Norsonic nor1256, Instruction Manual

Page: 7 / 16

3 Nor1256
Instruction Manual
• Press
Hz
to select a new frequency. Press
dB
to
select a different levels.
• Press the °C/°F to display the environmental
conditions: air pressure, temperature and humidity.
The temperature and humidity is measured in-
side the calibrator. Note that due to the power
consumption of the calibrator the temperature
may rise above the ambient condition after long-
er time of operation affecting both the tempera-
ture and the humidity indication (Typically 3
°C
after 30 minutes) . It is therefore a good practice
to measure the conditions shortly after powering
the unit. The temperature may be displayed in
centigrade (Celsius) or in degree Fahrenheit.
• Press the °C/°F again for returning to the sound
calibrator mode.
• Press ON/OFF for switching the calibrator off.
The calibrator shuts off by itself after ten minutes.
However, if a microphone has not been inserted or the
level has not otherwise reached stability, the unit will
switch off after 20 seconds. The automatic power off,
may be deactivated by keeping the power on button
depressed for more than 3 seconds when the unit is
switched on (Keep the
ON
button depressed until the
red LED turns on).
Acclimatisation
Is always a good practice to let the calibrator and the
sound measuring equipment reach the prevailing en-
vironmental conditions (mainly temperature) before
using a sound calibrator. If the sound calibrator and
the microphone to be calibrated have different temper-
atures, an unstable conditions exits and the calibration
will not be reliable.
Unit for temperature
The temperature may be displayed in either degree
Celcius (°C) or degree Fahrenheit (°F). In order to
change the unit, keep the button
°C/°F
depressed
during power on.
Sound pressure levels
The sound pressure in the coupler of the calibrator
is produced by a small loudspeaker. The level is
monitored by a reference microphone and adjusted to
obtain the specified levels at the different frequencies.
All sound level meters should display at least the
A-weighted sound pressure level. The A-weighting is a
standardized, frequency dependent weighting which
originally was developed to mimic our auditory organ
and is specified in the standards for a sound level
meter. The stated levels for calibrator Nor1256 are all
un-weighted levels for both frequencies.
Power off!
The automatic power off, may be deac-
tivated by keeping the power on button
depressed for more than 3 seconds when the unit
is switched on (until the LED lights)
.