90
Chapter 18
Technical specifications
91
Norsonic Nor118
User Guide
Analogue output
e analogue output is normally a reproduction of the
input signal from the microphone obtained by a digital
to analogue converter.
Max output voltage:
±10 volt.
Output impedance:
< 100 ohm. e output is short-
circuit proof to and output current is in excess of
10 mA
Gain accuracy at 1 kHz:
±0.4 dB.
Frequency response re. 1 kHz:
±1dB for 20 Hz < f < 16 kHz.
Serial I/O port
port, 9600 – 115200 baud. e port may be switched
off to reduce power consumption, which should be con-
sidered if a cable is attached to the socket.
Digital inputs
e digital input signals are 3.3 V signals. e
voltage levels must be within –0.25 V to +5.25 V to avoid
harming the instrument.
Input impedance:
10 kohm connected to the positive
supply 3.3 volt. Any open input will therefore be in the
high state.
Digital outputs
e digital output signals are 3.3 V signals.
Maximum output impedance:
100 ohm. If not rede-
fined by remote commands, DO-3 will go high when the
calibration mode is enabled.
Microphone heating
e microphone preamplifier Nor1206 contains a 225 ohm
resistor suitable for heating the microphone/preamplifier.
A floating voltage supply in the range 0–12 V may be con-
nected between pin 10 and 11. As the lines will be in direct
contact with the signal ground on the preamplifier, utmost
care has to be taken for not influencing the measurement
of low levels.
Data storage
Measured data is stored in the internal memory of the
sound level meter. e memory is of the “flash” type
retaining the information without battery supply.
Pin
Signal
Dir.
Remarks
1
DO-1
Out
Digital output
2
DO-2
Out
Digital output
3
DO-3
Out
Digital output for
calibration only
(high = calibration ON)
4
DTR
Out
RS232
5
TD
Out
RS232
6
PWR
Out
3.3 V, max 10 mA
7
GND
ref. digital lines
8
DI-1
In
Digital input
9
DI-2
In
Digital input
10
HEAT1 In
Power, mic. heating
11
HEAT0 In
Ref. for HEAT1
12
DSR
In
RS232
13
RD
In
RS232
14
GND
ref. analogue signal
15
AC-out Out
Analogue output
Housing GND
Instrument casing
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