SmartSMS User Manual Soft dB inc.
User Manual p. 56
6.5.1.2 Reference Input Sensitivity adjustment using a Sound Level Meter (SLM) connected
to the SMS
For the Sound Level Meter option, the adjustment of the sensitivity requires the use of a certified
acoustical calibrator
7
. Figure 48 shows the set-up used for the input sensitivity adjustment. Figure
49 shows the software interface.
! NOTE:
Check the Sound Level Meter documentation to see if the AC output is A-Weighted or not.
This information is critical and needs to be specified during the input sensitivity adjustment process
with the SLM Output control.
Figure 48 : Set-up used for the Input Sensitivity Adjustment procedure
Step-by-step procedure to adjust the input sensitivity:
1. Set the dynamic range of the SLM to the 30 to 100 range, or the lowest range capable of
measuring the calibration signal (94 dB).
Note: For the sensitivity adjustment, a dynamic range which will allow measurements
between 30 and 100 dB is the most appropriate dynamic range to use, since it allows
the measurement of the typical calibration level (94 dB) and the background noise level
(generally between 33 and 40 dBA) with the same range selection. If your SLM has a
limited 50 dB dynamic range, or is unable to measure the calibration level and a
background noise of 30 dBA with the same range selection, a special procedure must be
carried out. See appendix B Sound level meter with limited 50 dB dynamic range.
2. Connect the AC output of the sound level meter to the BNC connector on the front of the
SmartSMS unit.
7
An acoustical calibrator is a device that generates a specific calibrated noise. This device allows verifying if the SML
provides a precise reading.
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