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Owning Palette: Baseband FFT VIs

Requires: Sound and Vibration Measurement Suite

Computes the FFT spectrum of scaled signal [EU]. The VI returns FFT results as a complex spectrum. Wire data to the scaled signal [EU] input to determine the polymorphic instance to use or manually select the instance.

Details  

Use the pull-down menu to select an instance of this VI.

Select an instance SVFA FFT Spectrum (Complex) (1 Ch)SVFA FFT Spectrum (Complex) (N Ch)

SVFA FFT Spectrum (Complex) (1 Ch)

	scaled signal [EU] specifies the scaled signal expressed in the selected engineering units. To obtain a properly scaled signal, you can use the SVL Scale Voltage to EU VI or define a virtual channel in National Instruments Measurement & Automation Explorer (MAX). t0 specifies the start time of the waveform. dt specifies the time interval in seconds between data points in the waveform. Y specifies the data values of the waveform.
	window specifies the time-domain window used. The default is 7 Term B-Harris. 0 None 1 Hanning 2 Hamming 3 Blackman-Harris 4 Exact Blackman 5 Blackman 6 Flat Top 7 4 Term B-Harris 8 7 Term B-Harris (default) 9 Low Sidelobe 10 Blackman Nuttall 11 Triangle 12 Bartlett-Hanning 13 Bohman 14 Parzen 15 Welch 16 Kaiser 17 Dolph-Chebyshev 18 Gaussian
	error in (no error) describes error conditions that occur before this node runs. This input provides standard error in functionality.
	averaging parameters specifies how the VI computes the averaging. The specifications of the parameters include the type of averaging, the type of weighting, and the number of averages. Note  When you set averaging mode to No averaging, the VI ignores the weighting mode, number of averages, and linear mode settings. averaging mode specifies the averaging mode. 0 No averaging (default) 1 Vector averaging 2 RMS averaging 3 Peak hold weighting mode specifies the weighting mode. The default is exponential. Note  RMS and vector averaging support linear weighting and exponential weighting. 0 Linear 1 Exponential (default) number of averages specifies the number of averages used by the selected weighting mode. The default is 10. If weighting mode is set to Linear, the measurement stops or automatically restarts after the value of number of averages has been reached. Whether the measurement stops or automatically restarts depends on the linear mode setting. linear mode specifies the behavior of the averaging if you set the value of the weighting mode parameter to Linear. If you set weighting mode to Exponential, linear mode is ignored. 0 One shot—(default) Specifies that the averaging process stops once the value of number of averages is reached. 1 Auto restart—Specifies that the averaging process automatically restarts after the value of number of averages is reached.
	restart averaging specifies if the selected averaging process has to be restarted. The default is FALSE. When you call this VI for the first time, the averaging process restarts automatically.
	complex spectrum returns the complex form of the FFT spectrum. f0 returns the start frequency, in hertz, of the spectrum. df returns the frequency resolution, in hertz, of the spectrum. complex spectrum returns the complex form of the computed spectrum.
	error out contains error information. This output provides standard error out functionality.
	averages completed returns the number of averages completed by the VI at that time.
	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.

SVFA FFT Spectrum (Complex) (N Ch)

	scaled signals [EU] specifies the scaled signals expressed in the selected engineering units. To obtain a properly scaled signal, you can use the SVL Scale Voltage to EU VI or define virtual channels in National Instruments Measurement & Automation Explorer (MAX). t0 specifies the start time of the waveform. dt specifies the time interval in seconds between data points in the waveform. Y specifies the data values of the waveform.
	window specifies the time-domain window used. The default is 7 Term B-Harris. 0 None 1 Hanning 2 Hamming 3 Blackman-Harris 4 Exact Blackman 5 Blackman 6 Flat Top 7 4 Term B-Harris 8 7 Term B-Harris (default) 9 Low Sidelobe 10 Blackman Nuttall 11 Triangle 12 Bartlett-Hanning 13 Bohman 14 Parzen 15 Welch 16 Kaiser 17 Dolph-Chebyshev 18 Gaussian
	error in (no error) describes error conditions that occur before this node runs. This input provides standard error in functionality.
	averaging parameters specifies how the VI computes the averaging. The specifications of the parameters include the type of averaging, the type of weighting, and the number of averages. Note  When you set averaging mode to No averaging, the VI ignores the weighting mode, number of averages, and linear mode settings. averaging mode specifies the averaging mode. 0 No averaging (default) 1 Vector averaging 2 RMS averaging 3 Peak hold weighting mode specifies the weighting mode. The default is exponential. Note  RMS and vector averaging support linear weighting and exponential weighting. 0 Linear 1 Exponential (default) number of averages specifies the number of averages used by the selected weighting mode. The default is 10. If weighting mode is set to Linear, the measurement stops or automatically restarts after the value of number of averages has been reached. Whether the measurement stops or automatically restarts depends on the linear mode setting. linear mode specifies the behavior of the averaging if you set the value of the weighting mode parameter to Linear. If you set weighting mode to Exponential, linear mode is ignored. 0 One shot—(default) Specifies that the averaging process stops once the value of number of averages is reached. 1 Auto restart—Specifies that the averaging process automatically restarts after the value of number of averages is reached.
	restart averaging specifies if the selected averaging process has to be restarted. The default is FALSE. When you call this VI for the first time, the averaging process restarts automatically.
	complex spectra returns the complex form of the FFT spectra. f0 returns the start frequency, in hertz, of the spectrum. df returns the frequency resolution, in hertz, of the spectrum. complex spectrum returns the complex form of the computed spectrum.
	error out contains error information. This output provides standard error out functionality.
	averages completed returns the number of averages completed by the VI at that time.
	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.

SVFA FFT Spectrum (Complex) Details

Wire the complex spectrum output of this VI to the audio measurements of the Single Tone Measurements VIs and the Distortion VIs to avoid duplicate processing. You also can use the SVFA FFT Spectrum (Complex) VI to apply any supported time-domain window before computing the complex spectrum. By default, the Single Tone Measurements VIs and the Distortion VIs use a 7-term Blackman-Harris window.