Instruction Manual

Sound Level Meter Types 2245 – Instruction Manual Page 64 of 110
For a white Gaussian signal and for 1/1-octave centre frequencies from 16 Hz to 63 Hz,
these time constants give a maximum relative standard deviation of approximately 1.5
dB. For 1/3-octave centre frequencies from 12.5 Hz to 160 Hz, these time constants give
a maximum relative standard deviation of approximately 2 dB.
4.12 Influence from the Operating Environment
The temperature and humidity specifications are given provided that no condensation
inside the sound level meter results from the combination.
Excessive condensation may cause permanent damage to the instrumentation.
4.12.1 Environmental Stabilisation Time
Typical stabilisation time after change in environmental conditions is 10 minutes.
When the sound level meter is moved from a warm environment with high humidity,
to a colder environment, care should be taken not to produce condensation inside the
sound level meter. If condensation is produced, much longer stabilisation periods may
be necessary.
4.12.2 Temperature
Operating Temperature Range: –10 to +50 °C (+14 to +122 °F)
Storage temperature range: –25 to +70 °C (–13 to +158 °F)
4.12.3 Humidity
Operating Humidity Range: 0% < RH < 90%, provided that there is no condensation
4.12.4 Vibration
Vibration Sensitivity (20 – 1000 Hz) for 1 ms
–2
: A-weighted max. 73 dB, Z-weighted
max. 83 dB
4.12.5 Immunity to Power Magnetic Fields
Maximum sensitivity to power line (50/60 Hz) magnetic field strength of 80 A/m:
is specified as the rise in the self-generated noise coming from the magnetic field. The
self-generated noise is stated in section 4.8.
Table 4.15 Rise in the self-generated noise coming from the magnetic field
Most Sensitive
Direction
Rise in Self-generated Noise
A-weighted
(dB)
B-weighted
(dB)
C-weighted
(dB)
Z-weighted
(dB)
1/3-octave
50 Hz
Band
(dB)
Magnetic field
perpendicular to the
display surface
Not
detectable
<4
<11
<7
<25