Owning Palette: Octave Analysis VIs

Requires: Sound and Vibration Toolkit

Performs a third-octave analysis on scaled signal [EU] in accordance with the IEC 61260:2014 and ANSI S1.11-2014 standards. Wire data to the scaled signal [EU] input to determine the polymorphic instance to use or manually select the instance.
Note You might need to perform third-octave analysis on signals outside of the 20 Hz–20 kHz range. For example, you might need to evaluate human exposure to whole body vibration with potential signals of interest in the 0.5 Hz–80 Hz range. To perform third-octave analysis outside the 20 Hz–20 kHz range, use the SVT Fractional-octave Analysis VI and select a bandwidth equal to 1/3 octave.

Details Example

SVT Third-octave Analysis (1 Ch)SVT Third-octave Analysis (N Ch)

SVT Third-octave Analysis (1 Ch)

reset filter specifies if the octave filters have to be reset. The default is FALSE. The filters are automatically reset the first time this VI is called.
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.
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.
frequency range specifies the low and high frequencies of the third-octave analysis.
low band specifies the center frequency of the lowest third-octave band. The values for low band range from 20 Hz to 20,000 Hz. The default is 20 Hz.
high band specifies the center frequency of the highest third-octave band. The values for high band range from 20 Hz to 20,000 Hz. The default is 20,000 Hz.
dB On specifies if results are expressed in decibels. The default is TRUE. The dB reference is specified when the scaling from voltage to engineering units is applied.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
averaging type specifies the type of averaging that is applied to the result of the 1/n octave filtering. Exponential uses specific parameters defined in exp avg settings . Equal confidence uses specific parameters defined in equal confidence level [dB] .
0Linear (default)
1Exponential
2Equal confidence
3Peak
exp avg settings specifies how the exponential averaging is performed through both mode and time constant.
mode specifies the exponential averaging mode. The Custom mode allows you to specify any time constant [ms] .
0Slow t = 1 s
1Fast (default) t = 125 ms
2Impulse t = 35 ms rising and 1.5 s falling
3Custom
time constant specifies the time constant in milliseconds used for exponential averaging if mode is set to Custom. In all other cases, this parameter is ignored. The default is 125.00 ms.
equal confidence level [dB] specifies the confidence value in decibels used if averaging type is set to Equal confidence. The default is 125.00 dB.
filter settled returns TRUE when all octave filters are settled.
octave spectrum returns the octave spectrum in band power versus nominal frequencies. You can display the results in an Octave Graph or a Multiplot Octave Graph indicator.
nominal frequencies [Hz] returns the nominal, or preferred, frequencies as opposed to the exact frequencies associated with each 1/ n octave band.
band power [dB EU] returns the power associated with each 1/ n octave band expressed in decibels rms, if dB On is TRUE and EU^2 rms if dB On is FALSE.
unit label returns the selected engineering units.
total band power [dB EU] returns the sum of the rms power contained in all the octave bands.
octave info returns octave information generated by the octave spectrum and needed by the Octave Extended Measurements VIs and the Display VIs.
Note You must wire octave info when performing extended measurements. Do not modify the octave info values. If you want to view the information, you can right-click the octave info wire and select Custom Probe»Octave Info from the shortcut menu.
error out contains error information. This output provides standard error out functionality.

SVT Third-octave Analysis (N Ch)

reset filter specifies if the octave filters have to be reset. The default is FALSE. The filters are automatically reset the first time this VI is called.
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.
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.
frequency range specifies the low and high frequencies of the third-octave analysis.
low band specifies the center frequency of the lowest third-octave band. The values for low band range from 20 Hz to 20,000 Hz. The default is 20 Hz.
high band specifies the center frequency of the highest third-octave band. The values for high band range from 20 Hz to 20,000 Hz. The default is 20,000 Hz.
dB On specifies if results are expressed in decibels. The default is TRUE. The dB reference is specified when the scaling from voltage to engineering units is applied.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
averaging type specifies the type of averaging that is applied to the result of the 1/n octave filtering. Exponential uses specific parameters defined in exp avg settings . Equal confidence uses specific parameters defined in equal confidence level [dB] .
0Linear (default)
1Exponential
2Equal confidence
3Peak
exp avg settings specifies how the exponential averaging is performed through both mode and time constant.
mode specifies the exponential averaging mode. The Custom mode allows you to specify any time constant [ms] .
0Slow t = 1 s
1Fast (default) t = 125 ms
2Impulse t = 35 ms rising and 1.5 s falling
3Custom
time constant specifies the time constant in milliseconds used for exponential averaging if mode is set to Custom. In all other cases, this parameter is ignored. The default is 125.00 ms.
equal confidence level [dB] specifies the confidence value in decibels used if averaging type is set to Equal confidence. The default is 125.00 dB.
filter settled returns TRUE when all octave filters are settled.
octave spectra returns the octave spectra in band power versus nominal frequencies. You can display the results in an Octave Graph or a Multiplot Octave Graph indicator.
nominal frequencies [Hz] returns the nominal, or preferred, frequencies as opposed to the exact frequencies associated with each 1/ n octave band.
band power returns the power associated with each 1/ n octave band expressed in decibels rms.
unit labels returns the selected engineering units for each channel.
total band powers [dB EU] returns the total band power for each channel. For each channel, total band power is the sum of the rms powers in all the octave bands.
octave info contains octave information needed by the Octave Extended Measurements VIs and the waterfall display for octave VIs.
Note You must wire octave info when performing extended measurements. Do not modify the octave info values. If you want to view the information, you can create a custom probe.
error out contains error information. This output provides standard error out functionality.

SVT Third-octave Analysis Details

The third-octave filters are designed to comply with the IEC 61260:2014 and ANSI S1.11-2014 standards. To meet these standards, the sampling frequency must be at least 2.5 times the highest exact midband frequency. Example

Refer to the Demonstration of Analysis VIs (Simulated) VI in the labview\examples\Sound and Vibration\Getting Started directory for an example of using the SVT Third-octave Analysis VI.

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