DeltaOHM HD2010UC/A, Руководство по эксплуатации

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HD2010UC/A
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V4.1
S
TATISTICAL
G
RAPHS
The functioning mode with advanced statistical analyzer allows analyses on the sound pres-
sure level with FAST time constant (sampled 8 times per second) or short equivalent level (inte-
grated every 0.125s) or peak level (calculated twice per second) with any frequency weighting (only
C or Z for peak level).
The statistical analysis is done with 0.5dB classes for sound levels from 21dB to 140dB and
provides graphic display of the sound level distribution of probabilities and percentile levels. The
graphs can be enabled in Menu >> Statistical Analyzer >> Display Statistics. Disabling the displays
does not influence the programmable L1–L4 percentile level calculation.
The following figure shows the level distribution of probabilities on the 6-minute measure-
ment of the noise issued by a climatic room. During measurement an acoustic calibrator was
switched on for about 2 minutes near the microphone.
The distribution of probabilities shows the different “population” of the examined noise
clearly. From lower levels, the first peak (about 63dBA) reflects the room background noise caused
by the ventilation system. The second peak (about 65dB) concerns the cooling compressor activa-
tion. The third peak (about 69dB) is the tone issued by the calibrator.
In the following figure the cumulative distribution for the same sample above can be seen.
The cumulative distribution is built from the 100% of the levels under the measured minimum, and
subtracting the probability of each you get 0 for the levels over the measured maximum.
The percentile levels are calculated interpolating the cumulative distribution.
The statistical analyzer resets the classes at the beginning of measurement and it will continue
accumulating the statistic until the end of the measurement. When the continuous recording is acti-
vated with the single integration mode, the integration time acts like a timer for data acquisition,
stopping automatically the measurement when the time is elapsed. When the level integration is