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Computes the frequency response and the coherence based on the stimulus and response input signals and returns the results as magnitude, phase, and coherence.

Dialog Box Options

Block Diagram Inputs

Block Diagram Outputs

Dialog Box Options

Parameter	Description
Magnitude	Displays the magnitude of the transfer function. Use the Zoom button to zoom in and out of the display.
Phase	Displays the phase of the transfer function. Use the Zoom button to zoom in and out of the display.
Stimulus Signal:	Displays the input stimulus signal. Use the Zoom button to zoom in and out of the display.
Response Signal:	Displays the input response signal. Use the Zoom button to zoom in and out of the display.
View	Specifies whether to view Spectra or Time Signals.
Autoscale	Automatically adjusts the scales of the graph to display the data.
Configuration	Specifies processing parameters to apply to the frequency response measurement. Window—Specifies the window to apply to the two input signals. Choose from one of the following window options: None Hanning Hamming Blackman-Harris Exact Blackman Blackman Flat Top 4 Term B-Harris (Four Term Blackman-Harris) 7 Term B-Harris (Seven Term Blackman-Harris) Low Sidelobe Force - Exp (Force - Exponential) Force (%)—Specifies the length of the force window that the step uses if you set Window to Force-Exp. Force specifies the duration of the force window as a percentage of the total duration of the signal. Setting Force at 100 has the effect of not applying a window on the stimulus signal. Exp (%)—Specifies the decay rate of the exponential window that the step uses if Window is set to Force-Exp. Exp specifies the remaining level of the applied exponential window at the end of the signal as a percentage. Magnitude scale—Specifies if zoom power is in linear units or in decibels. The default is decibels. Unit—Specifies if the step displays the phase result in degrees or radians. Ignore timestamp—Specifies if the step includes the timestamp delay between the response and stimulus input signals in the Phase result calculation. When ignore timestamp is TRUE, the step assumes that the stimulus and response signals were sampled simultaneously. Unwrap phase—Specifies if the step unwraps the phase of the output signal. By default, the step wraps the phase between –180 degrees and 180 degrees, or between –pi and pi. Unwrapping the phase removes discontinuities greater than 180 degrees from the phase spectrum and removes the restriction that the phase must be between –180 degrees and 180 degrees. Export coherence—Specifies if the step exports the coherence result signal by creating an output on the connector of the step on the block diagram.
Averaging	Specifies the averaging parameters of the step. Averaging mode—Specifies the averaging mode from the following options: No Averaging Vector Averaging RMS Averaging Weighting mode—Specifies either Exponential or Linear weighting. Exponential averaging applies more weight to the most recent data, and linear averaging applies equal weighting to all the data. Number of averages—Specifies the number of averages used by the selected Weighting mode. Auto-restart—Specifies if the averaging process automatically restarts once the step reaches the Number of averages value. When you set Weighting mode to linear, use the Auto-restart control to configure averaging to automatically restart when Averages completed equals the Number of averages. Averages completed—Displays the number of averages completed. Averaging done—Indicates when the number of Averages completed equals or exceeds the Number of averages. Averaging done is always TRUE if the selected Averaging mode is No averaging.

Block Diagram Inputs

Parameter	Description
stimulus signal X	The stimulus signal for the frequency response measurement.
response signal Y	The response signal for the frequency response measurement.
error in (no error)	Describes error conditions that occur before this VI or function runs.
restart averaging	Specifies whether to restart the selected averaging process. The default is FALSE. When you call this Express VI for the first time, the averaging process restarts automatically.

Block Diagram Outputs

Parameter	Description
magnitude (Y/X)	Returns the magnitude of the frequency response.
phase (Y/X)	Returns the phase of the frequency response.
phase unit label	Returns the unit label for the selected phase units.
averages completed	Returns the number of averages completed by the Express VI.
averaging done	Returns TRUE when the number of averages completed equals or exceeds the number of averages specified in averaging parameters. Otherwise, averaging done returns FALSE. averaging done is always TRUE if the selected averaging mode is No averaging.
coherence	Returns the coherence of the frequency response.
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.
magnitude unit label	Returns the unit label for the selected magnitude units.