Norsonic Nor1212 Manuale utente
Instruction Manual
Outdoor Microphone Kit
Nor1212
Im1212_1Ed1R1En
May 2004
Instruction Manual
Outdoor Microphone Kit
Nor1212
Im1212_1Ed1R1En
May 2004
Nor1212 – User Guide
Im11212_1Ed1R1En – May 2004 edition
N
orsonic is a registered trademark of Norsonic AS.
Every effort has been made to supply complete and accurate information. However, Norsonic AS assumes no
responsibility for the use of – or for the consequential damage resulting from the use of – this information and/or the
instrumentation described herein. Furthermore, Norsonic AS assumes no responsibility for any infringement of the
intellectual property rights of third parties, wherever applicable, which could result from such use.
N
orsonic AS reserves the right to amend any of the information given in this manual in order to take account of new
developments.
If you wish to communicate with us, please feel welcome.
Our address is:
N
orsonic AS, P.O. Box 24, N-3421 Lierskogen, Norway
e-mail: [email protected]
Find us on the web: www.norsonic.com
Copyright © Norsonic AS 2004
All rights reserved
Norsonic Nor1212
User Guide
1
Contents
1Introduction......................................................................................................................................... 3
2Technical description......................................................................................................................... 5
3Assembling ......................................................................................................................................... 7
3.1 Devices required............................................................................................................................................................7
3.2 Assembling the outdoor microphone unit ....................................................................................................................7
3.3 Mounting on a mast ......................................................................................................................................................8
3.4 Grounding and lightening protection...........................................................................................................................9
4Microphone Calibration ................................................................................................................... 11
5Maintenance...................................................................................................................................... 13
6Specifications ................................................................................................................................... 15
6.1 Mounting direction .....................................................................................................................................................15
6.2 Acoustic performance .................................................................................................................................................15
6.2.1 Frequency response ................................................................................................................................................15
6.2.2 Directional response ...............................................................................................................................................16
6.3 General ........................................................................................................................................................................20
6.4 Accessories and spare parts ........................................................................................................................................20
Norsonic Nor1212
User Guide
3
1 Introduction
The Outdoor microphone kit Nor1212 allows the standard measurement
microphone Nor1225 with preamplifier Nor1201 or Nor1206 to be used
as an all-weather microphone for semi-permanent applications. The
Outdoor Kit protects the microphone from rain and snow, dust and
insects.
Further, the Outdoor kit improves the measurement accuracy by reducing
the wind noise and by changing the directional response of the
microphone capsule to suit vertical mounting.
The Outdoor Kit allows the Nor1225 microphone to retain its Class 1
specifications according to IEC6051 and IEC61672-1 when the weather
protection system is in place.
The acoustic sensitivity for free-field measurement microphones, like
Nor1225, is optimised for sound reaching the microphone along the axis
of symmetry. When mounted for outdoor measurements the microphone
is normally mounted with the diaphragm pointing upwards. The
microphone response will therefore be at its best for sound from above.
Even for aircraft noise monitoring, the sound will seldom approach the
microphone just from this direction. The outdoor kit has therefore been
designed to change the directional characteristics of the microphone to
improve the accuracy in other directions. The result is a microphone with
a response almost symmetrical around the horizontal plane and with a flat
random incidence response.
The Outdoor Kit allows the microphone to be calibrated with a normal
sound calibrator without the need for extra accessories. Access to the
microphone is gained by dismounting the upper part of the kit.
The outdoor kit is made of an electrical insulating material. The
microphone body will be fully insulated from the mounting mast thereby
reducing pick-up of electrical hum and noise.
4 Introduction
For improved protection in excessive humid applications, the outdoor kit
may be combined with a microphone desiccator or the preamplifier may
be heated.
Norsonic Nor1212
User Guide
5
2 Technical description
The Outdoor Kit, Nor1212, is designed to
operate in combination with Norsonic
microphone Nor1225 and the preamplifier
Nor1201 or Nor1206.
Some other types of free-field microphones
such as the Nor1223, Nor1226 and 1227 may
also be used with minor modifications of their
frequency and directional response as specified
for Nor1225.
Note that Nor1220 microphone should not to be
used with the Outdoor Kit as its uncompensated
frequency response may not be within the
requirements for a class 1 sound level meter.
If you need to connect the microphone system
to the measuring instrument with a coaxial
cable, we recommend to use the pre-polarised
microphone Nor1227 in combination with a
suitable ICP® type of preamplifier. We
recommend Nor1207 with desiccator TA202
(You need the desiccator due to the size of
Nor1207).
The outdoor kit Nor1212 protects the normal
measurement microphone Nor1225 from rain,
dust and insects, which sometimes may creep
behind the normal microphone grid. The
construction is shown on figure 2.1.
The microphone is mounted inside a tube. The
sound enters the microphone through 12
acoustic ports placed equidistantly around the
circumference. These ports have a drip-edge to
prevent water from entering the tube. For
F
igure 2.1 The sound reaches the microphone through
the mesh and acoustic ports.
6 Technical description
further protection, the ports are covered with a water-repellent mesh. This
also prevents the microphone from dust and insects.
The tube is made of polyacetal (POM). The material is durable and has a
low thermal conductivity compared to metal. This low thermal
conductivity will have the effect of raising the temperature of the
microphone and preamplifier above the ambient temperature. This heat
gain is caused by the power consumption of the preamplifier. Even a
small temperature rise will prevent condensation of water within the
microphone during humid weather conditions.
For applications in extremely humid conductions, the preamplifier Nor
1201 or Nor1206 may be further heated by applying power to the internal
heating element. See the handbook for Nor1201 for further details.
Alternatively, a desiccator type TA202 may be placed between the
microphone and the preamplifier. The desiccator absorbs water and hence
provides dry air to the microphones back vent. The desiccator needs to be
regenerated from time to time; see section 5 for information about this
maintenance operation.
Placing the microphone inside a long rod results in the acoustic
directional response being almost symmetrical above and below the
horizontal plane through the acoustic ports. This makes the microphone
system applicable for monitoring of aircraft overhead as well as industry-
and traffic-sources on the ground.
Access to the microphone is achieved by removing the upper part which
is simply unscrewed from the main body.
The base of the main body is sealed by means of the base screw. This
base screw also contains a threaded hole for mounting the microphone
system on a mast.
F
igure 2.2 Microphone system
N
or1212
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