Instruction Manual

Sound Level Meter Types 2245 – Instruction Manual Page 35 of 110
2.15 Overload and Underrange
2.15.1 Overload
Overload indicates that the input signal level exceed the capability of the sound level
meter with the current settings.
During measurement, overload is indicated with the flashing red triangle and by a
flashing red “traffic light” indicator. The indication is displayed as long as the overload
condition exists or for 1 second, whichever is the greater.
The final result of the measurement contains an indication with a magenta triangle
if there have been any overloads during the measurement.
If an overload condition exists, some of the input signal is clipped away and therefore
missing in the broadband results, which becomes too small. In the spectrum
measurements, due to the distortion of the signal, some of the missing signal is placed
in other bands.
2.15.2 Underrange
Underrange indicates that one or more of the measured quantities time-weighted
sound level, time average sound level, or sound exposure level is momentary below the
specified lower limit of the Linear Operating Range. The decision of whether there is an
underrange condition is taken and displayed every 1 second and is based on the results
for the last 1 second.
Underrange is indicated with a yellow triangle .
Underrange is only indicated on the screen during measurement. No underrange
information is saved with the final result of the measurement.
The underrange indication does not account for the influence of self-generated noise
from the microphone because the specifications for the lower limit of the Linear
Operating Range apply for measurements of electrical signals inserted into the
preamplifier through the applicable input device. This makes the underrange indication
a dubious indicator of the quality of the measurement.