Frequency Response Function (Real-Im) N-1 VI
- Updated2024-07-30
- 6 minute(s) read
Frequency Response Function (Real-Im) N-1 VI
Computes the frequency response and the coherence based on the input signals. Results are returned as real part, imaginary part, and coherence.
Inputs/Outputs
window parameter specifies the beta parameter for a Kaiser window, the standard deviation for a Gaussian window, and the ratio, s, of the main lobe to the side lobe for a Dolph-Chebyshev window. If window is any other window, this VI ignores this input. The default value of window parameter is NaN, which sets beta to 0 for a Kaiser window, the standard deviation to 0.2 for a Gaussian window, and s to 60 for a Dolph-Chebyshev window. restart averaging specifies whether the VI restarts the selected averaging process. If restart averaging is TRUE, the VI restarts the selected averaging process. If restart averaging is FALSE, the VI does not restart the selected averaging process. The default is FALSE. When you call this VI for the first time, the averaging process restarts automatically. A typical case when you should restart averaging is when a major input change occurs in the middle of the averaging process. time signals X is the array of time waveforms X. time signal Y is the time waveform Y. window (Hanning) is the time-domain window to apply to the time signal. The default window is Hanning.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality. averaging parameters is a cluster that defines how the averaging is computed. The specifications of the parameters include the type of averaging, the type of weighting, and the number of averages.
FRF mode specifies how to compute the frequency response function (FRF). If you know that noise, which does not propagate through the system under test, infiltrates the input or output signals, you can select the method used for computing the frequency response function (H1, H2, H3) to minimize the measurement error.
averaging done returns TRUE when averages completed is greater than or equal to 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. real parts returns an array of the real parts of the averaged frequency responses and the frequency scales.
imaginary parts returns an array of the imaginary parts of the averaged frequency responses and the frequency scales.
coherences returns an array of the coherence functions of the averaged frequency responses and the frequency scales.
averages completed returns the number of averages completed by the VI at that time. error out contains error information. This output provides standard error out functionality. |
Typically, time signal X is the stimulus, and time signal Y is the response of the system. Each time waveform corresponds to a single FFT block. You have to pass each time waveform individually to this VI.
Examples
Refer to the following example files included with LabVIEW.
- labview\examples\Signal Processing\Waveform Measurements\Nyquist Plot of a Filter.vi