficients

    Reverse coefficients of the filter.

    Default: 0


    sampling frequency

    The sampling frequency in Hz.

    This value must be greater than zero.

    Default: 0


    error in

    Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

    Default: No error


    filtered signal

    Filtered signal.


    error out

    Error information. The node produces this output according to standard error behavior.

    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: Not supported

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