Owning Palette: Sound Level VIs

Requires: Sound and Vibration Toolkit

Computes the exponential averaged sound level of scaled signal [EU] of exponential mode and decimates this sound level by decimation factor . scaled signal [EU] should have a zero DC component. You can attenuate the DC component with hardware AC-coupling filters and with software high-pass filters. Wire data to the scaled signal [EU] input to determine the polymorphic instance to use or manually select the instance.

The Sound Level VIs return respective sound pressure levels in dB rms relative to the reference. By default, a sound pressure level of 20 uPa rms is used as the reference for conversion to dB. In contrast, peak and peak-to-peak sound pressure levels are referenced to 20 uPa pk.

Details

SVL Decimated Exp Avg Sound Level (1 Ch)SVL Decimated Exp Avg Sound Level (N Ch)

SVL Decimated Exp Avg Sound Level (1 Ch)

decimation factor specifies the decimating factor used for the decimation of the exponential averaged sound level. The default is โ€“1. To avoid aliasing problems, choose a decimating factor to generate a new sampling frequency in accordance with the Shannon Sampling Theorem. This means that the new time period, dt on decimated exp avg sound level [dB EU] , must not exceed half of actual time constant [ms] . Choose a decimation factor of โ€“1 to have the VI automatically compute the decimation factor. The new dt will be less than or equal to the time constant divided by 10.
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.
exponential mode specifies the exponential averaging mode. The Custom option enables you to specify any positive time constant .
0 Slow t = 1 s
1 Fast (default) t = 125 ms
2 Impulse t = 35 ms rising and 1.5 s falling
3 Custom
time constant specifies the time constant in milliseconds used for exponential averaging if exponential mode is set to Custom . In all other cases, this parameter is ignored. The default is 125.00 ms.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
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.
actual decimation factor returns the actual decimation factor, or the actual value of the ratio of the input rate to the output rate.
decimated exp avg sound level [dB EU] returns the decimated exponential averaged sound level expressed in decibels.
unit label returns the selected engineering units.
actual time constant [ms] returns the time constant actually used for the selected exponential averaging mode. Slow mode returns 1000 ms. Fast mode returns 125 ms. Impulse mode returns 35 ms.
error out contains error information. This output provides standard error out functionality.

SVL Decimated Exp Avg Sound Level (N Ch)

decimation factor specifies the decimating factor used for the decimation of the exponential averaged sound level. The default is โ€“1. To avoid aliasing problems, choose a decimating factor to generate a new sampling frequency in accordance with the Shannon Sampling Theorem. This means that the new time period, dt on decimated exp avg sound level [dB EU] , must not exceed half of actual time constant [ms] . Choose a decimation factor of โ€“1 to have the VI automatically compute the decimation factor. The new dt will be less than or equal to the time constant divided by 10.
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.
exponential mode specifies the exponential averaging mode. The Custom option enables you to specify any positive time constant .
0 Slow t = 1 s
1 Fast (default) t = 125 ms
2 Impulse t = 35 ms rising and 1.5 s falling
3 Custom
time constant specifies the time constant in milliseconds used for exponential averaging if exponential mode is set to Custom . In all other cases, this parameter is ignored. The default is 125.00 ms.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
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.
actual decimation factor returns the actual decimation factor, or the actual value of the ratio of the input rate to the output rate.
decimated exp avg sound levels [dB EU] returns the decimated exponential averaged sound levels expressed in decibels.
unit labels returns the selected engineering units for each channel.
actual time constant [ms] returns the time constant actually used for the selected exponential averaging mode. Slow mode returns 1000 ms. Fast mode returns 125 ms. Impulse mode returns 35 ms.
error out contains error information. This output provides standard error out functionality.

SVL Decimated Exp Avg Sound Level Details

The SVL Decimated Exp Avg Sound Level VI reduces the amount of information returned. The SVL Decimated Exp Avg Sound Level VI helps save processing time and disk space when streaming results to disk.

The SVL Decimated Exp Avg Sound Level VI requires a continuous input data stream. An internal mechanism automatically restarts the filters if the input data flow is not a continuous flow.