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82
Chapter 18
Technical specifications
83
Norsonic Nor118
User Guide
Microphone input socket
Pin Function
1
Heater supply (Ref pin no 7)
2
GND – signal reference
3
Polarisation voltage – selectable: 0±1 V, 200±2 V
short-circuit current <1mA, impedance: 2 M
Ω
4
Signal input
5
+15±0.5 V preamplifier supply voltage, max 3 mA
(Connected to pin 6)
6
+15 V, (Connected to pin 5)
7
-15±0.5 volt, preamp. supply voltage, max 3 mA
Housing is GND instrument casing.
Highpass filter
e input section is equipped with a highpass filter to
reduce noise from wind or other sources with frequencies
below the frequency range for measurements.
Filter type:
3rd order HP filter (-3 dB at 4 Hz, Butter-
worth response)
Analogue to digital conversion
e analogue input signal is converted to a digital signal
by a multirange sigma-delta converter with an effective
sampling frequency of 48 kHz. e anti-aliasing filter is
a combination of an analogue and a digital filter.
Frequency weightings
Simultaneous measurement of - and -weighting or -
and -weighting. ⁄ octave band or 1⁄3 octave band levels
may be measured simultaneously if options providing these
weightings are installed.
Filters:
⁄ octave filters:
8, 16, ....16000 Hz, class 1,
digital filters, base 10 system. ( ).
1⁄3 octave
filters:
6.3, 8, 10, ... 20000 Hz, class 1, digital filters,
base 10 system ( ).
Level detector
Detector type:
Digital true root-mean-square ()
detection and peak detection, resolution 0.1 dB which
may optionally be increased to 0.01 dB for indicated
levels in the range –9.99 to 99.99 dB.
frequency [Hz]
Le
vel [dB]
Highpass filter frequency response
p2
p3
p7
p5
p6
p1
p4
Summary of Contents for nor118
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