Norsonic nor140, Instructional Manual

Page: 204 / 220

186
Chapter 29
Technical Specifi cations
Windscreen
The instrument may be used with windscreen Nor1451.
The windscreen correction has to be switched on to
obtain the stated specifi cations when the windscreen
is mounted. The nominal correction for the windscreen
correction network is shown in the fi gure above.
Activating windscreen correction
• Press
SETUP
>
1
(Instr.) >
4
(Input) >
2
(Corrections)
to gain access to the Corrections menu. Navigate
in the menu as usual and activate the correction
parameter Windscr by means of the
INC
and
DEC
keys. Do the same to deactivate. Windscreen cor-
rection activated is indicated by a “
W”
in the lower
line of the display.
High levels
As an option, the instrument may measure levels 10 dB
higher than stated as the standard range. The extend-
ed measurement range is obtained by reducing the
sensitivity of the microphone through the application
of a lower polarisation voltage. When this option is se-
lected, the polarisation voltage is lowered from 200 V
to about 70 V. A correction network is applied auto-
matically to compensate for the change in frequency
response of the microphone due to the lower polarisa-
tion voltage. The nominal response for the “high level
correction network” is shown in the adjacent fi gure.
Note that the needed correction will depend on the
type of microphone, and shall only be applied when
using microphone cartridge type Nor1225.
By lowering the polarisation voltage,
the level range can be extended with-
out changing the microphone cartridge
This feature shall be used in combina-
tion with the Nor1225 cartridge only.