Norsonic nor140, Instructional Manual, Page: 198 / 220

180
Chapter 29
Technical Specifications
Measurement range:
0.3
m
V to 7 V (RMS) in one
range corresponding to –10 dB to 137 dB with a mi-
crophone sensitivity of 50 mV/Pa. The maximum peak
value ±10 V corresponds to 140 dB.
With the optional extension permitting extended
measurement range, peak values up to 150 dB may
be measured.
Microphone input socket
Pin Function
1
Microphone system check
2
GND – signal reference
3
Polarisation voltage – selectable: 0±1 V, 200±1 V
or adjustable 70 to 74V short-circuit current <1mA,
impedance: 2 M
Ω
4
Signal input. Input impedance: min 0,6 M
Ω
, max
250 pF. When IEPE is selected in the setup, a
constant current of 3 mA is suppled (25 volt
source).
5
+15±1 V preamplifier supply voltage, max 3 mA
(Connected to pin 6)
6
Connected to pin 5
7
-15±1 V, preamp. supply voltage, max 3 mA
Housing is GND instrument casing.
Highpass filter
The input section is equipped with an analogue high-
pass filter to reduce noise from wind or other sources
with frequencies below the frequency range for meas-
urements. The filter is switched on if the limited fre-
quency range is selected (+>6,3Hz). When this filter
is “Off” the lower frequency is 0.4 Hz. This setting is
in use when the optional octave or third octave filter is
set to “W” (for wide), or when the second weighting
network “Z-wide” is selected
Filter type:
3rd order HP filter (-3 dB at 3,4 Hz,
Butterworth response)
Analogue to digital conversion
The analogue input signal is converted to a digital signal
by a multirange sigma-delta converter with an effective
sampling frequency of 48 kHz. The anti-aliasing filter is
a combination of an analogue and a digital filter.
p2
p3
p7
p5
p6
p1
p4
Highpass filter frequency response
Filter “OFF”
Filter “ON”