Norsonic NOR150, Instruction Manual

Page: 190 / 216

174 Chapter 24
Technical specifications
Level detector
The instrument has only one measurement range.
Reference level (unless otherwise noted) is 114 dB
sound pressure level.
Reference range is the same as the only available
measurement range.
Detector type
Digital true root-mean-square (RMS) detection and
peak detection, displayed resolution 0.1, 0.01 and
0.001 dB selectable in the instrument set up menu.
There is only one measurement range.
Crest factor capability
The crest factor is only limited by the capability to
measure the peak-value of the signal. The sound input
can measure more than 10 V peak.
Overload indication
An Overload condition is indicated in two different
ways. Both with a red light in the Status LED above
the display and with an overload sign in the status bar
in the display. Overload occurs if the input signal is
above 10 V peak (either polarity relative to ground).
Under-range indication
Each individual microphone transducer connected to
the Nor150 can have its own low level information. In
the transducer set up menu the operator can key in
the lowest acceptable level information for each 1/3rd
octave filter band and the three weighting networks.
Low level indication is only available in the SLM picture
and its corresponding numerical table. When a level
is detected that is lower than the set threshold, the
numerical value will be indicated with a “<” sign in
front of it.
Selectable range for Low Level Indication:
The selectable range of low level values goes from
-30 dB to + 40 dB in full dB steps.
A separate menu in Transducer set up gives access
to the values. The values can be altered after the
transducer is selected.
This indication is stored as a part of the measurement
data. When a new measurement is started, the under-
range indication is cleared.
Time weightings and measured functions
The time weighting functions F and S have time
constants of 125 ms and 1000 mS respectively, and
are designed as described in IEC 61672.
The time weighting I has a 35 mS on-time with a peak
hold function and a 2.9 dB/S decay rate as described
in DIN 45657 (2013).
• Simultaneous measurement of the following
functions: F–time-weighted sound pressure level,
instantaneous
• Maximum F–time-weighted sound pressure level
• Minimum F–time-weighted sound pressure level
• S–time-weighted sound pressure level, instantaneous
• Maximum S–time-weighted sound pressure level
• Minimum S–time-weighted sound pressure level
• I–time-weighted sound pressure level, instantaneous
• Maximum I–time-weighted sound pressure level