RS Pro RS-660 Manuel D'instructions page 17

The meter will automatically recognize a 1 kHz calibration tone and enter
the calibration mode.
(
05/24/18 Version No. 00
key)
Logging Personal Noise Dosimeter / EN
Press key to confirm you wish to
calibrate, or press
calibration. It will take a few seconds to
automatically calibrate to 94.0 dB or 114.0 dB
during which time a progress bar is displayed
as shown.
Once the meter has successfully calibrated
the "CAL OK" message will appear.
The meter is ready to take a measurement
once the calibrator has been removed and
the windscreen re-fitted.
You may need to consult local regulations or
standards if the "before" and "after"
calibration values differ by more then
(typically) +/- 0.5dB e.g. section 12.2 of ISO
9612: 2009 suggest that measurement is
re-taken.
key to cancel the
15